OK, folks, I took the plunge and bought a "AS-IS but not DOA"
Watkins-Johnson WJ-8716 on E-bay.

For those who haven't used or seen them before, this is not a SW
portable. This is not a SW tabletop. This is a rack-mount receiver sold
in the 80's to the military, certain 3-letter agencies, certain
laboratory environments, etc. My particular unit has the GPIB
interface, the Preselector, ISB, and the regular (not microprocessor)
front panel.

The seller wasn't particularly communicative nor awfully quick to ship,
but after a week it got sent via UPS and arrived safely. Packing job
wasn't stellar but it was good enough (and after all these things are
pretty sturdy).

Just for a base of comparison: I've owned many SW receivers over the
years. My first was a Knight-Kit Space Spanner. Since then I've had an
assortment of ham and SW equipment - if you can name a brand, model, or
seller, I probably had at least some contact. Usually I stay away from
the newest and shiniest stuff, and in the past couple years my main
pieces of equipment were some R-390A's and the associated
electromechanical maintenance. I was very happy with the R-390A's as AM
and CW receivers, but they predate modern SSB stuff and the lack of a
product detector was a sore point. R-390A's are also a true joy to work
on - modular construction, nice big glowing tubes, a geartrain and cams
up the wazoo, the works!

But I made the plunge and got the WJ-8716 anyway. Even though it is
"digital", it's not newfangled digital, it's 20 years oldI unboxed it,
plugged it in, and it worked.

Then (of course) I took off the cover. The microprocessor board had a
good amount of damage from a NiCad battery that had leaked all over it.
I pried off the battery, put it in an acid bath to neutralize the gunk
that had leaked from the battery, scrubbed off some/most of the
corrosion, rinsed it and let it dry off. Well, it had 10 years worth
of damage from the gunk probably (the radio is 20 years old and I'm
guessing the leakage started a decade ago) but at least that damage had
been stopped from continuing.

Now I get to play with the radio hooked up to an antenna. WOW. This is
amazing. It's got 5 filters (300 khz, 1 khz, 3.2kHz, 6kHz, and 16kHZ).
The filters have the sharpest edges I've ever heard, and I've used a
lot of ham and communications receivers over the years. If there's a
hetrodyne, I just shift the center frequency or put on a narrower
filter and that hetrodyne is GONE. Maybe every other crystal filter
I've ever heard before is crap, but I doubt it, most of them are pretty
good but they don't make a hetrodyne that's 9 S-units above the desired
signal and a couple hundred Hz away disappear like that!

It doesn't officially have passband tuning in the modern sense but it's
got a dial-in BFO offset and the different filter widths, and between
the two I do just fine. Those who have used modern receivers without
BFO knobs will probably have to learn the skill. My one caveat: I do
not particularly like the thumbwheel BFO setting. I much prefer knobs.

Now, the tuning: My wrists are rather strong after prolonged usage of
the R-390A's :-), but the WJ's big tuning knob works just like I'd
want, smooth and precise with a nice spinner. The tuning steps are
adjustable from 10kHz down to 10Hz, and I might've chosen different
step sizes (on the SW bands a 5kHz step would've been nice) but they're
workable.

Compared to any modern digital-display receiver, there are no bells and
whistles. No memories, no bands, no scanning, no nothin'. That's fine
by me, but others will miss their bells and whistles.

Internal modularization and construction is simply superb. No other way
to describe it. Everything comes out on BNC's on the back, even the
audio.

I'm guessing that this receiver must have a OCXO or at least a TCXO in
its master oscillator, because frequency display is spot on from top to
bottom, from turn on with zero observable drift during warm-up.

Reception on USB and LSB is superb. A couple spot checks of RTTY and
utility frequencies, as well as tuning around the ham bands, were
wonderfully simple and spot-on.

No synchronous AM detector, which some may miss. I have some but not
very much experience with synchronous detectors, so I don't really miss
them. I do occasionally hit the "USB" or "LSB" button when there is
interfence to one side or the other, and that works

Audio quality is also excellent. I use a little outboard amplifier and
some RatShack Minimus-7's. This is also a very quiet receiver - no hiss
or hum at all. (My ears are particulary picky about hiss).

The receiver is also very well shielded and the preselector seems to do
its job very well. I have a sizable AM broadcaster in my backyard and
most consumer receivers have intermods and images of it showing up
everywhere across the spectrum. My R-390A did a lot better but if I
knew where to look I could find the images (although weaker). On the
WJ-8716, no images anywhere. And I know where to look.

And as far as shielding, if I unhook the antenna then all the signals
go away. Even that AM broadcaster in my backyard, which is strong
enough that I'm sure some could pick it up on their dental fillings.

Still to explo LW reception (I don't think it really goes down to DC
but it basically goes there). It does a superb job on 160M ham band and
on the AM broadcast band, though, so I suspect it'll do fine. And maybe
I'll play with the GPIB computer interface someday.

Tim.

On 2 Feb 2006 09:21:03 -0800, wrote:



Now I get to play with the radio hooked up to an antenna. WOW. This is
amazing. It's got 5 filters (300 khz, 1 khz, 3.2kHz, 6kHz, and 16kHZ).
The filters have the sharpest edges I've ever heard, and I've used a
lot of ham and communications receivers over the years. If there's a
hetrodyne, I just shift the center frequency or put on a narrower
filter and that hetrodyne is GONE. Maybe every other crystal filter
I've ever heard before is crap, but I doubt it, most of them are pretty
good but they don't make a hetrodyne that's 9 S-units above the desired
signal and a couple hundred Hz away disappear like that!

