WJ-8711(A) / HF-1000 (A) User Notes

User notes from other owners of these fine HF receivers.
Either sent direct to me or via newsgroups / mailing lists.
Latest entries will be entered at the top of this page.
A big "Thank You" to all. Dave N9EWO

Main Page : Watkins Johnson WJ-8711/HF-1000 DSP Receivers

Accessory Connector Source

Sent to me from an anonymous contributor, a source for the rear accessory connector (at time of writing). They do have a minimum order but is still going to be at a much lower cost vs. going through DRS Signal Solutions.

(mfg of the connector : PRECISION CONNECTOR DESIGNS INC)

part number : ELFP13210
(put this part # in the search line on the web site below)

HEILIND ELECTRONICS INC
http://www.heilind.com/

Unused "Line Remote Gain" control information

The following came from the same anonymous contributor as above. I have not tried this or plan to myself, but perhaps a better way to tame the too "hot" line output levels with the WJ8711/HF1000. I made a crude drawing using the receivers schematic with the added trimmer to hopefully show what he is talking about (as a general idea only). But the usual warning for anyone attempting this you are "totally" on your own and risk.

"If you look on page 4 of the "Digital" board schematic, up in the right corner you will see the Line level outputs. Just before the transformers you can see the Amplifier IC's (NE5534). There is a 22K Ohm feedback resistor which sets the output level. Attached to one side of this resistor is a 2.7K Ohm resistor, the other side of the 22K resistor has a line going, along with the output side of the 2.7K to J6 a 4 pin connector (not installed)(Labeled REMOTE GAIN...Gee) which  can be used as a connector to add a vaiable resistor in parallel with the 22K ohm resistor to reduce the gain of the IC and thus lower the Line Level output. The holes for the connector are visible in your "Unknown" picture of an HF-1000 (see main page for the 8711). Look just to the left , inboard, side of the output transformers for the four open holes. I think the 2.7K is only in line to prevent you from shorting out the Amplifiers. BE SURE THEY ARE IN PLACE...of course if they are missing then you WILL have to add them... If you start at about 50K- 75K you should be in the right area. This should be a little cleaner than an external box."

Repair of a HF-1000 Power Supply

Rick Warnett from downunder has made a successful repair on his Watkins Johnson HF1000's power supply. The Condor SP1348(A) "Custom" power supply is used in the WJ-8711 series receivers as well.

The part failure was a capacitor (C31) that shorted right near the (U3) 7912 12 volt negative IC regulator. It's a 10 uf @ 63V rating, electrolytic type.

Anyone who owns a WJ HF-1000 or WJ8711 series receiver already knows a schematic of this Condor SP1348(A) power supply is missing in the manual for these sets.

Thank You Rick for this most useful information.

Observation with WJ-8711 "Technical Data Sheets".

Here is an observation that I made while doing a bit of comparison between an older "Pre-2003" technical data sheet vs. one dated January 2003. Can you spot a difference?

Taken from a PRE 2003 "Data Sheet" for Speaker Output Specs
Speaker Output
Number of Outputs ........................................................1
ISB mode: USB & LSB selected individually or combined.
(Internal speaker optional)
Bandwidth ......................................................................100 Hz to 13 kHz
Output Level ..................................................................Adjustable up to 1 W into 8-ohm load
Total Harmonic Distortion ..............................................<3% at 1 W
Connector Type .............................................................Screw terminals

From a "Data Sheet" dated Jan 2003 (Signia) (350K)
Speaker Output
Number of Outputs .................................................... 1 output.
For ISB mode, select USB & LSB individually or combined.
(Internal speaker optional)
Bandwidth .................................................................. 100 Hz to 13 kHz
Output Level .............................................................. Adjustable up to 500 mW into 8-ohm load
Total Harmonic Distortion .......................................... <3% at 1 W
Connector Type ......................................................... Screw terminals

OK, can you tell a difference between these two? I sure do. The PRE 2003 data sheet showing the SPEAKER output level as up to 1 W and the JAN 2003 one giving an 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?

NOTE: 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 eariler data sheet.

My sample was purchased just before (just weeks before 2003), and still has the 1.5 Watt LM388 IC.

