N9EWO Review :
Lowe HF-250
HF Communications Receiver
(including HF-225 comments)
|
The discontinued and rare "Lowe HF-250 HF Communications Receiver" from
the mid-late 1990's.
Tested was a stock "Non Europa" version, plus a
second sample with PROPERLY slightly modified
narrower IF filters (see text and chart below). Simply one of the
best tabletop HF receivers for
audio quality and overall AGC performance EVER MADE especially with the
optional DU-250 Sync board installed.
Even tops the AOR AR7030 for audio quality in our view / testing
(with the PROPER 2 way external speaker). (N9EWO Photo)
Discontinued
Receiver
COUNTRY
OF MANUFACTURE: United Kingdom
Approx. Serial Number on the 2 test samples :
#1 : 4531xx (Manufactured in 1995) Firmware Ver 1.1
#2 : 4607xx (Manufactured in 1996) Firmware Ver 1.3
(Note : Previously tested a 1993 made HF-225 "stock" version and will
see references to this below. Serial No. : 3014x)
Options Tested:
- DU-250 Synchronous Detection Board / FM Unit (#1 and #2)
- WA-250 Whip Amplifier (#1)
- RC-250 IR Remote Control (#1 and #2, as shown in above photo)
Antennas used in testing:
- Comet (Japan) H-422 dipole (34 ft long)
- RF Systems MLB "Long Wire" (55 ft long)
Regulated Linear "Transformer
Type" 12 VDC Power Supplies tested with the HF-250 :
Sherwood Engineering HF-250 Lab Numbers and Report (PDF Format, click here)
PRO :
- One of the BEST HF / SW Receivers EVER TESTED for audio quality
including ultra LOW distortion with DU-250 in use (see con).
- Audio amplifier / radio circuits are totally hiss free and plenty of
output to drive most small efficient
hi-fi speakers.
- Single tone control that is very effective.
- Excellent sensitivity and low noise floor.
- Very Good Dynamic Range (see text).
- DU-250 Synchronous
Detector / FM Board that works well and features selectable sideband
(see con) [optional, was included with Europa version ?].
- LED Backlit (down to 100 Hz) LCD Frequency Display that is easy
to see / read (much improved over the HF-225/235 models).
- Accurate S-Meter that is nicely lit by 2 or 3 LED's depending on
production (see text).
- SIX excellent "Front End" Filters that are also housed in a metal can shield (filters totally lacking in the AR7030).
- Respectable "Dynamic Range" with even longer wire antenna's in use
(USA Midwest). [optional WA-250 whip amplifier should not be used with
external antenna's]
- Four (Five if you include the one in the DU-250) properly chosen
Bandwidth
Filters [11, 6 and 4 element Murata ceramic filters are used].
- 255 Memory Channels that store Frequency, Mode, Bandwidth Filter and
Attenuator settings.
- Memory Channels use EEPROM storage (are NOT battery backed unlike
with the HF-225 or HF-235 models).
- Bourns silky smooth "Ball Bearing" OPTICAL
encoder used for "Main
Tuning" solid metal knob (see con).
- Adequate OK stability (see con).
- 2 VFO's (see con).
- All push buttons have excellent tactile feedback [just as with
earlier Lowe sets and the AR7030].
- Very good above average AGC (see con).
- Electronic selection of mode (see con).
-
RC-250 IR Remote Control Option that also adds Direct Frequency Entry
(see con), [was included with the Europa version as stock ?].
- Single Step 20 db attenuator (is also switched from front panel).
- Extremely Clean rear mounted "Line Audio Output" Jack that is also at
the proper level.
- 24 Hour Clock that displays seconds.
- 2 Built in Timers.
- Rear AUDIO Mute
Terminals as well as a MUTE function on optional RC250 remote.
- ALL Metal robust case and knobs that also use set screws (except for
plastic around speaker / handle opening area).
- Built in RS-232 interface (9-pin) (see con).
- Low Current Consumption (as far as communications receivers go).
- One of the coolest operating communications receivers ever tested
[cold operation even after hours on].
- Has held up better in it's old age over the AOR AR7030 and in some
ways performs better (see AR7030 review here).
CON :
- Steep Price Tag (when new or
used market).
- Some will call the HF-250 a ergonomic nightmare with minimal number
of pushbuttons and controls.
- Single AGC is a bit SLOW (no faster selection offered).
- No RF Gain adjustment.
- VFO's do not store Mode or Bandwidth settings.
- No TCXO (Temperature Compensated Crystal Oscillator) Reference (TCXO
option was never offered, the HF-235 was the only Lowe set
that did).
- Quirky and painful mode selection scheme.
- Finicky VRIT (Variable Rate) 2 Speed Tuning System with tuning knob
is frustrating.
- Fast Frequency
Step Button (1 kHz) does not lock which make this feature much less
useful (a 2 handed affair to use).
- DU-250 Synchronous Detector Option while very good, is not as solid
locking as the Sony ICF-2010 (ICF-2001D). Certain weak signals or with
deep
fading do not always
fare well. MUST be tuned in center of a signal for best lock (that
range is very limited).
- RC-250 IR Remote Control uses non-standard numeric keypad layout and
lacks Volume Control adjustment.
- RC-250 IR remote sensor is located behind the S-Meter (low end) which
makes for difficult use if pointed at too low of an angle.
- RC-250 uses some off beat IR code (see
text).