I doubt it's the filters themselves as much as the lack of leakage
around them.

David wrote:
On 2 Feb 2006 09:21:03 -0800, wrote:



Now I get to play with the radio hooked up to an antenna. WOW. This is
amazing. It's got 5 filters (300 khz, 1 khz, 3.2kHz, 6kHz, and 16kHZ).
The filters have the sharpest edges I've ever heard, and I've used a
lot of ham and communications receivers over the years. If there's a
hetrodyne, I just shift the center frequency or put on a narrower
filter and that hetrodyne is GONE. Maybe every other crystal filter
I've ever heard before is crap, but I doubt it, most of them are pretty
good but they don't make a hetrodyne that's 9 S-units above the desired
signal and a couple hundred Hz away disappear like that!


I doubt it's the filters themselves as much as the lack of leakage
around them.


I use crystal filters designed for the Racal 6790 in my AOR 7030+. The
shape factor is 1.33.

Typically, filters with a shape factor of below 2 are considered "pretty
good", and Kiwa is proud of offering premium filters for my radio with a
shape factor of 1.65.

Nice report but you didn't say if the 8716 is better than the Space
Spanner? ;-)


wrote:
OK, folks, I took the plunge and bought a "AS-IS but not DOA"
Watkins-Johnson WJ-8716 on E-bay.

For those who haven't used or seen them before, this is not a SW
portable. This is not a SW tabletop. This is a rack-mount receiver sold
in the 80's to the military, certain 3-letter agencies, certain
laboratory environments, etc. My particular unit has the GPIB
interface, the Preselector, ISB, and the regular (not microprocessor)
front panel.

The seller wasn't particularly communicative nor awfully quick to ship,
but after a week it got sent via UPS and arrived safely. Packing job
wasn't stellar but it was good enough (and after all these things are
pretty sturdy).

Just for a base of comparison: I've owned many SW receivers over the
years. My first was a Knight-Kit Space Spanner. Since then I've had an
assortment of ham and SW equipment - if you can name a brand, model, or
seller, I probably had at least some contact. Usually I stay away from
the newest and shiniest stuff, and in the past couple years my main
pieces of equipment were some R-390A's and the associated
electromechanical maintenance. I was very happy with the R-390A's as AM
and CW receivers, but they predate modern SSB stuff and the lack of a
product detector was a sore point. R-390A's are also a true joy to work
on - modular construction, nice big glowing tubes, a geartrain and cams
up the wazoo, the works!
snipped

You like that Watkins Johnson Radio,do you? I have said it before,I
believe Watkins Johnson Radios are the best Radios in the World.Maybe
some day,I too will own a Watkins Johnson Radio.
cuhulin

What kind of acid bath stuff did you dip the corrosion part of the radio
into? You didn't dip the whole radio in there,did you? I once found a
can of CRC-222 in a scrap metal/junk yard.The spray can only had a
little bit of CRC-222 stuff in the can.That CRC-222 was amazing at
getting rid of battery corrosion.I can't find it in any of the stores
around here,I even checked with the industrial supply stores around
here,they dont sell it.I have a tube of stuff here that is suppose to be
good at preventing corossion.It says on the tube,CONTAX.Blackburn 1525
Woodson Road St.Louis,Missouri.OXI E.Inhibiting Compound.Protects all
electrical connections.Cat No CTB.Instructions.Wire brush the bare
connector or abrade with emery cloth.This may be done through a coating
of Contax or immediately before applying Contax.Apply a liberal coating
of Contax to both the cleanest connector and contactor and surfaces of
the contactor.Insert conductors into connector and secure per
manufacturer's instructions.Wipe off any ecess Contax compound.CAUTION:
Do not abrade plated surfaces of connectors.

I guess it's good stuff,I found it in a scrap metal/junk yard about
twenty years ago.
cuhulin

wrote:
OK, folks, I took the plunge and bought a "AS-IS but not DOA"
Watkins-Johnson WJ-8716 on E-bay.

Do you have the microprocessor front panel version or the standard?


--
Brian Denley
http://home.comcast.net/~b.denley/index.html

Brian Denley wrote:
wrote:
OK, folks, I took the plunge and bought a "AS-IS but not DOA"
Watkins-Johnson WJ-8716 on E-bay.

Do you have the microprocessor front panel version or the standard?

Standard. No memories, no bands, no scanning, etc. Just set the tuning
rate and spin the knob.

Tim.

wrote:
What kind of acid bath stuff did you dip the corrosion part of the radio
into?

Kodak stop bath, which is acetic acid with an indicator. Pretty much
the same stuff as vinegar (maybe a little less flavor!)

You didn't dip the whole radio in there,did you?

The damage was limited to the board that had the battery, plus just a
little bit of crud on the edge connector (not actually on the contact
part.)

Adjacent boards didn't show any damage.

Tim.

HFguy wrote:
Nice report but you didn't say if the 8716 is better than the Space
Spanner? ;-)

Only much later did I ever appreciate the simplicity and sparseness of
the Space Spanner :-).

Tim.