The now "discontinued" WJ-8711A DSP HF Receiver in it's lightweight shell. In our testing against the best SDR and non-SDR sets of yesterday and today, we still feel it's one of the BEST HF receivers EVER MADE . I highly recommend the use of a Hammond RCBS1900517BK1 "Tabletop"cabinet (not shown above). It has been reported that 4 different Motorola DSP devices were used in the life of the receiver (see text). Similar HF1000 "consumer version" were made for a limited time frame at a lower price. Top IF bandwidth was restricted to 8 kHz on the HF1000's (WJ8711A's normally go up to 16 kHz). The DS1643 Time Keeping RAM used in most of these receivers (except early samples which used a button cell) are no longer available (alternative available, see text).

DISCONTINUED RECEIVER

What you read below include my own personal views.
One of the HF-1000A ,and Two of the WJ8711A's were tested for this report.

*** A Very Expensive Receiver ***

The first hurdle to overcome with any premium receiver like the WJ-8711A was the excessively high cost. We are NOT talking about a consumer product here.

** Very Light box and no proper feet included ***

The first observation that hits you about the WJ-8711A is it's weight. This is the lightest "Premium" tabletop receiver I have ever picked up , near 10 lbs. Both 8711A's tested did not have the internal speaker option, which would have added a couple of pounds.

The entire set is made of very thin sheet aluminum. It seems the top being a bit thinner than the bottom and sides. Overall we are talking about some very thin metal here. I would not set any other item on top of this receiver. Not a very robust case here.

The front panel is one very thick piece of aluminum. All is of a bear nature, no part is painted or anodized, except for the very front panel (front side only, rear is bear) which has a light gray painted surface. Watchout for the corners of this front panel. They have very sharp edges and one could very easy get injured.

Reports have indicated that the WJ-8711A's case and or front metal was of a anodized nature. If this was true, with later samples it was just painted to save costs ?

Another small observance is if you shake the set a bit, you will hear the "loose" internal mounting nuts that are set up to use speed screws for a rack shelf mounting brackets. If you don't plan on mounting the set using these 6 screws and the "jiggly" loose speed nuts bug you (as they did me), just insert six 10-32 x 5/16 pan head screws to tighten these up. Of course another way would be to just open the case and remove these 6 nuts and the little mounting clips.

Were all used in a table top configuration. I did not prefer the included hard pop-on plastic feet. For one they were not high enough for my liking and second were the hard variety so the set would slide around in use.

One would NOT be advised to use any self tapping screws (or ANY screws for that matter) into it's raw cabinet, say using older style rubber feet. In one mounting hole especially, this could easily contact and or penetrate the PC board/wiring and damage the receiver, let alone the metal filings that could enter the set using self tapping screws.

Best way around this would be to purchase a tabletop cabinet. "Hammond Mfg." makes very well made high quality "STEEL"tabletop cabinets that work great with these receivers and usually sell for around $ 200. USD. The WJ8711A operates cool enough so any excessive heat is not an issue being in a cabinet like this. These normally come with rubber feet  (may come with the rack screws as well with the latest productions ??), but you may wish to order the better optional rack screws with it (with plastic cup washers) for mounting. These cabinets are made in Canada. I found other ones that can be purchased elsewhere are NOT made of steel and lack strength and are more expensive to boot. I used the "Hammond" Cabinet Model Number (black) : RCBS1900517BK1, plus added the "Hammond" Package of 4 Mounting Screws and Cup Washers (Cup Washers are Black Plastic) : 1421A

*** 2 Inch thick "Chubby Manual" for WJ 8711A *** Later Samples Included a CD-ROM Manual as Well *** Power Supply Schematic ***

I must say this is one of the most comprehensive and well written manuals that I have ever seen. At around 2 inches thick it goes over every control, function, operation and option. The manual for the HF1000A was about 1/3 thinner.

Schematics for all circuits and options are shown with an exception for the SEU Speech Enhancement. It is missing as well as a "Real" parts list for it .