- Top internal speaker is a disaster [a good 2 way EFFICIENT external
speaker is REQUIRED, see text]
- With firmware 1.1 (sample #1) receiver "locked up" frequently
requiring
to reapply power. Firmware 1.3 (sample # 2) cleared up most lockup
issues. (see text)
- S-Meter digits are near impossible to see with # 1 test sample. This
issue was fixed with later production as experienced with # 2 sample
(see text and photo).
- Tuning Knob can migrate (move) off of
last tuned position with any vibration's near the cabinet or sometimes even with
button
presses on the set (will make the knob rotate, see text).
- Uses a internal soldered in Lithium Button cell for Clock backup.
This is NOT
required for operation and in fact best to just CAREFULLY remove and
leave
it out entirely to rule out any leaking issues.
- As with ALL Lowe receivers and the AOR AR7030, the rear antenna
switch is prone to become intermittent in time (gets dirty). easily
fixed for most owners (Deoxit D5).
- RS232 computer interface is near useless as no official after-market
software
was ever released. Lowe had some DOS based software (not tested), but
is not usable with modern computers.
- SL6440 mixer IC's very prone to ESD damage [ALWAYS TOTALLY and physically
disconnect outdoor antenna's when not being used].
- Very common electrolytic capacitor failures (see text).
- Service Information Impossible to obtain (if it was ever released at
all ?)
WARNING :
The close cousin HF-225's service information is NOT valid
for the HF-250 ! The HF-250 never had a officially released service
manual.
N9EWO Review : Lowe
HF-250 Communications Receiver (Standard Version)
First a quick look at the HF-225 / Main Encoder / Memory Battery
The previous Lowe models before the HF-250 were the HF-125 (that
started it all for the John Thorpe receiver designs) and the improved
later HF-225, along with the lower cost HF-150 model later. Tested previously was a
stock version of the HF-225 and a number of general quirks come to mind
immediately, as good as the HF-225 was.
First the HF-225's "Alps" main tuning" control was not
only
very restrictive / hard to turn even when brand new (unless the encoder
bearing grease is/was removed and is NOT recommended) but it was was
only a
mechanical type of encoder. So was prone to become dirty and "skippy"
(ditto for the standard version of the AOR AR7030).
The very limited HF-225's 30 memory channels do not store mode and were
backed by a internally "soldered in " lithium battery. WARNING: By
now all of
these batteries have become dead (or are near dead) and are prone to
leaking/corrosion damage if not CAREFULLY taken care of. I say properly
taken care of as if not replaced or removed without care as it has been
said elsewhere the 5101P IC connected with memory operation is
very prone to ESD (Electro Static Discharge) damage and is not easily
repairable anymore.
"The
HF-225's 5101P RAM IC is EXTREMELY sensitive to ESD and is easily
destroyed even by a non ESD soldering iron. When removing the
discharged lithium cell great care MUST be taken to protect the chip
from ESD and transient voltages. One should NOT use other battery
systems say using 2 AA batteries in a holder. One will probably kill
the chip when fitting your battery holder or inserting the batteries
into it. The proper PCB mounted lithium cell (with solder tabs) is the
ONLY
recommended replacement for the original, nothing more exotic or
modified.".
|
I will NOT be held
responsible for any info that is listed here
ALL DONE AT YOUR OWN RISK !
|
Basic
receiver design of the HF-250 is very similar to the earlier HF-225 but
not
entirely. For example : There were improvements made in the first mixer
section as well as different values for the two heterodyne oscillator
adjustments. The HF-250 uses a different 11.520 MHz reference
oscillator frequency. Please don't ask me what the different
adjustments values
are as I do
not have them. If
you have SOLID proper HF-250
"het" values (as used in the TEST mode) please send a email so
this
important information can be added here.
WARNING
: Do NOT use the HF-225 service information for the HF-250.
The Lowe
HF-225
(with it's weak "2 Green LED" LCD Backlight) (John B. Photo)
The HF-225's LCD backlight brightness was another bug. It was just not
bright enough to easily see, more so for anyone with limited vision.
Some handy owners have modified the two
green backlight LED's to improve on this, but not everyone are
electronic
savvy.
John Thorpe the designer of the Lowe HF series sets (up to the HF-250),
was not with
Lowe when the actual release of the HF-250 came onto the market as by
then he had well moved on before to work for AOR UK and designed the
AOR AR7030. Completion of the HF-250 to a working and marketable
product was reported to be engineer Kevin Whitehead at Lowe's and
Richard Alton (Zycomm) who wrote the software (firmware).
Actually for awhile the HF-250 and AR7030 were in direct competition with
each other. The HF-250 was only manufactured for around 3~4 years from
early 1995 to 1998~9 (Europa version only from Dec 1996), so not huge
numbers for used samples in the market place. More exist in it's
standard version and fewer with the later Europa version. Either model
were a poky seller with its steep retail price tag and with the new kid
in the block AR7030 slurped up most of the sales with it's similar
pricing and added features.
