First look at my Watkins Johnson 8718A

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First look at my Watkins Johnson 8718A

Postby 2E0VPX on Fri Aug 13, 2010 10:18 pm

Hi all,

Thought you might like a quick look at the WJ8178A receiver I just received from China.

wj1.jpg
wj1.jpg (33.12 KiB) Viewed 1614 times


Everything seems to be working. Tuning goes down to 0 Khz (even though the manual says 5 Khz) and up to 30Mhz. Reception is fab - certainly quieter than my TS850 which also has a fine receiver. I just love the BIG frequency display...

No clue as to the previous user - all the identifying labels have been taken off, although there is a feint "39" on the front display. The serial number is 3410 and they were first produced in 1976 I believe, so presumably this one is from the late 70's. I do wonder where it came from though - I got it from Shanghai.

No light on the signal meter so I'd like to get an orange LED to backlight it, to match the frequency display.

Audio from the headphone socket is good, but the line out is 800ohm (from the rear) so I'll need an audio transformer to run a speaker. Maybe I'll fit it inside (there is bags of room). Lots of non-standard cards inside too - not sure yet what they do. A bit nervy about pulling them out but I dare say I will eventually.

Pleased with my purchase though - all the way from China in 13 days!
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Re: First look at my Watkins Johnson 8718A

Postby 2E0VPX on Fri Aug 13, 2010 11:49 pm

Investigated the optional cards fitted. They are:

MCM2 - Manual control module
488-2 - IEEE-488 I/O Remote Control
ISB - Independent Sideband
PRE - Preselector
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Re: First look at my Watkins Johnson 8718A

Postby G0GQP on Sat Aug 14, 2010 4:12 pm

:whoopee: Very Nice, You Can Stop Worrying Now :lol:
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Re: First look at my Watkins Johnson 8718A

Postby M0CEM on Tue Aug 17, 2010 9:48 pm

I think you will need a powered loudspeaker - a PC type should do. The 800 ohm (don't you mean 600 ohm? ) output will be line level audio.

Looks very nice indeed. ISB adapter too! So are there two separate audio outputs, one for each sideband? Try listening to AM on a stereo amplifier, or a pair of self-powered PC speakers.

How about bringing it to the shack one weekend so I can have a play with it...
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Re: First look at my Watkins Johnson 8718A

Postby 2E0VPX on Tue Aug 17, 2010 11:18 pm

Hi Dave,

600 ohm, you're quite right. I'll try some powered speakers....

Yes ISB is neat - as you say LSB out of one ear and USB out the other with headphones. Makes AM sound very nice!

Yes I will fetch it in at some point, though it weighs a ton...
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Re: First look at my Watkins Johnson 8718A

Postby 2E0VPX on Wed Sep 15, 2010 10:11 pm

Found this out about my WJ:

Apparently, in the mid/late 80s, WJ sold WJ-8718As and WJ-8718/MFPs directly to China. The technology transfer was a sensitive issue and required approval at the highest level. The sale was tied to certain political efforts. The Chinese specified transport on Chinese military aircraft
for the overseas leg from California. These aircraft were unpressurized and unheated.

Significant numbers of the radio failed almost immediately. WJ sent engineers over to fix the radios. They found the tantalum capacitors were compromised by the flight conditions and failing when powered up. WJ staff spent several weeks recapping the radios in a small conference room of a hotel before the Chinese government accepted the shipment.

Looks like my 8718A (serial no 3410), was probably one of these radios, now decommissioned.

Nice to have a bit of history....
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Re: First look at my Watkins Johnson 8718A

Postby 2E0VZK on Thu Sep 16, 2010 8:21 am

Can you tell if it was recapped?
That might give you some pointers. I would have thought there may be some tell-tale signs...

Come on lets have so photos of the INSIDE :)
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Re: First look at my Watkins Johnson 8718A

Postby 2E0VPX on Thu Sep 16, 2010 8:25 am

I will investigate that, although it is quite hard to see as the radio is built on a series of shielded cards slotted into a mainboard, PC-style. I could take the cards out but it is not for the feint hearted (which leaves me out!) with a 30 year old radio!

I will get some photos up soon....
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Re: First look at my Watkins Johnson 8718A

Postby 2E0VZK on Thu Sep 16, 2010 8:36 am

Ahhh yes, I can see how that could be a problem...
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