A downside is that it is hard to page through with it's old style "webbed" binding. One should be careful not to bend the pages in the plastic binding as you go through it as it could damage them in time. Also this manual lacks pictorials of the 3 main PC boards, in fact the only one that is shown is for the "PRE" option. One other major omission is ANY schematic for the Condor SP1348A power supply.
The 2003 sample also included a copy (of the same printed manual) in a CD-ROM (PDF format).

*** Excellent - Warmish Running Power Supply ***

Both the WJ-8711(A) and it's old very close cousin HF-1000(A) both use a INTERNAL switching power supply that provides voltage to all circuits. But do not confuse this supply with switching types that are used in consumer/computer or even amateur radio equipment. These are low cost and noisy supplies .

This excellent "custom" commercial supply was built by "Condor" in Mexico (model number SP1348A). It runs extremely clean with no RF hash and with only moderate heat.

We see a small surge protection device (an MOV) mounted near the power switch, but one would be advised to use a additional plug in device (non-MOV) to protect the set even more from power surges and spikes. A "zero-surge" (http://www.zerosurge.com/) or a "Brick Wall" (http://www.brickwall.com) surge protection product would be a excellent idea here. Switching supplies are more subject to surge and spike damage.

But over the years I have only heard of two folks with any power supply failure issues in these receivers (a couple of capacitor failures). Again please see near the bottom of this page for more information on this topic.

*** S-Meter Markings ***

The "Signal Meter" is only calibrated in dBm. So you have to do a bit of conversion over to standard s-units. Better yet just use my free conversion chart below. The later versions of the HF-1000 did indicate a few "S-Unit points" (along with dBm as well). It works excellent with it's "true" readings and have yet to see it pin .

WJ-8711 / HF-1000 Meter Conversion Chart (from dBm to S-Units).
(N9EWO Chart)

*** Displays and Lights ***

Green "LED" displays and indicators are used throughout, and as anyone knows in this department, as long as they are properly fed with the right voltage, LED's will easily outlast any liquid or gas type display. I find LED displays to be easier on the eyes as well.

You do not need any type of "dimmer" with this display, it is good at any light level.

We have only one light bulb to have to deal with, and that is of course behind the signal meter. This is in a socket and easy to change. Bulb number is a 86 (6 volt). It burns on the dim side so should not need replacing too often. But thank goodness for a socket here. Early samples of Ten Tec's RX-340 meter light is another story, good luck on a easy job here. One could always use one of those LED replacement bulbs, but it then looses the "warm fuzzy" feeling for me. The only bug that can happen is , the 86 bulb's tiny connection wires on the base can become dirty and it can flicker (just clean the wires off).

*** Memories and Tuning A Real Treat / Excellent 1 hz Tuning and Display ***

We have 100 memories. Some would say that this is a bit light and perhaps another 200 or so would be desirable ? I find the 100 works good for my uses. Having anymore would make it more of a chore of "going around the loop". The memories are used for hard to find channels and having too many would be bad.

Selecting , entering and scanning memories / frequencies is simply a first rate affair with this set. The separate display for memory channels are perfect to my operation. As you rotate this knob and select memory channels...you can have it activate as you rotate, or just display them in the "sub" display.

I like the tuning step arrangement. You can program any step you want. You may tune using this step, or select the digit of the display to tune (it flashes in this mode to indicate the selected digit). Excellent indeed.

We have a super fine 1 hz min. tuning step with of course a digit to show this. It is "dead on" across the entire tuning range as well. Here is an area where most consumer receivers/amateur transceivers are left in the dust. This makes manual ECSS tuning is simply a dream. There is even a external reference adjustment to keep this dead on too (see text located below on this same web page).

*** SAM (Synchronous AM) Near Excellent Overall ***

SAM (Synchronous AM) operates in double sideband. It's is still very useful, reduces fading distortion by leaps and bounds.

Only once in a awhile does the SAM loose lock (for split second) and usually this is because one is slightly a bit off of the center of the signal. Or if you are using too wide of a filter selection and adjacent channel interference creeps in (even a slight amount can do it). But overall it does hold lock very well (more times than not) and is very useful.