As covered in the report below, the bugs above were addressed and
improved with the HF-250 over previous Lowe models. In some ways it was
actually was better over the AR7030 including holding up better with
age. See N9EWO's AOR AR7030
review here. .
| IF Filter |
Murata Filter
|
Specs. (kHz)
|
Sherwood
Test (kHz) |
X2
|
CFJ455K14
|
2.2
|
2.3
|
| X3 |
CFW455HT
|
6.0
|
8.8
|
X4
|
CFW455IT
|
4.0
|
5.6
|
X5
|
CFU455G2
|
9.0
|
10.9
|
X6
(SSB Carrier
Insertion Filter)
|
CFW455IT
|
4.0
|
5.6
|
X1
(on D-225
Sync Board)
|
CFU455F2
|
12.0
|
13.0~14.0
(est only)
|
Murata
ceramic IF bandwidth filters as used in the Lowe HF-225 Receiver
(Standard Version).
Sherwood Engineering HF-225
1994 testing. Of course the
HF-250 uses the same filter scheme, see text/review. (N9EWO Chart)
HF-250 Size /
Weight / Excellent Anodized Metal Case
The Lowe HF-250 is housed in a
very attractive and robust cabinet with
the sides, front and back being made out of anodized aluminum (top and
bottom are metal painted). All 3 front panel knobs are also aluminum
metal and make
use of set screws (no push on ones to be found on this radio). Also the
bottom cover attaches to the shell using 4 machine screws that insert
into the cabinet that are using real threaded inserted nuts. It's not
just using
threaded taps going into a suboptimal soft die cast metal that the AOR
AR7030 uses (which commonly strip out).
Tip
:
To enter the HF-250's cabinet (at your own risk of course) one removes
the 3 knob set screws (Volume-Tone-Main Tuning Knob). Then remove the 2
large "Hex" screws at each end on the FRONT panel. The front panel then
can be removed, then the interlocked piece on the top panel can also be
removed along with it's internal speaker and access to the PC boards.
Do NOT
remove the rear panel. IMPORTANT :
Bottom cover removal has just 4 screws, but be
careful as with one of our test samples there were plastic
(nylon) washers in between the cabinet and rear cover screws that can
be very easily
lost.
| Cabinet
Size and Weight Comparisons (no options) |
SIZE Inches
W X H x D (mm)
|
WEIGHT
Lbs (kg) |
LOWE HF-250
|
11.02 x 4.13 x
8.07
(280 x 105 x 205)
|
6.0
(2.8)
|
LOWE HF-125 / 225
|
10.0 x 4.0 x 8.3
(253 x 109 x 204)
|
4.2
(1.9)
|
LOWE HF-150
|
7.2 x 3.2 x 6.3
(185 x 80 x 175)
|
3.0
(1.3)
|
AOR AR7030
|
9.4 x 3.7 x 7.51
(238 x 93 x 191)
|
4.9
(2.2)
|
Buttons / Main Tuning Encoder / Lock
Function / 2 VFO's
Seven momentary push buttons populate the front panel for all of the
receivers operations. These are of the same type as used with other
Lowe receivers (and the AOR AR7030) and have a excellent tactile feel
along with have generally better reliability over tac or carbon contact
pad buttons in time. They also have dual and triple functions but this
was logically designed so not a negative here.
The Lowe HF-250 makes use of a OPTICAL "ball bearing" encoder
for the main tuning (knob). Made by Bourns, part number :
ENS1J-B28-L00256-256PPR. It is as silky smooth as it can get and most
welcomed vs. the low cost mechanical Alps tuning encoders as used in
all other Lowe receivers before the HF-250 (plus standard version of
the AOR
AR7030) that could (or do) become problematic in time.
One "bug-a-boo" with this, the knob is very sensitive to any
vibrations around the cabinet (it can move / tune off frequency). One
can almost tune it by just blowing on the knob. But
this is still far better than the low cost encoder
used on the HF-150 or 225 / 235’s. One could perhaps put a very thin
piece
of round felt (cut like a washer) behind this knob to help on this (not
tested) ? There is also a lock function that will help here as well. It
is activated by pressing and holding the FN / Memory button along with
the MHz DOWN (FN + Mhz UP button to turn it off). No indication on the
LCD that informs you if the lock is on or not (not a biggie here).
Tip :
If one experiences backlash with the main tuning knob (that is the knob
moves after you let go of it), flip the set over and remove and replace
the knob on a different spot in rotation (do this on a hard FLAT surface of course protecting the cabinet with proper padding). The main tuning knob uses a 2.0 mm hex key
wrench. NOTE : This may take a number of attempts to reduce or
eliminate this trait. It has to do with the solid metal knob being ever
so slightly unbalanced and throwing it's weight off. Check to
be sure that the knob is set out far enough so not to scrape the front
panel (but not too far out either). This is a bit of a trick to do properly (take your time).
TWO VFO are
provided and appreciated. These are a bit of a chore to make happen
using a function button (press and hold the MEMORY and FILTER button)
but works and even the Icom IC-R8600 receiver lacks TWO VFO's. Downside
is that the VFO's do NOT store mode or filter settings (a silly
oversight).
|
I will NOT be held
responsible for any info that is listed here
ALL DONE AT YOUR OWN RISK !
|
Excellent Front End Filtering
The Lowe HF-250 (as with the HF-225/235) uses "Six"
RF input tuning filters in the front end. These are also surrounded by
a "metal" shield. This proper filtering is totally lacking in the Lowe
HF-150 and even with the AOR AR-7030. No worries with any local
MW or FM broadcast signals bleeding into the HF-250 (no external
filtering devices required) !