Specs on LM388 audio amp IC (180k)

Dave Z. N9EWO

" Hammond Cabinet Info. " (May 2004)

I have been asked a number of times now for information to the "Hammond" cabinet that I have my WJ-8711A in (top of this page). That's a good question too as they make many. Better order a pack of the "rack" mounting screws too as the cabinet does not include any (however it does come with the "speed nut clips") . Here are the details. Additional info can be found on the "Hammond Mfg." web site.

"Hammond" Cabinet Model Number is : RCBS1900517BK1

"Hammond" Package of 4 Mounting Screws and Cup Washers (Cup Washers are Black Plastic) : 1421A

I have found 3 USA dealers where to purchase Hammond products (elsewhere I cannot be of any help, sorry) ?? Mouser and Digikey appears to drop ship, that is they do not have them in stock. Newark is the place where I purchased mine from and usually has them ready to ship (at least at the time I wrote this text). But the price is a bit higher from Newark. Again I found the the prices to vary quite a bit, somewhere in the $ 120. to 150. USD area for the cabinet.

Dave Z. N9EWO

Comments from Others

WJ-8711A Dallas Lankford , rev. 1, 4/21/04

My new WJ-8711A just arrived. I haven’t done much more than unpack it and turn it on. Microprocessor (uP) noise at the higher SW frequencies, but nice and quiet in the MW band. I noticed that the preamp is automatically deactivated below 500 kHz.

Just finished measuring the AM sensitivity at 1.6 MHz (usual parameters). 1.0 uV with the preamp on and 1.3 uV with the preamp off. They may as well have left the preamp out. Of course, a little thing like that…

Do I like the WJ-8711A? You bet. It has the best frequency display I have seen. And the other LED displays are excellent too. The tuning knob is identical to the Racal RA6778C knob, but finished differently (black abodized or powder coated). It has a nice heavy feel to it, and an attached dimple (quite large) for spinning with your finger. The 8711A seems very intuitive and easy to use. The frequency entry, step change, and other features are simply the best of any receiver I have used. I suppose you can customize the BW’s for each mode, but I probably won’t bother because it is so easy to select a BW different from the factory default with the push button selected rotary knob (which, with other push buttons, is also used to select mode, AGC release time, noise blanker setting, and so on).

It appears to have 100 memories, but I haven’t used that feature yet. There are separate audio level knobs for the headphones and speaker. Very nice. The manual specifies 2 Vrms into 8 ohms (1/2 watt) for the speaker output, but I measured 3.5 Vrms (1.5 watts into 8 ohms), and an audio BW of at least 100 Hz to 13,000 Hz at less than 3% harmonic distortion. Connected to a good speaker, it sounds excellent to me. Headphone output through a ¼ inch stereo headphone jack (stereo for ISB, L and R common in all other modes) is specified as 10 mW (presumably rms) into 600 ohms, no BW given. Low impedanced headphones seem to work fine.

Pressing the special function key repeatedly toggles you through various user selectable parameters. In particular, it allows you to choose the release (decay) times for fast, medium, and slow AGC. You don’t have complete freedom to choose, but 10 – 100 mS for fast, 100 to 1000 mS for medium, and 1 – 5 S for slow. I reset mine to 100, 1000, and 3. I haven’t had any hets yet, but the (presumably manual) notch filter is there if you need it. And yes, there is AM synchronous detection if you want it. It is the only feature of the 8711A that is not well implemented. A good AMSD should be transparent to the user, i.e., never lose lock, and lock instantly to the strongest carrier in the passband. The AMSD of the 8711A does not meet these requirements. However, since most people can’t tell the difference between a good slow AGC release time and a good AMSD, it doesn’t really matter. The 3 second release time I chose for my slow release takes care of strongly fading SW and MW graveyarders. And in the rare event that it won’t, the 8711A manual gain control is excellent for those occasions.

Tuning around in CW mode with no antenna connected, I did not find any internally generated spurs from 150 kHz to 10 MHz where I got tired of spinning the knob. I did find one at 125 kHz or thereabouts. This WJ-8711A is the most spur-free receiver I have ever tested, bar none. I wish I could say the same about the LO’s, or perhaps it is the DSP circuits. I don’t really know. But tuning around near a carrier produces all sorts of weak birdies. Most of these are within about +/- 20 kHz of the carrier. But there were additional (presumably 1^st LO) spurs at about +32.5, +72.5, … and -47.5, -87.5, …kHz from the carrier, decreasing slowly in level. These correspond to phase noise of about -127 dBc/Hz when using a 6 kHz BW. So they are not really a serious issue, though I would like to see better LO performance in a receiver of this caliber. It is possible that they are spurs of the internal frequency standard. I’ll check this later. I have been running the 8711A head to head against one of my R-390A’s on some weak signals, and it is a dead heat. I am very pleased with it.