Ten Tec's RX-340 is a truly POOR performer with it's SAM (yes, I have run "side by side" test's with two RX-340 samples). It looses lock on a STRONG signal totally in the clear....ARF !!

*** Passband Tuning in CW mode / Excellent Notch Filter ***

We have Pass Band Tuning in the CW mode with the either the HF1000 or 8711. But there is a "sometimes" useful trick that most owners may already know about to use this in other modes. If you wish to "try" PBT for say an AM signal (quazi-manual ECSS) , select CW mode. Set BFO window (offset) to 0000, and then select the PBT mode and tune.

Does not always do the trick, but worth a try.

The adjustable "DSP" Notch is a huge winner. Extremely deep and sharp. Works in the AM, FM, USB, LSB, ISB, SAM modes.

*** Audio Recovery simply the BEST EVER ever used but more noise too / Punchy Audio ***

In my view where the WJ-8711 receiver shines is in the "Audio Recovery" area. With the right external speaker, this set just can make sense out of the spoken word on a very weak and even muffled station where as on a lesser set is in the noise . While not being a miracle set either..if you cannot make it out with this set..forget it !!!

We do hear a bit more of a harsher sound overall with this DSP set. Static, interference etc, can sound slightly painful to the ears. However this could be the reason why it does so well with audio recovery as well ?? SSB signals tend to have a bit of clipping distortion (even with the slowest AGC setting was used), but this was not detected at all with manual ECSS (brodadcast stations).

The audio amplifier from the speaker output with our 2003 sample has way above average punch and loudness. It works very well indeed. However, this may be questionable for later samples ?

Note : The "before" 2003 data sheet indicated the SPEAKER output level as up to 1 W and the JAN 2003 one gave the output of only 500 mW.

I do know for a fact that the 1.5 watt LM388 audio amplifier IC has been discontinued for a very long while now, and I'm wondering if they ran out and finally had to substitute a different "audio amp" IC in later samples ?

This is for "FYI" only ! Let me say here that I have no solid information on this and may mean nothing at all. However it does suggest that the audio is not as high now having a specification of only 500 mW for output? Folks that's 50% decrease in specification here vs the earlier data sheet.

My last sample was purchased in Jan 2003, and still has the 1.5 Watt LM388 IC.

*** No Local Antenna's / Some will detect Audio "Buzzies" / More noise as you grab the tuning knob on higher frequencies / Top Sensitivity ***

The 8711/HF1000's must have a antenna always away from the set using GOOD shielded antenna cable. It emits a nasty amount of noise that WILL be picked up by itself if not done. Even with a remote external antenna, there is sometimes a bit left above 15 MHz.

In certain situations on higher frequencies, touching the tuning knob increases this background "buzz" a bit. I have noticed this on both WJ8711A's and the single HF-1000 that I used.

Weirdly this does not seem to take away from the DX side of receiving weak signals. Unless I grab the knob on higher frequencies (above 15 MHz). This could very well be a trait of my antenna's and at different locations could be much different ??

The speaker output can emit a weird digital noise, but this is one of those subjective gremlins . To me is sounds like a hive of disturbed bees. Turning the speaker volume control down to min (speaker on and connected) shows this. When turned up in normal operation, I don't hear it at all. It does not emit from either rear line output, these are totally clean. Again many users may not be able to detect this at all, so it depends on your hearing. However, for some reason the Jan 2003 sample, has much less strength of this noise (if hardly any at all) .

A on/off switch on the back of an external speaker to totally shut off it's output when saying using headphones would be one idea. If you channel one of the "line" audio outputs to another external amplifier (don't use the speaker audio amplifier in the set), this should cure the speaker buzzies totally if it bothers you. Early versions of the HF1000 that use the rear DB15 connector and this "line output" idea still may not cure it.