LOWE HF-250 RF Input Tuning Filters
|
1. Below 500 kHz
2. 500 kHz to 1.7 MHz
3. 1.7 MHz to 4.2 MHz
4. 4.2 MHz to 11.0 MHz
5. 11.0 MHz to 19.0 MHz
6. 19.0 MHz to 30.0 MHz
|
Decent Dynamic Range (overload in testing with VERY STRONG LOCAL Amateur Signals)
Signal overloading was never really an issue with the HF-250. Even with
hot "nighttime" band conditions band conditions in the 49 meter band
with a decent long wire antenna we never detected it being swamped with
broadcast listening.
The ONLY "Dynamic Range" issue was with very local and super strong amateur radio signals.
This overloading appeared as a whistle mixed in along with a reduction
in the desired signal than the normal mishmash mess of spurious junk
sounds.
Mind you this issue will not be deal breaker for most and is of little concern (but for the record),
Low
Current Consumption / Power Supply / Cool Operation / No TCXO used
With the HF-250's low current consumption (as far as
communications receivers go), makes for a good candidate for field
portable / battery use. As you can see in the chart below, it does
consume about 100 mA more than the HF-225, but this makes total sense
with the more advanced microprocessor operation including electronic
mode selection and brighter LCD backlight etc.
One should ONLY
use a 12
volt REGULATED DC power supply with the HF-250
(and Lowe HF-150/225 receivers). Of course avoid ALL switching type
power supplies as they
will near guarantee generated noises across the HF radio frequencies.
The Jameco
170245 12 volt
regulated linear supply
was tested with both test samples of the
HF-250's (as well as the HF-225) and have adequate current and remains
on the cooler side. Last 170245 adapters purchased (2016) were still of
a
100% linear design and super RF quiet. Keep in mind that Jameco has
been in the SNEAKY process of changing over to the use of HF NOISY
switching
REGULATORS in the "Reliapro"
AC Adapter line over the years without any indication of such a
change (first hand experience on this so you have been warned). NOTE :
Jameco still call these changes with the effected adapters linear as
they still use a power transformer. The move to switching regulators
was obliviously done to reduce production costs (can use a much smaller
regulator heatsink with less heat produced).
IMPORTANT : One
will have to be handy with a soldering iron to make a change with
the DC plug on the 170245 Jameco adapter as it takes a longer length
shaft plug to
work with the HF-250 (positive tip). Philmore
# 210L (do your own internet searches) has the exact
proper plug size and length (see chart below for required
specifications).
Also tested with a
larger
"Transformer-Linear-Regulated"
Astron RS-7A power supply. Here the rear
heat was only very mildly warm even after hours of use.
Speaking of cool operation, even for hours on end the HF-250 produces
so little heat as to say its cold and stays that way (dependent on room
temperature). It and the HF-225 are the most "cool" operating
communications receivers we have ever used PERIOD. This is great news
for
longevity as ANY generated heat in a receiver cabinet is the number one
killer of
electronics (including electrolytic capacitors).
Just as with the HF-125, HF-150 and HF-225, the HF-250's "11.520 MHz"
Reference Oscillator is not using a TCXO (Temperature
Compensated Crystal Oscillator). Mind you the HF-250 is more than
stable enough, however MAJOR room temperature swings (say Air
Conditioning in the summer months) can make for very slight reference
oscillator differences and display errors. This is usually limited to
well under 10 hz which is still decent and well within
specifications.
Tip : Be sure and read the typical electrolytic capacitor failure issue section (yellow block) at the bottom of this review !
Improved LCD / Backlighting / MODE
Selection
Lowe made major improvements with the HF-250's "negative type" LCD
display when compared to earlier models. First the display now goes
down to 100 hz accuracy. This is the only Lowe "DESIGNED"
receiver to ever offer this. Next the backlighting was made more even
and with proper brightness. With a HF-225 or HF235 one can just barley
see it. For user with less than stellar vision could be even worse to
make out the frequency and sync lock status.
Mode selection is electronic and is also stored in the memory channel
data. 6 bright separate LED's are used for mode indicators. However it
is using a dreaded carousel arrangement. To make matters even worse
takes a pushbutton of the mode button, then while the mode LED(s) are
flashing one uses the up down buttons to select the mode and finally a
another press of the mode button again to get back to normal operation.
WHEW !....this exercise is a bit less tedious after awhile, but is not
ergonomically friendly.
MODES (independent of bandwidth filtering, more on this later) :
- CW (which also includes a selectable 200 hz audio filter)
- LSB
- USB
- NFM (Narrow Band FM, with DU-250 option installed)
- AMS (Double Sideband Sync, with DU-250 option installed)
- AMS LSB Sync (with DU-250 option installed)
- AMS USB Sync (with DU-250 sync installed)
- AM Standard
Tuning Steps - Fast Button / Finicky
VRIT / Not a Good "Band Scanning" Receiver
Tuning the HF-250 with the main tuning knob can be a disconcerting
exercise. There are two speeds but are ONLY selected on how fast you
spin the knob, Rotating the knob slowly gives for a very poky 8 hz
tuning step. Give it a faster spin and kicks in a faster 1 kHz step
which is the best for band scanning.
The annoying trick here is learning on where the kick in point is
between the 2 speeds. One should adjust to the scheme with some use
(well we hope anyway) ? There is FAST pushbutton on the front panel
where you are able access the faster 1 kHz step without the fast spin
of the knob, however the button is only of a intermittent type (it
can't lock) which is pity as it makes for more difficult 2 handed
tuning.