Via the Premium Receiver List :

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 icom7800 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 ICOM756pro2 and 3, the 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 RS6790/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 4.1.10 microcode.  (They are the older 4.1.2 and 4.1.3 microcode, and older motherboard).

Orders new from BAE Systems (now DRS...dave) take about 4-6 months. Almost all the features of the WJ8711A are available -- excepting the change in the roofing filter to 8kHz (I've never noted any difference in adjacent channel dxing between the 16 and 8kHz roofing filters, but there are those that feel this does make a difference).

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 optimise 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 minimised.

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 audion due to possible overloading of the detector.

I have the HF-1000 with the terminal strip (according to WJ, with whom I have chatted on a number of occasions, the latest version), and I can tell you that the audio that comes out the speaker channel (on the back of the rx) is *loaded* with digital hash. On the other hand, the audio coming out of the phones channel (on the front panel) is absolutely clean. So, I use the phones output, either to a sensitive speaker or to the input of an amp, and forget about the speaker channel.

(Speaker output is indeed awash with digital hash, but either rear line output is totally clean. I still found then left "tip" headphone output to contain hash and excessive digital hiss , and was a "last version" sample of the HF1000A as well...DaveZ)

Walt Novinger

The preselector is a tradeoff -- if you are in a strong signal environment (Europe) you'll probably wish you had this. If you use it you will trade a few dB of sensitivity, so unless you are near a strong transmitter elsewhere in the world you won't need it. Installing it is easy. Bypassing is easy --- it gets fed by the antenna via BNC. An output BNC-coax-BNC jumpers it to the normal receiver antenna input. Bypass by switching the antenna to this port).

Don Moman

(DaveZ note: The manual states, the optional suboctave preselector will degrade sensitivity/noise figures between 1.5 to 2.5 db, depending on frequency. The test report that came with my 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 tad of loss with it in line and if you need every bit of sensitivity for a weak signal as stated above by Don it can be bypassed.)

DECEMBER 01,1999

I just got off the phone with W-J Helpline (customer rep David Shane) and learned about HF-1000's future.

1. Production and Support:
W-J is accepting orders on the HF-1000 only to 12/31/99. Production will continue on the mil version (8711A) for the foreseeable future, even after the division ownership transfers to Marconi early in the year. Continued support of the HF-1000A is promised, since it and the 8711A are nearly identical.

Production of the HF-1000 is being discontinued because sales have dropped to about 20/year, making it difficult to justify the expense of marketing two nearly identical products. W-J believes that people who don't already have an HF-1000 will be willing to pay an extra $1000 for the 8711A, or will find an HF-1000 on the used market.

There are no plans to implement the Speech Enhancement Unit (SEU) for the HF-1000, given the availability of excellent aftermarket DSP noise and autonotch filters. Similarly, no remote PC software enhancements are planned, since excellent aftermarket software is available.

2. Differences between the HF-1000 and 8711A:
The two radios are fabricated on the same assembly line using identical circuit boards. There are minor firmware changes. The bezels are different and the cabinet is painted (HF-1000) rather than anodized.

(Update: On a late 2000 version of the WJ-8711A, the front panel is painted and not anodized !!...DaveZ)

3. Firmware Upgrades for the HF-1000:
The latest controller firmware is v.04.01.10. A replacement chip costs about $130 and requires that the HF-1000 have a controller board labelled 797214 (etched on the board and listed in the manual). The earlier board is part 797012, and the latest firmware it can accept is v.04.01.03 (requires a 33 MHz or faster DSP chip). Upgrading controller boards costs about $2000 (!)

Fortunately for those of us with the older board, there are extremely minor operational differences between firmware versions 04.01.03 and 04.01.10. Most of the changes were made for manufacturing reasons (to simplify factory alignment, etc.) rather than to enhance performance. The two operational features are minor bug fixes, one associated with receiver muting, and the other with a remote control command that, when issued repeatedly, can cause lockup. Unless one has specifically encountered these bugs in an application (which rarely happens), W-J doesn't recommend shelling out the $130 for the upgrade chip, even if you have the later control board.

Jim Garland W8ZR

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