Let me say once you do get whatever antenna PROPERLY made and placed , look out for awesome sensitivity and audio recovery. It really struts it's stuff once the self-generated gremlins are taken care of with a GOOD antenna ! It will blow you away !!

*** Both Audio Line Outputs Have "Hot" Levels ***

Connection for the audio line outputs are found on the rear mounted barrier strip block, shown below (as it is for many of the receiver outputs). Again earlier versions of the HF1000 will course have the dreaded DB-15 connector. In either case the line outputs are a bit too "hot" (loud), and appear distorted when connected to any consumer tape deck, audio mixer, mini disc etc. Level adjustment on the external equipment not helping the cause.

The simple cure of course is to just add a bit of external attenuation (one circuit for each if you use them both) from the line outputs. I used a 10K trimmer pot (using all 3 terminals, one end one as circuit ground, middle one input and other end output), mounted in a small metal box. And of course this control adjusted to proper level.

Eric Cottrell provides more information on this (many thanks Eric, however we found these values to cut a bit too much level in our testing, but is usable and improved over stock) :

"I made up an interface box with RCA Line Outs and 3.5mm Speaker Jack. The Line Outs on the Terminal Block are "hot" because they are close to Pro Audio levels. The 0 dBm nominal at 600 ohms in the specifications is 0.775 volts RMS. Pro Audio nominal level is +4 dBu or 1.228 volts RMS, which is about the level I actually measured. Consumer audio uses -10 dBV nominal level or 0.316 volts RMS."

"Consumer audio line inputs are designed to be driven by low impedance sources in voltage mode. Audio L Pad design guidelines specify the total resistance (R1 + R2) has to be greater that 6000 ohms for a 600 ohm line out, and R2 (resistor across the line input) has to be less than 1000 ohms for a 10k line input (typical value). I did not want to stray too far from these values to minimize the effects of the filter components. I used a 5600 ohm resistor for R1 and a 820 ohm resistor for R2. The audio sounded great using 16K bandwidth and feeding the aux input of my Bose Soundlink ."

The rear "TB1" connector as seen (left picture) on a WJ-8711A or a mid-late HF1000A . To achieve a proper audio "consumer line level" output with the WJ-8711 or HF-1000, some attenuation is required. I used a 10K trim pot (one for each output) to get the job done. Eric Cottrell found the above fixed resistor values to work properly (see text, but we found this to be a bit too much attenuation) .
(N9EWO Photo's)

*** Audio Connections - Do Not Tin the Wires !! *** In Need of TB1 ?? ***

The later versions of HF1000's and all WJ8711's use a rear mounted thirteen-terminal audio "terminal block" marked in the manual as "TB1", as shown above . The dreaded noisy DB-15 connectors were used in early versions of the HF1000's (see picture below). This is indeed a bit strange looking when compared to consumer / amateur equipment. The TB15 is a removable terminal block that allows you to pull it out to connect your wires into the holes, clamping these wires in this plug using screws. This system works fine, but I found in my testing that one should not tin the wires with solder. It will not make the proper "crunch" when the screw is tightened down on the wires. You will make MUCH better connections using un-tinned stranded wire and to be sure not to get too thick of a wire as well. I used 18 gauge for the speaker connections and thinner shielded wire for the "line out".

Who actually makes this plug / socket combo is hard information to locate. The manual states the mfg. of this thirteen-terminal audio terminal block socket on the receiver as "Precision Converter Design". After a bit of research here on the internet, it WAS called "Precision Connector Design, Inc" in Peabody,MA USA (PCD), but is now "Amphenol PCD" . The mfg. part number is ELFP13210 (DRS part number: 645518), the manual misses this PLUG part number totally.

Sorry, we have no sources for the TB1 removable terminal block anymore. You can do your own internet searches and hopefully unearth one (for those in need) ?

*** Watch that AGC ***

As indicated elsewhere, no matter how I adjust the AGC, SSB signals CAN have a bit of clipping distortion with certain signals. This gremlin was only heard once in awhile.

Switching over to the AGC threshold mode and dropping back the "manual gain" can help in this area when it happens , but again this could be another reason why we have superior audio recovery ??