When the Sync mode is in use (DU-250 board installed) when the knob is
rotated quickly the
Sync will automatically revert to standard AM mode for easier tuning
and will switch back to Sync when tuned on a frequency (takes
about a second). This is a very useful feature.
Other Misc. LOWE HF-250
Information
|
PROPER DC Plug Size :
2.1 mm ID x 5.5 mm OD (long length shaft)
[Philmore # 210L, 1.45 inch shaft length]
[longer length required due to rear
cabinet thickness]
|
Hex Key Cabinet Screw Sizes :
Volume and Tone Knobs : 1.5 mm
Main Tuning Knob : 2.0 mm
Front Panel : 3.0 mm
|
Rear View of the Lowe HF-250.
REGULATED 12 VDC Power input REQUIRES a long shaft 2.1mm ID x 5.5 mm OD
power plug.
Firmware 1.1 and 1.3
We do not have
available a list of improvements with firmware versions (what Lowe
called software). With test sample #1 that used 1.1 firmware, frequent
total lockups of operation was experienced. This was more of a issue
when changing modes or dealing with memory channels. The only way to
restore normal operation is to totally power down the receiver.
With the later firmware 1.3 on test sample 2, these lockup issues were
nearly eliminated. Have to say almost as one time (and only one time)
in testing "lock up" did also occur. This was lock up was while in
Memory
mode. From our gathered information there was one more firmware
standard version above 1.3 (1.4 not tested) and the lone 1.5 was for
the Europa version (not tested). The "software" version is displayed
for a second at power up.
Excellent Accurate Mechanical S-Meter
The HF-250 features a excellent real mechanical signal strength meter.
Even being on the tiny side, it is most accurate and never pinning out
in testing. Very close readings when compared to the Icom IC-R8600
digital meter (S-Unit selection). With earlier production samples the
same identical meter was used in the Lowe HF-125, HF-225 and HF-235
models. Uses 2 top mounted LED's to light it up. This was a bit
inadequate as it was dim and hard to see. Lowe made an improvement here
as the #2 test sample uses 3 LED's for the S-meter lighting. Mind you
it's still lacks a bit here for meter lighting, but is
a definite improvement.
Also changed with mid-late production were the printed S-Meter markings
that were made much larger and much easier to see (photo below).
Lowe made two changes with the S-Meter on
later samples. For early production they used
the same meter as in the HF-225 with the small printing. Later they
improved the meter
with larger numbers and also added a third LED to help light up the
area better
(originally it was just 2 LED's). (N9EWO picture edit)
RC250 IR Remote Control / 255
Non-Volatile Memory Channels
Optional (expect for Europa version) RC250 Wireless IR Remote
control was tested with both samples. It is the only way to accomplish
direct frequency entry. The keyboard layout is not numerically
friendly. Changing modes is still the same chore as done directly on
the set. There is a STDBY button which works with the timer mode but
also allows for a "defacto" on and off function. Even it there is no volume level control,
a MUTE button is found on the remote which is most useful. This is
function is not found on the front of the set. A wired MUTE connection
can be found on the rear panel.
WARNING :
MUTE is of a audio type only and does NOT disable any RF stages.
The IR "receive" sensor on the cabinet is strangely located (hidden)
BEHIND on the lower part of the S-Meter. One needs to properly point
the remote high enough otherwise it's nada. Otherwise the IR range is
more than adequate. RC-250 requires 2 AAA batteries and rechargeable
types work just fine (recommended).
IR code used was for a Nokia Satellitte receiver and is NOT covered
with any of the universal type remotes. If you wish to use a Universal
type remote it will have to be of a learning type with enough memory
(and of course a original RC250 remote). A older model Sony RM-VL600
was tested with good results. This allows for much easier direct
keyboard entry.
Tip : Audio
mute function (on remote or direct rear connections) operates
while in "VFO mode" only. If attempted in memory mode only the memory
channel number appears for a second (mute not functioning.). Ditto for
making any mode changes (you MUST switch into the VFO mode first).
255 memory channels are available and also store the MODE, FILTER,
ATTenuator settings. Most importantly these do not require a battery to
retain data (uses EEPROM). The lone lithium cell is ONLY used for clock
backup when the DC power has been disconnected from the receiver
(original batteries dead in used samples now). One can cycle through
the memory channels using the tuning knob which is a very nice touch as
well as being able to directly enter (go to) the memory channel.
|
I will NOT be held
responsible for any info that is listed here
ALL DONE AT YOUR OWN RISK !
|
Internal LM2430 (CR2430) Lithium "Clock" Battery
|
The
Lowe HF-250 uses one LM2430 (CR2430) lithium button cell (soldered in
place with vertical tabs) for clock "counting" and retaining clock
timer settings when "totally" disconnected from DC power. It is NOT required (unlike with the HF
125/225/235
models) for memory data storage. The HF-250 uses a EEPROM just like
with the HF150.
By now most of these "clock" batteries have died and are prone to
leakage and possible PC board damage. So it's not a bad idea to just
remove this now dead battery entirely and just not replace it (so not
have to worry about it ever again). One will have to set the clock and
timer setting every time the HF-250 receives DC power which is no big
deal. If one attempts to remove this battery be sure and follow ALL ESD protection procedures ! We found it was easy to just VERY CAREFULLY
clip (cut) the battery out using a GOOD pair of small "Nippy" cutters (receiver
not connected to ANY power of course). No soldering iron required. See photo below.
