[Premium-Rx] WJ-8711A or WJ-8712P

Wed Jan 2 10:21:10 EST 2013

Hi you two,

Oooh this takes me back. Some of you will know that I ran an EMC (EMI) test
house in the UK so had a lot of experience with MIL 461 and the
corresponding EU standards. I tested one particular US made (not WJ)
receiver that was marginally within radiated emission limits when sitting in
lonely splendour inside an anechoic chamber, but I had observed that in
actual use the noise level from the speaker rose significantly when you
actually sat and used it. I re-ran the radiated emission checks with me
sitting quietly in the test chamber with my right hand resting on the
encoder knob - you can guess what happened. The darned receiver was so far
above emission limits that it did not even qualify as an industrial product
and had to have considerable work done before daring to release it to the
market. It's still there being sold.....!

Give me an analogue beauty every time. The hell with shaft encoders and
scanned displays that radiate from here to eternity. Who said "The truth is
out there somewhere".
John Wilson
G3PCY/5N2AAC

-----Original Message-----
From: premium-rx-bounces at mailman.qth.net
[mailto:premium-rx-bounces at mailman.qth.net] On Behalf Of
richardreich at aol.com
Sent: 02 January 2013 15:04
To: Steve Pappin; premium-rx-bounces at mailman.qth.net;
premium-rx at mailman.qth.net
Subject: Re: [Premium-Rx] WJ-8711A or WJ-8712P

Hello Steve.

I'm not going to blast you.
On the contrary, I like to hear those snippets of privileged information
that normally only come by as rumours.
I could tell you a few eyebrow raising stories about Marconi before they
faded away.

Although my 8711 (on the front panel and labelled HF1000 on the back) has
given problems, I am still very happy with it. Its great to use - especially
when compared to the modern trend of having one knob or button having
several functions - soooo irritating when trying to do something in a hurry.
The 8711 doesn't perform quite as well in the reception stakes as a recently
aligned Racal RA1772 - but then few receivers do.

Happy New Year

Richard
Sent from my BlackBerryR wireless device

-----Original Message-----
From: "Steve Pappin" <pappy92651 at yahoo.com>
Sender: premium-rx-bounces at mailman.qth.net
Date: Tue, 1 Jan 2013 15:06:28 
To: <premium-rx at mailman.qth.net>
Subject: [Premium-Rx] WJ-8711A or WJ-8712P

I have been fielding a lot of questions about the WJ-8711A. People want to
buy them, have them repaired, upgraded, or sell them. I will probably get
blasted for this putting this information out but here goes. The 8711A was
designed as a low cost receiver and it is often not cost effective to
repair. The evolution of the 8712 and 8711 saw many refinements. Most of the
updates for the 8711A were implemented to deal with significant performance
issues. In the end only the 8712 survived because it was the only clean
sheet version that performed entirely as intended. WJ released the 8712P to
replace the 8711A.

The 8712P is a clean sheet version of the 8711A that does not have the
problems. It meets MIL-STD-461 when installed in a metal chassis.The 8711
was an after thought. When the 8712A first came out there was a small
requirement for units with a front panel. WJ very quickly spun up the low
cost 8711 and it had a lot of problems. It was never meant to go into high
volume production. WJ finally redesigned the 8711A as the 8712P. The 8712P
is everything that the 8711A was supposed to be. It is a solid and serious
HF receiver that meets the stringent requirements of MIL-STD-461 when
properly installed. It is basically the new 8712A with a robust front panel.

I can offer the 8712P with options. Take a look at the 8712A data sheet
which lists all the options. The only significant difference between the two
is that the 8712P has a front panel. Options include a pre-selector, rack
mounts, and more. 

I will still support the 8711A on a limited basis, but it is becoming harder
and very expensive to provide new parts. A new front panel sells for
$4000.00. DRS is reluctant to respond to requests. They would like to see
the 8711A go away. The design has many weaknesses: front panel switches,
encoders, power supply, radiated noise, too many firmware versions, etc. The
8711A was their VW. It was designed as a very low cost receiver for COTS
applications, and thus the HF-1000. It was design to last for 10 years
maximum.

What about the 8711A? If you can find one that is new or one that has low
mileage they are a good deal. The final versions have plastic encoder shafts
that do not radiate. The switches are still the same low cost ITT-Schadow
carbon types which are not serviceable. The switching power supplies last
for about 10 years. The final build of 8711A's rolled off the assembly line
last month and went to a government contractor. There will be no more. New
parts are available but they are very expensive.

My opinion: The 8711A is a great receiver if it is a later version, has low
mileage, and has been treated well. They are not easy to repair. New hard
parts and assemblies are very expensive. Firmware upgrades are not
compatible across all radios and in some cases will render the radio
unusable.

I'm currently working with an agency that is replacing their 8711A's. The
failure rate jumped to a very high level right at the 10 year mark. 

Best Regards,
Stephen Pappin

PCS Associates
5621 Palmer Way Suite A
Carlsbad, CA. 92010 USA
Phone: +1-760-487-8951

Online: http://www.pcs-associates.com
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