*** 66 Bandwidths on WJ8711A up to 16 kHz (stock version) , HF1000 is more limited ***

Well this may mean a lesser importance to some, but one reason I did not like the HF1000A was the fact that bandwidths stopped at 8 kHz. I like the additional wider bandwidth filters that the WJ-8711A has that allows filtering up to 16 kHz. It really makes it for me here. I found myself using the wider filters more (above 8 kHz) than not. This really helps with audio recovery as well .

The WJ-8711A has 66 bandwidth selections from .056 to 16 KHz. USB and LSB modes have a range between .900 to 4 KHz and ISB from 1.8 to 3.2 kHz. All other modes have the entire 66 selectable bandwidths. The HF1000's is the same except it stops at 8 kHz for FM, AM and AMS modes.

One can cheat and use the CW mode (BFO set at + 0000) to provide wider SSB and "Manual ECSS" bandwidths right up to the maximum 16 kHz bandwidth. Not a perfect scenario mind you , but usable.

*** "PRE" Pre selector Option / RF Overload Circuit as a Bonus ***

With the HF1000A and the Jan 2003 WJ-8711A sample tested, the "PRE" preselector option was installed.

The manual states, the optional sub octave preselector will degrade sensitivity/noise figures between 1.5 to 2.5 db, depending on frequency. The test report that came with the set (tested for the actual sample) indicated the insertion loss at 1.2 db at 15 MHz and this appears to be correct. So a very slight loss with it in line and if you need every bit of sensitivity for a weak signal it can be bypassed.

Also if you have the "PRE" preselector option installed, it will give you the bonus of a "RF Input overload circuit" along with static input protection. 2 very important additional reasons to have the PRE option . The RF overload circuit will shut the RF parts of the set down if it detects an excessive RF input (1 watt). Will also display that the fact on one of the smaller LED displays when triggered.

WARNING : If the PRE option is not installed the internal preamp transistor (Q23 - BFQ19, SOT-89 surface mount , please note : is now a discontinued part) is much more susceptible to antenna "ESD" (static) and excessive RF damage !! In any event it's a good idea to totally "physically" disconnect the antenna when not in use .  I would not count using a grounded antenna switch either to terminate the connection .  

*** A Solid Proven Performer *** Doesn't Get Any Better Than This !! *** Anyone Repair These Receivers  ??

This receiver has been around in one form or another since the early 1990's and has seen many updates and improvements over the years (DSP IC changes etc). It has been tweaked to a pure DX machine that works fantastic for pulling very weak broadcast signals out of the noisy HF bands. Warts and all, we may never see another set like this one in our lifetime.

In my view, even today with the SDR sets, it's still one of the BEST DSP "stand alone" HF receiver for super weak broadcast listening and downright excellent performance overall I have EVER used. But again, this is NOT a consumer device and so priced (even used).

But as they say , all good things must come to an end and main WJ-8711A production stopped in mid-late 2010 (I seen reports that a VERY limited number were made after).

Rear view of a "earlier non-A version" HF-1000 (no preselector-option installed) .
As the red circle indicates, a DB-15 was used for external connections on early versions of the HF1000. The WJ8711's never used the DB-15 connector that I'm aware of. This was not a good thing as the digital buzzies were even more of a problem using this DB connector. This is why for the switch in later HF1000 versions to the "barrier strip"and was a night and day improvement for the "line" outputs (cleaner). This does not help the digital buzzies for the speaker output which can be another "minor" internal gremlin. Our last WJ8711A sample did not suffer from this. (N9EWO Photo Edit)

Repair of the "Internal Condor SP1348A" WJ-8711 - HF1000 Power Supply / SP1348A Schematic

Sooner or later the WJ-8711A's (or HF1000) internal "Custom Made" Condor SP1348A switching power supply will fail requiring repair (more so if used on a heavy basis). This is USUALLY due to electrolytic capacitors that become leaky or even worse.  All kinds of strange things can happen when the power supply starts to fail, including no or improper operation (including powering up slow),  shutting on and off erratically or errors being displayed. One should STOP operation immediately until repairs are done. Severe damage can happen if left on after the power supply starts to fail.