IMPORTANT NOTE (without
a 2430 battery installed): Every time power is applied to the receiver
via the rear jack one must clear out the erroneous clock/timer data
that appears at power up. Of course you will need to set the clock
anyway. But normally timer 1 is toggled on and both timer 1 and 2 are
loaded with weird number entries. Just clear these out (set them) and
all is well. This is NOT a malfunction of the receiver in anyway here.
See page 27 in the owners manual for clock / timer setting instructions.
|
Lowe HF-250 Internal Photo (with the
DU-250 installed). Shows the location of the LM2430 lithium "Clock" backup
battery.
It
is NOT required for Memory Retention (unlike with the HF 125/225/235
models). It is a soldered in battery. (Randy M. Photo)
|
LOWE HF-250 / HF-225
**** N9EWO Current Consumption Testing ***
|
|
Tested
Current Consumption at 12.5 Volts Meter:
Fluke 77 IV f: 7490 kHz
(volume control set at normal level)
*****
LOWE HF-250 Test *****
- AM Sync ON : 340 ma PEAK
- AM (Sync OFF) - SSB / FM : 305 ma PEAK
- CW : 320 ma PEAK
***** LOWE HF-225 Test *****
- AM Sync ON : 240 ma PEAK
- AM (Sync OFF) - SSB / FM : 215 ma PEAK
- CW : 225 ma PEAK |
Actual
current
testing between the HF-250 and the HF-225. The HF-250 using about 100
ma more current
which makes total sense with it's brighter LED display
backlighting / microprocessor mode selection
- LED indicator plus additional microprocessor functions
including
non-volatile EEPROM memory. (N9EWO
Chart)
Sensitivity / Selectivity / Excellent
Image Rejection / Built in Noise Blanker
Sensitivity is equal to any other properly operating HF receiver.
IMPORTANT :
The now very
rare SL6440 mixer IC's are very prone to ESD damage. So ALWAYS TOTALLY
and physically
disconnect
outdoor antenna's when not being used (don't count on even grounded
antenna switches). Many used HF-225 and HF-250's sold today have blown
or partially blown SL6440's due to misuse (as well as blown didoes in
the front end filter section). Please keep this in mind when shopping
for a used sample.
A built in noise blanker provided by the SL6700
integrated circuit
works brilliantly (thank goodness as it cannot be turned off). PLEASE NOTE :
ALL HF-225 / HF-235 and HF-250 schematics have this IC part shown as
the SL9700 which is WRONG !
All
IF bandwidths with it's 5 included filters are totally independent of
mode (the way it should be, see chart below). Image rejection is just
excellent. Just as with the AOR AR7030, a few bridies are noticed in a
few places, but most are covered when a decent antenna is connected. A
200 hz audio filter is available in the CW mode.
Standard
Lowe HF-250
Filter Selection
|
As
Stock
(Murata) |
Real
-6db
Bandwidth
(Sherwood
Engineering
1996 Testing)
|
#2
Sample Modified
Bandwidth
Filters
(marked bandwidth)
|
Real
Bandwidth
(sounds like) |
X2
(2.2 kHz)
|
CFJ455K14
|
2.5
kHz
|
CFJ455K14
(no change)
|
2.5
kHz
|
X3 (6 kHz)
|
CFW455HT
|
6.7
kHz
|
NTK LF-H2S
(4 kHz)
|
5.5
kHz
|
X4 (4 kHz)
|
CFW455IT
|
5.7
kHz
|
NTK
LF-H2S
(4 kHz)
|
4
kHz
|
X5 (9 kHz)
|
CFU455G2
|
10.7
kHz
|
CFU455H
(6 kHz)
|
7.5
kHz
|
X6
(4 kHz)
SSB Carrier
Injection Filter
|
CFW455IT
|
5.7
kHz
|
CFW455HT
(6 kHz)
|
N/A
|
X7
(12 kHz)
DU-250 SYNC
Filter
(bypasses X5 tail filter
when ONLY used) |
CFU455F2
|
13
~ 14 kHz
(estimate) |
LTV455G
(9 kHz)
|
11 kHz
(estimate)
(N9EWO
chart)
|
Test
sample #1 was stock (no modifications) and with firmware 1.1. Test
Sample #2 (firmware 1.3) contained narrower ceramic bandwidth
filters for X3, X4, X5, X6 and X7 that were carefully chosen and
professionally done (similar to the very limited HF-225's "Finlandia"
version ?). As you can see the modified X3 and X4 filters are
of the same value/type. But when both are selected (X4- 4 kHz) gives
for improved skirt selectivity, so be it a bit narrower bandwidth/sound
compared to only when X3 is used (5.5 kHz). A HUGE plus over the
untested
Europa version here is with filter X7 on the DU-250 Synchronous
Detector board was also SLIGHTLY narrowed which improved "sync lock"
over the #1 test sample using the 10 kHz filter selection in Sync mode.
Overall these filter changes improved DX performance in testing.
Interesting part with the "sample 2 filter" changes as listed above (from
viewing PC board soldering), these appeared to have been installed at
the time of manufacture. Lab
numbers courtesy Sherwood
Engineering.
