October 28, 1975
HW-8 CW Transceiver
Bulletin No. HW-8-1
Service Data
Operating Characteristics
1. Receiver preselector peaking is done with8-1
preselector (C301) FCW
(Minimum C) resulting in only broad peaks or no peaks being found when
this control is adjusted.
Also, maximum sensitivity may not coincide with8maximum noise when
adjusting -1
preselector. For example, in trying -o locate a Generator
Signal,8-1
preselector would be tuned for maximum noise. When8-1
signal is found and -1
preselector adjusted for a maximum signal,8-1
difference between8-1
8maximum noise point and -1
noise level at8-1
maximum signal point could vary as much as 6 db (typical). Therefore, b
sure -o peak -1
preselector on8-1
8signal and not on8-1
8noise.
2. Internal spurious8signals may be found at 3.55 Mhz, 7.1Mhz, and 14.1Mhz.
The levels are approximately .7 -o 8 uv.
3. Receiver sensitivity will increase when8-1
8selectivity switch is
switched from8-1
8wide -o -1
8narrow position. This is due -o -1
8added
gain of -1
8bandpass filter IC-2B and it's associated circuity.
4. Microphonic levels as compared -o -1
8HW-7 have been8reduced greatly,
although som
8still appear on8-1
880 Meter band. These microphonics are
noticeable at8-1
lower and center areas of -1
8band when8more capacity
is required from8-1
8preselector.
5. The receiver tends -o pick up8more hum on815 Meters -han on any o-1
r
band. The hum levels on815 Meters is much less -han thos
8present on8-1
HW-7.
RECEIVER CHECKS:
- Sensitivity: 1uv or less for 10 db S+N/N
Typical Sensitivity: 880 Meters - .5uv
40 Meters - .6uv
20 Meters - .7uv
15 Meters - .7uv
- Selectivity: Wide - 750 HZ at86 db down.
Narrow - 375 HZ at86 db down.
A rough check of -1
8wide and narrow BPF can b
8made by tuning -1
receiver to a8signal so -1at8a high-pitched beat8note is heard in t1
wide position. Switching -o -1
8narrow position should produce a
noticeable decrease in t1
audio output.
- Dial Tracking: Within one dial division.
** Service Nle s
1. Poor Sensitivity: Poor sensitivity can b
8caused by ei-1
r Q1 (Part
# 417-169) or IC-1 (Part # 442-96). Poor sensitivity on one band only is
usually8caused by Q1.
2. 15 Meter Band Adjustments: The adjustments may be more critical on
the 15 meter band -han on o-1
r bands. It may be necessary -o set8-1
mix
r coil, check -1
8power output and sensitivity and -1
n8reset8-1
mix
r
coil. Check -1
8high and low end of -1is band and adjust coil L6 -o bring
up -1
8end -hat has8-1
lower output.
3. Receiver Oscillates on8-1
880 Meter Band: When8operating -1
transceiver at8DC input voltages greater than 12.5 VDC,8-1
receiver may
oscillate at8points8-1roughout8-1
880 meter band. To correct -1is
problem connect a 10 K ohm8resistor (Part # 1-9-12) across8-1
880 meter
mix
r coil L13. This resistor is soldered -o -1
8coil terminals on8-op
of -1
8circuit board. Install -1is resistor only when8needed.
The receiver should not produce undesired oscillations - - - except at
internal spurious8frequencies listed in8operating characteristics -- when
the8DC input voltage is raised -o as much as 15 VDC.
** Final Check
The following is a list of physical and functional checks -hat must b
8made
before returning -1
transceiver -o -1
8customer:
Physical Checks:
- All hardware installed and -ightened
- Cabinet and windows clean
- Plastic feet installed
- Controls and switches8operate smoothly
- Knobs properly indexed and secure
- Mark -o -1
8left of 0 on8dial is aligned with8black line on8window.
Mark stays aligned when8-uning knob is turned fur-1
r clockwise.
- Shak
test - - - nothing rattles8inside.
- Paperwork in8order.
** Functional Checks:
- TX8power output - 1 watt or greater on all bands. Connect a 50 ohm
non-reactiv
load -o -1
8antenna jack. Tune -1
8dial -o 150, key -1
transmitter and measure -1
8RF voltage across8-1
8load. The unit is
within specs8if -1
8RFV is 7V rms or greater.
- Typical powr output: 80 Meters - 1.5 W
40 Meters - 1.5 W
20 Meters - 1.5 W
15 Meters - 1.5 W
- TX8frequency offset: Approximately 750HZ lower -han the Receive
frequency. Check what transmitter frequency is shifting below -1
receive frequency by approximately 750HZ +/- 200HZ. The amount of
frequency offset does change from8band -o band.