The 3 electrolytic capacitors that love to fail are C31 (10uf @ 63volts) , C7 (47 uf @ 35 volts)  and C5 (120 uf @ 400 Volts) . Best to just replace out all 13 electrolytic capacitors with ONLY high quality ones (at least 105c temperature rating) and be done with it. But we are not saying that other parts can't fail. Also check out the dirty connector possibility (text below). 

Information from the "Premium RX" List on this : When the power supply starts to fail it takes longer and longer to start. In the case of these sets here it is : C5 "120uf at 400 volt (105c)" HV capacitor that can become leaky ."Since the amount of current required to start is not available the power supply goes into hiccup mode. The voltage rails jump up and down and so do all of the devices on those rails. This is an unpredictable event similar to turning the power switch on and off every 3 seconds. Damage to the 1st LO amplifier and the 1st converter often occur. If your power supply is doing this don't wait until it damages your radio. Install new capacitors ASAP". As he also indicated, be sure and use high quality ones. Not the Chinese or eBay junk !! Manufacturers such as Nichicon or Nippon United Chemi-Con and at 105C temperature (or better) , low ESR parts that are proper size replacements. 

Anyway here is a list below of the electrolytic capacitors as taken from the schematic, plus a shopping list. However I do NOT have size specifications on what is needed (you are on you own here).

Anyone who owns a WJ HF-1000 or WJ-8711 series receiver already knows a schematic of this Condor SP1348(A) power supply is missing in the manual for these sets.

NOTE : I have NOT experienced this problem myself with any of the 3 samples I have owned / used .

Internal picture of the Condor SP1348A power supply as found in the WJ8711 and HF1000 receivers. Lower part of this picture shows the "C31" 10 uf 63 volt electrolytic capacitor (temp 105c) "close up" as coved in the above . C7 (47 uf at 35 volts electrolytic capacitor) also has a nasty habit of failing (drying out and going high ESR). "C5" is another one that is prone to failure (120uf at 400v / 105c). All devices screwed to the heatsink should also be checked to be sure all is tight. (N9EWO Photo Edit)

WJ-8711 / HF-1000 "Voltage and Current" requirements.

More on the WJ8711 - HF1000's Power Supply and Dirty Power Connectors (perhaps not a capacitor failure in all cases, this should be checked FIRST !!)

(Ben Bijmans from Holland with the HF1000 power supply issues......many thanks Ben).

I hope the headache here will be not be for reading my bad English.

First you have to know in all cases mentioned here, the HF1000 was further working normal, except for the messages.

After I got for the very first time the message "PS ERROR 1" in the most left display, I sent an email to DRS on what the meaning of it was. They told me that there may be a bad electrolytic capacitor in the power supply. So I did remember the story from the man down under who changed with good result the C31 capacitor (10uf 63v) in the PS (as shown/listed above..N9EWO).  And so I did, and after that the HF1000 was working for long time (about 9 months) properly. But then the message "PS ERROR 1" appears again.

For the second time I removed the old C31 and put a new, now a special type 10uf 100v electrolytic capacitor. And so again, after repair , the HF1000 worked good but now for shorter time , namely 2 months .

For the third time I put a new another new C31 capacitor, and again the HF1000 worked well without giving any message.

And then after about 4 weeks working well, not only "PS ERROR 1" appears , but also a new message was there, namely "LO ERROR ". I sent another email to DRS and they told me the meaning is the Lower PLL is not locking then. They advised me to make a cold start and so I did , but the problem was still there .

When I turned the receiver on the radio the first came the message "PS ERROR 1" going into "LO ERROR" and you can hear the receiver was not locking for a few seconds , but after about 10 seconds the radio locked and played well , but the message "LO ERROR" remains.