(N9EWO chart)
WARNING :
One needs to be aware that soldering work with ANY LOWE receiver must
be done extremely carefully and with the right equipment as it's very
sensitive "plated through" PC board holes are very susceptible
to heat damage (ditto for the AOR AR7030) ! To make matters even worse the PC board hole sizes are very
tight with most components. Any work like this is best
left to a professional. Obtaining the PROPER filters is another huge
problem as all have been out of production for some time.
|
I will NOT be held
responsible for any info that is listed here
ALL DONE AT YOUR OWN RISK !
|
Superb
Audio Quality / Super LOW Audio Distortion / Proper External
Speaker a MUST / Line Out Jack
Audio quality with the two tested Lowe HF-250 samples has to be
one of the lowest HF receivers for audio distortion that has ever
been tested (portable or desktop, AM signals with the DU-250 Sync board
installed). It has a very open sound that just is extremely pleasing to
the ears including decent lower end frequency response. It's superb AGC
also contributes to the end product that irks
out of the speaker. The single AGC decay rate is on the slow side but
the single value chosen is good. We did not have a AOR AR7030 on
hand to do side by side testing here, however the HF-250 just appears
to have the edge at least by a hair. See the chart below to view
Sherwood engineering test data with audio distortion.
The single tone control is very effective to adjust the high end or low
end speaker audio. However cannot provide the really deep bass audio
response
that the ICOM IC-R8600 can give with it's excellent Bass and Treble
controls. The Lowe HF-250 is cleaner sounding with less overall
distortion.
However to archive this stellar clean audio one MUST use the proper
EXTERNAL
speaker. The top mounted internal speaker (it's opening is integrated
with a very unique carrying handle) greatly disappoints and use of a
proper external speaker is required. Our favorite classic Realistic
Minimus 77 Hi-Fi 2-way speaker speaker works extremely well (as
did the
smaller Minimus 7 model)
with the HF-250. ALL other 2 way die-cast hi-fi speakers tested were
grossly inefficient for use with extremely low power audio amplifiers.
This includes most later Optimus and RCA models also sold by RadioShack
(as tested).
Rear mounted 1/8 phone jack is provided for LINE OUTPUT. Even if not
buffered independently (small "op-amp" audio amplifier) it's extremely
clean and has proper output level.
AUDIO
DISTORTION
Sherwood
Engineering Data
|
LOWE HF-250
|
AOR AR-7030 |
Eton / Grundig E1
|
Ten Tec RX-320 / RX-321
* In Band Noise Floor - 60db
|
| AM
100 hz |
Narrow
Bandwidth : 1%
Wide Bandwidth : 1%
|
5
kHz Bandwidth : 3%
|
4%
|
1%
|
AM
200 hz
|
Narrow
Bandwidth : 1%
Wide Bandwidth : 0.7%
|
5
kHz Bandwidth : 2%
|
2%
|
1% |
AM
400 hz
|
Narrow
Bandwidth : 1%
Wide Bandwidth : 0.5%
|
5
kHz Bandwidth : 1%
|
2%
|
.8% |
AM
1000 hz
|
Narrow
Bandwidth : 2%
Wide Bandwidth : 1.0%
|
5
kHz Bandwidth : 1%
|
2%
|
.3% |
AM
2000 hz
|
Narrow
Bandwidth : 5%
Wide Bandwidth : 1.5%
|
5
kHz Bandwidth : 1%
|
2%
|
.1% |
AM
Sync 100 hz
|
Narrow
Bandwidth : 2%
Wide Bandwidth : 2%
|
5
kHz Bandwidth : 3%
|
3.5%
|
Not
Available |
AM
Sync 200 hz
|
Narrow
Bandwidth : 1%
Wide Bandwidth : 1%
|
5
kHz Bandwidth : 1.5%
|
1.5%
|
Not
Available |
AM
Sync 400 hz
|
Narrow
Bandwidth : 0.5%
Wide Bandwidth : 0.5%
|
5
kHz Bandwidth : 1% |
2.7%
|
Not
Available |
AM
Sync 1000 hz
|
Narrow
Bandwidth : 0.5%
Wide Bandwidth : 0.5%
|
5
kHz Bandwidth : 1%
|
2.7%
|
Not
Available |
AM
Sync 2000 hz
|
Narrow
Bandwidth : ?
Wide Bandwidth : 0.3%
|
5
kHz Bandwidth : 1%
|
2.7%
|
Not
Available |
SSB
100 hz
|
3%
|
(noise)
1%
|
1.5%
|
* < 0.3 % |
SSB
200 hz
|
1.5%
|
(noise)
1%
|
1%
|
* < 0.3% |
SSB
400 hz
|
0.3%
|
0.3%
|
0.7%
|
* < 0.1%
|
SSB
1000 hz
|
0.1%
|
0.2%
|
1.5%
|
* < 0.1% |
SSB
2000 hz
|
0.1%
|
0.1%
|
3%
|
* 0.1% |
DU-250 Synchronous Detector / FM Board
DU-250
Synchronous Detector board option is a near requirement for the HF-250.
It was a optional "soldered in" accessory board except for the later
Europa version (not tested). Unlike the D-225 Synchronous
Detector board
in the HF-225, the DU-250 has "selectable sideband" sync available
which allows for improved interference rejection. A handy green AMS
LOCK LED is provided, however even if it does not lite does not mean it
is totally out of lock.