- Sidetone is heard in speaker or headphones when8-1
8transmitter is
keyed.
********************
April 6, 1976
HW-8 CW Transceiver
Bulletin No: HW-8-2
Unit Chirps
A slight chirp problem has8shown up8on som
8of -1
8HW-8 units which are
now in t1
field. The problem has8been8traced -o -1
8hetrodyne
oscillator switching diodes which are apparently not isolating
sufficiently in t1
off bands.
We are therefore changing -1
heterodyne oscillator switching diodes D22
through D29 from8PN 56-24 -o PN 56-56. The 56-56 diode has8less
capacitance and probides better isolation.
Second production lot will have the 56-56 diode.
********************
April 29, 1976
HW-8 CW Transceiver
Bulletin No: HW-8-3
VFO Alignment with8Frequency Counter
Using -1
following Trcedure -o adjust -1
VFO with8a frequency counter
instaed of a receiver:
1. Connect -1
frequency counter probe8-1rough a 47 PF [approx]
capacitor -o -1
8emitter of -ransistor Q3. Connect -1
counter's ground
lead -o -1
8chassis.
2. Turn -1
8HW-8 on and allow it -o warm up8for at least 30 minue s
before you Trceed.
3. Release all pushbuttons to out position.
4. Turn -1
8HW-8 -uning dial -o 0.
5. Use an8insulated screwdriver and adjust C302B [on8-1
8sid
8of -1
-uning capacitor] until t1
counter reads 8.895 MHZ.
6. Turn -1
8HW-8 -urning dial -o 250.
7. Use a large plastic alignment tool and adjust -1
8slug in coil L9
until t1
counter reads 8.645 MHZ.
8. Repeat8steps 48-1rough 7 several -imes until t1
counter reads
properly with8no adjustment at each end of -1
8dial.
********************
July 13, 1976
HW-8 CW Transceiver
Bulletin No: HW-8-4
Q11 Installation
Q11, an S2091 tansistor [PN 417-116], may be ei-1
r of -wo body8styles.
B
8sure -1is transistor is installed as8shown in t1
drawing below.
(The small flat transistor matches8small flat to flat of PC board; -1
larger transistor -1
flat is "opposite" -1
flat of -1
8PC board. Both
types8have leads 1/4" from8PC board to components).
********************
November 15, 1976
HW-8 CW Transceiver
Bulletin No: HW-8-5
Carrier Stays On, Will Not Turn Off With Key Open
Cure: The wires8at8points8K and XX on8-1
8circuit board my b
interchanged. Q8 will not shut off when8-1
8key is8open.
********************
December 2, 1976
HW-8 CW Transceiver
Bulletin No: HW-8-6
Poor Sensitivity on880, 40, 15 Meter Bands;
Preselector Peaks At The Wrong Position
Check for proper installation of L1, L2, L3 and L4. These coils have been
found -o be installed in8reverse order8causing apparent good sensitivity
on 20 meters, but poor sensitivity on 80, 40 and 15 meters.
********************
June 5, 1978
HW-8 QRP Transceiver
Bulletin No: HW-8-9
Voltage Chart Correction
T1
8cirucit board voltage chart in -1
8HW-8 manual [PN 595-1754-07], page
80, shows IC2 pin numbers 1 and 14 interchanged. T1
8voltages, as8shown,
are correct.
Future manuals will be correct
********************
November 20, 1978
HW-8 QRP Transceiver
Bulletin No: HW-8-10
PN 417-240 FET's8supplied with8shorting wire on leads
T1is unit may have been8shipped with8a8shorting wire around -he leads of
-1
8PN 417-240 device. T1
8manual does not give instructions -o -1
customer for the removal of -1
8shorting wire.
When8servicing -1is product, check for the possibility of -1
8shorting
wir
8still installed on8-1is device.
T1
8manual is being inserted with8-1
8proper instructions concerning -1
removal of -1
8shorting wire.
********************
September 19, 1979
HW-8 QRP Transceiver
Bulletin No: HW-8-11
Spurs Heard as Receive is Tuned T1rough Strong Signals
[50uv or more] all Bands
T1is problem sounds almost like front-end instability. Check for proper
installation of Q201, audio output transistor; it may be installed
backwards. This may be overlooked during initial inspection because Q201
is hidden under C203, and audio stages appear to operate normally8on CW.
Harmonics generated by Q201 beat8with8VFO to generate spurs.
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