Having for the 4th time a bad capacitor was almost impossible in my thoughts. When I change the capacitor, the radio worked fine for a time. What more do I touch when I repair the capacitor ??? Well , simple: disconnecting the three connectors from the power supply to make it possible taking it out the receiver for repair.

With contact spray I cleaned the three connectors, WITHOUT doing ANYTHING further inside the supply. Without changing that capacitor again, the HF1000 worked well ! And now for one week the HF1000 doesn't give any error message anymore. I put the RX on and off after long and after short time working. I left it on for 24 hours . No matter what I do , it stays working well . So slowly my trust in the HF1000 is coming back.

I'm thinking that there probably was nothing wrong with the power supply at all ? The only thing from the very beginning on, was bad connections from the power supply to the PC boards. And when DRS was telling me there should be a bad capacitor, and give me more wisdom than I have normal about a receiver , I would have start with cleaning the connectors.

Ben Bijmans , Holland

The FIRST thing to check with any WJ-8711 / HF1000 receiver issues is with a possibility of a dirty 6 PIN "MAIN POWER" connector which is located on the DIGITAL ASSEMBLY PC board. Be sure and carefully clean the socket and the pins on the PC board. (N9EWO Photo Edit)

Are you seeing "RAM FAIL" message in the "Memory Channel" display at power up ??

If one sees "RAM FAIL" in the "Memory Channel" display at power up , this usually points to the RAM button cell in the black holder (early versions only) or the 28 pin-DIP "Timekeeping RAM" IC , Dallas (now Maxim)  DS1643 in mid to late samples, needs to be replaced. Either are located on the DSP Digital board. The "TimeKeeping RAM" contains a non-replaceable lithium battery.

In the case of the DS1643 , either the 120 ns or 100 ns version works fine and what was used in mid later production. The actual part number/name is : " Maxim DS1643-100+ " .

Manual covers the simple replacement instructions. IMPORTANT : Be sure and do a total reset right after it's replaced (again see the manual on how to do this). This is REQUIRED !!

*** USER COMMENTS FROM OTHERS ***

Dallas Lankford

For weak signal reception, the 340 often keeps up with the WJ8712P / WJ8711A / HF1000A, but never exceeds (the WJ circuits do a better job with weak circuits). Both TT and WJ weak signal improved with use of SE-3.

The Ten Tec RX-340 does a poor job compared to WJ on trans-pacific MW dxing where the AM stations are on 9khz spacing while US on 10 (which means that you often have a weak TP station just 1, 2 or 3 kHz from a strong USA station, even with phasing). The skirts on the DSP filters of the Ten Tec just don't hold up well in this situation.

 SAM on Ten Tec does not work well -- I don't use it. Instead you'll see that I use a SE-3 (and also for the WJ).

Don AC7ZG

PS: The WJ8712P's, WJ8711A's and HF-1000A's are far superior to the other premium receivers I own. Each has its own SE-3, DSP599zx, and Sony E10. 

My Icom IC-7800 does not hold a candle to the WJ8712P / WJ8711A / HF1000A for TP medium wave dxing, nor weak signal recovery on the shortwave bands.

Like the ICOM IC-756 Pro2 and 3, the IC-7800 has an attenuator in circuit below 1700kHz to prevent overload by AM stations. Guy Atkins has made some circuit changes to his Pro3 to bring it into play as a weak signal MW receiver, including removing the attenuation circuit and replacing the roofing filter with one of the 6kHz versions from the 7800. (I've not similarly butchered my IC-7800)

Don AC7ZG

PS:  I've used one of my WJ8711A's for receive (disabled during transmit) along with the IC-7800 to do some very weak signal ham radio qso’s -- the 7800 could not keep up.

I have had my WJ HF-1000A for many years and for the last few years used it with a Sherwood SE-3 synchronous detector. It has been my top receiver, and I have tried many other high-end receivers that have not been able to match it. Then - enter the RA6790/GM .

But first a few word of what "DX" means for me.

a) I am only DX-ing mediumwave, so all my experience with these receivers are based on frequencies below 1700 kHz - no exception ;-)

b) I only target overseas radio stations, primarily North America, Far East and Pacific.