As it is very common with HF-250's with the DU-250, one will usually
find the LSB AMS selection to sound a bit sharper vs. USB AMS. This bug
can actually be a huge advantage as can give for uncanny excellent
audio recovery on weak signals even with narrower bandwidth's in use.
One needs to have the lock point of the detector in the middle of a
carrier for proper operation. However in practice we found just
slightly RIGHT of carrier center for the best audio. It does not lock
as well as say the classic Sony ICF-2010 / 2001D Synchronous Detector as
(rarely) it can drop out slightly with very deep fading signals even on
strong signals. But overall the HF-250's "Sync" is a stellar performer.
FM mode is also included with the DU-250. This is most useful for the
10 Meter Amateur band along with the rare Shortwave pirate that decides
to try something out of the ordinary. A squelch control can be found on
the rear panel.
24 Hour Clock With Seconds / 2 Event Timer
When the HF-250 is off a 24 hour clock with seconds is displayed
(backlight is dimmed). However one can view the clock when powered ON
by pressing the FAST and MODE buttons together (NOTE : You MUST be in
VFO mode to do this). To return to the frequency display press MODE
once and WAIT a second.
2 programmable timers are featured. It does not have relay contacts for
a old school tape recorder however.
One Of BEST Sounding HF Receivers Ever
Tested (if not the best) / Have Held Up Well With Age
As far as audio quality goes,
it's extremely difficult to beat the Lowe HF-250. Mind you it has it's
share of "bug-a-boos" as well.
In our view it has held up much better in it's old age vs. the AOR
AR7030.
Properly operating and in decent condition samples are fairly rare on
the used market now (even more so in North America). Most owners know
what the receiver is and hang on to them. But once in a great while one
does show up on the used market (heed warnings of possible abused parts as covered in the text above !).
Dave N9EWO
© N9EWO, all rights reserved
Ver 3.1
Discontinued
Receiver
| Very Common LOWE Electrolytic Capacitor Failures |
Even with the HF-250's extremely cool operation, there are TWO electrolytic
capacitors on the main board that should be replaced in EVERY Lowe
HF-125, HF-225, HF-235 and HF-250 (HF-150?) receiver on the planet. This is a
very common failure trait. Voltage stressed electrolytic capacitors
C156 and 157 (both 100 uf at 10 volt rating) go bad or we should say are BAD. These should both be replaced with 100 uf ones
having a 16 volt rating. Of course this is for the electronic savvy and
be sure NOT to use too much heat and a small soldering iron tip and proper de-soldering device
(otherwise damage will happen to the board), WARNING : Uses plated
through holes. Be sure and use QUALITY replacement capacitors (nichicon etc) and some TLC.
Both
test samples suffered from these capacitor
failures. Can lead to strange wooshy-rumbling sounds in the audio to
total receiver
dropouts (including totally DEAD) and weird Sync operation. With the later sample the 8 volt
regulator capacitor vented with some electrolyte oozed out (thank goodness no
damage to the PC Board in this case, but it can happen). These are NOT surface mounted capacitors
(standard radial lead type).
With the front of the cabinet facing you C156 is located on the far
left side, just right of the 2 voltage regulators IC's. C157 in located
right in the middle of the PC board FRONT edge. It's a bit tight with the
front panel metal shield cut out area. See my provided photo with markings (click here) or the HF-225 service manual for
the detailed board location (it's in the same location and part numbers).
Another possible part failure is L46 (100 uh choke)
failure. Receiver is dead in this case (display works). Have a peek at this You Tube
video : LOWE HF-250 RESCUED AND REPAIRED! (open L46 100 uh choke)
Very common 100 uf electrolytic capacitor failures with ALL HF-250's in it's old age.
C156 and C157 as marked in RED above See text above for detailed information.
C162 marked in Blue is a optional replacement (470 uf at 16 volt) ?
Click on lower photo for closer view. Our Lowe capacitor "PDF Document" (click here)
(N9EWO photo edit)
Here
is reason why ALL owners of the LOWE HF-125, HF-225, HF-235 and HF-250
should replace C156 and C157 electrolytic capacitors NOW.
Photo of the vented and swelled BAD C156 capacitor as covered above.
Being this venting happened from the bottom one would not have noticed
it until removed (it's also located in a fairly tight spot). (N9EWO Photo)
Dave N9EWO
© N9EWO, all rights reserved
Ver 2.0
|
I will NOT be held
responsible for any info that is listed here
ALL DONE AT YOUR OWN RISK !
|
|
Sherwood Engineering HF-250 Lab Numbers and Report (PDF Format, click here)
Lowe
HF-250 links for additional Information (all subject to change without
notice)
-
Lowe HF-250 "Owners Manual"
-
Lowe HF-250 "Advanced Information" (Brochure)
- LoweHFReceivers on "groups.io"
HF-250 "You Tube" Video's
- General Lowe
HF-250 Video (Japan)
- Lowe HF-250
Filters and Tone Control
- LOWE HF-250 RESCUED AND REPAIRED! (open L46 100 uh choke)
Lowe HF-225 links for additional
Information (all subject to change without notice)
(PCD)
5101P RAM IC used on HF-225 Control Board Q204 (available USA source
and are very hard find now)
(PCD) 5101P
RAM IC used on HF-225 Control Board Q204 (second USA source)
