CEI
/ Watkins Johnson WJ-357
Nooooo it followed me
home honestly it did……!
See it run at: https://www.facebook.com/tuberadioaustralia/videos/1731142887123653/
At the 2016 Wyong field day one Sunday I picked up another WJ, it
was looking all alone on a table with $100 on it so I offered $40 and got it.
Didn’t have a power plug and the owner said it followed him home
from some gig he had in the UK with the Submarine service.
One again the condition was unknown, so that night I powered it
up, and got it running in rough fashion.
After getting some signals I turned my attention to the issues the
radio had.
These being, the display not working, the noise
cancelling non-functional and the CW / LSB not functional.
As it turned out it needed three resistors in the Nixie Driver boards, as they were open, three out of the
four digital display Nixies were now working,
one had to come from the US and now it’s
operational as well.
The Noise circuit was not working and as it turned out the runaway
of the frequency counter and other issues were all related.
The radio has a number of complex power supplies, a Plus and Minus
12V supply PCB, and another that delivers 4.5 Plus and Minus.
There is also a 200VDC supply to drive the Nixies
@ very low Amps. As it turned out a number of Electros had failed.
Also there were some tubular tantalums that were suspect so they
were changed with LOW ESR electros.
This stabilised the counter display, but every now and then it
would take off. I eventualy tracked this to a fault
in the 1Mhz crystal, a replacement sorted the issue.
After this I had to get the Attenuator sorted, it just needed a
clean, and away it went.
I have been doing battle with the Noise generator, and Balanced
Mixer and they are now working better.
It needs the attenuator in the second click -20DB as the antenna
overloads the front end, but a bunch of LF stations appear.
A very nice set in deed with CEI stamped all over the inside and
WJ on the outside.
Construction of this set was in 1967 and 1970.
The Data Below is the G model, later production,
Mine has white CEI knobs but is essentially the same set. I noticed that the later
set also lost a digit on the frequency display,
mine has 4 with a
decimal point.
Manuals
and Data:
This was very hard to find so here are the links to the
documentation.
Service
Manual and diagrams:
TOC, Sec1, Sec2, Sec3, Sec4, Sec51, Sec52, Sec53, Sec54, Sec55, Sec6
Operational Manual:
The Following Data is from Terry Johnsons
site, See: http://watkins-johnson.terryo.org/CEI-Receivers/357.htm
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The 357 is
one of the greatest VLF-LF receivers ever made. The basic design was released
as a series receivers with different tuning indicators and other features . The 357
and the R-1401 military version are the most common. Production of this radio
continued until well after the California microwave company Watkins-Johnson
purchased Communications Electronics, Inc. The 357
tunes 1-600 kHz with AM-USB-LSB and great IF bandwidths of 150 Hz, 1, 3 &
6 kHz. Other versions may have different IF bandwidths. I have used a 357
side by side with the legendary Collins R-389 and it gave up nothing in terms
of sensitivity. The extreme weight of the R-389 proved an asset only when
near powerful AM broadcast stations. The Nixie tube
frequency display is particularly nice, a big improvement over Veeder Root mechanical counters and zero beat
calibrators. The front
panel is well laid out and operation is self-explanatory, except for the DAFC
- Digital Automatic Frequency Control. When activated, the DAFC locks the
tuned frequency to the crystal timebase in the
counter for exceptional stability. This method gives you the stability of a
digital radio and the quiet analogue circuitry and ease of tuning. The 357
sold for $4200 in 1967, which was about the cost of five brand new VW
beetles. Nevertheless it is one of the more commonly available older CEI
radios because the US government purchased many in many stripes (see
below). |
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The 357 is
unusual for its 2 MHz IF strip (center with blue
filters). It actually has two separate IF strips, one for the signal and a
second for noise detection and suppression. Everything is modular and heavily
shielded, typical of CEI and WJ equipment. |
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The
antenna input (upper left) is unusual for the switchable 50 or 1000 ohm
input. The 340 receiver, which replaced the 357, had a similar arrangement
but used a separate triaxial BNC connector. CEI
made a 2 MHz input SDU, the SM-8421 - a $2500 accessory in 1966 dollars), to
match the 357. |
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The Nixie tube digital frequency display is located on
the left side of the front panel. In standard mode it reads to 100 Hz
accuracy. In decimal shift, it reads to 10 Hz accuracy. The "DAFC LAST
DIGIT" control selects the 100 Hz increment you wish to lock onto (or 10
Hz in decimal shift mode). The DAFC locks the receiver to the crystal oscillator
in the counter timebase. |
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Nothing
beats a Nixie tube for a pleasant attractive
readout. Nixie tubes are neon filled vacuum tubes
with wire electrodes in shapes that light up when a high voltage is applied.
Very cool. |
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There are
many controls on the narrow front panel, but well laid out are very usable.
The noise canceller is much more complex than most noise limiters, boasting
its own IF strip and a gate circuitry rather than the usual simple impulse
limiting diode. |
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The
R-1401A/G is the 357 produced for the National Security Agency (NSA). It is
one of many variations
ordered by the US government. |
|
The bottom
reveals the extraordinary attention to detail in the design and construction
typical for CEI and WJ radios. |
|
The tuning
mechanism relies on a variable capacitor with a varactor for fine ruining and
DAFC control. |
|
The 357
has four crystal filters for excellent selectivity. The 2 MHz centre
frequency is unusual. |