It useful to know that I am located in a "quiet" location - approx 63 degrees north, 10 degrees east, with good "protection" (mountains) to the south. There are no local AM stations, and the strongest AM-signal on the S-meter would be S9+50 dB. I often go on DX-peditions to even more quiet locations. This means that receiver sensitivity is very important, maybe the most important property of the receiver.

Last fall I got a RA6790/GM "in transit" and tested it for a while. It's not the world's most user-friendly receiver, but I was impressed by the ability of the receiver to pick up signals and make them legible. I would say that it matched the HF1000A in most situations where there was little or no interference from nearby channels. This unit was equipped with the standard Racal filters. I used the receiver mostly with the SE-3.

I now have a RA6790/GM with (the hard-to-get) preamplifier + Rob Sherwood's filters and it's dedicated SE-3. This unit was in excellent condition and had been serviced by Gary Wingerd. This one works even better, and I find it as an excellent second receiver. Second because it's not very fast to work with when checking frequencies for carriers etc. like I often do when looking for DX. It's still not as good as the HF-1000A on weak signals close to European stations - this probably both due to the filters and the missing
notch.

To me the biggest disadvantage with the RA6790/GM is the missing notch. When using the SE-3 I get 1/2/3/4 kHz tones (dependent on the filter width) when I am too close to European stations. On the HF-1000A and a few other receivers I have, there is an IF-notch that actually nulls the carrier of the interfering stations. This is much more effective than the audio notch. I do of course use an audio notch on the RA6790/GM now, but I believe this could be better if I had an IF-notch (with have tried with and without on the HF-1000A and there is significant difference).

So compared with the HF-1000A I will say it's the closest I have tried so far. Regarding the RX-340 I have not worked a lot with it, but from what I have seen I am not impressed by its performance. It's very user-friendly (like the HF-1000A) but it does not fit my needs very well. I'd rather have a (or two) RA6790/GM than the RX-340.

73 de OJS
Trondheim, Norway

I have the 8712P - I use them extensively, along with 8711A and HF1000A variants, dxing MW and SW on the WCNA.  I don't have the 8712A's so cannot comment on these directly.

8712P are electrically identical with the WJ8711, but physically 2/3 the height (2U) and 1/2 the width of the WJ8711A( but just a little deeper). The price point is a big higher than a standard 8711A, but not by much. I have yet to see one on Ebay.

You might see an occasional 8712A variant on ebay as a bunch of 8712A boards were let go to the employees at reduced cost due to a QA mistake - - the boards were overcooked in the QA ovens during reliability tests - nothing major, the buyer didn't want them.  These are invariably the older rev of the board that won't permit the upgrade to the most recent 4.01.10 microcode.  (They are the older 4.1.2 and 4.1.3 microcode, and older motherboard).

Regards
Don

One of the bets tips I can pass along regarding the WJ HF-1000 (and most every receiver with an adjustable RF gain control) is to learn to use this control to optimize the recovered audio. With the 1000, you can select AGC Threshold mode (described in the manual); in this mode, the RF Gain control will set the AGC threshold when any of the AGC modes are selected. Using the RF Gain control in this mode is a real plus...by backing off the RF Gain to the point that the AGC stops pumping (especially in Synch AM mode), nearly all effects of fading and the like can be either eliminated or greatly minimized.

Due to the position in the circuit where the S Meter signal is derived (it is more an RF signal strength meter than an S-meter as most other receivers do it), the use of the RF Gain control will not be seen on the meter. On receivers where the S Meter signal is derived from the AGC line, you will see the meter reading rise when the RF Gain is reduced; when the meter has stopped fluctuating with fading (i.e., it is higher than with full RF gain but is stable), you've hit the optimum setting. Just sit back and enjoy consistent audio level.

This method of using the RF Gain control has the added benefit (usually) of reducing distortion in the recovered audio due to possible overloading of the detector.

Walt Novinger

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