[Boatanchors] ARC 5 stuff - LIST

[J Forster]

jeremy-ca wrote:

> When did YOU ever see a manual for most of the WW2 surplus that was
> released? The smarter hams did a reverse engineering and wrote up the
> circuits and conversion in a series of CQ Magazine articles in the late
> 40's.
> It was strange to see gear released to the public by the tons but the
> manuals were still classified.

I just looked at an original 1945 ARC-5 manual and the cover clearly states it
replaced a 1944 version and is UNCLASSIFIED. Dates and manual numbers upon
request.

It does not take a lot of reverse engineering to figure out that a set with a
series variable inductor connected to the antenna terminal is designed to
connect to a load that looks capacitive, or that antennas on planes and tanks
are electrically short, hence  capacitive. AFAIK, in those days you actually had
to understand a bit about circuits to get a ticket. A series LCR is about as
simple as you can get. Also, the transmitters were often tuned up for maximum RF
amps (eg: BC-442), which is a pretty obvious indication that you were trying to
resonate a series LC.


> Time and again I've read about
> > TVI and other spurious problems in WW II gear when some jerk has the thing
> > grossly mismatched and the B+ cranked up to several times the design spec.
>
> 1500V on an ARC-5 TX? I think not. That didnt even happen with the BC375 or
> ART-13 and the famous BC-610. They were great TVI and harmonic generators
> all by themselves since there was no government (FCC)regulation on military
> gear.

Maybe not 1500 VDC, but certainly in excess of the design spec.

> The designers in WW II were NOT fools.
>
> Nope, they just built to a spec that was handed to them for a very
> disposable piece of equipment. The primary criteria was ruggedness under
> combat use and easy to operate by even a Marine. (I couldnt resist)
> OTOH, commercial gear had to satisfy a much wider criteria of use.

I've seen hundreds of examples of ham hacked gear. Some was neatly done, but the
vast majority was junk. I am generally unimpressed by the capabilities of the
hams of those days.

Commercial gear is often loaded with bells and whistles, so as to give it an
advantage in the market place, but such additions often add little to the basic
mission. The military usually does not buy or spec such frivolities.

> (OTOH, some of the early TV designers might
> > well have been.)
>
> Mad Man Muntz and the Hallicrafters TV come to mind.
>
> Carl
> KM1H

Yeah, and poorly shielded TVs were (and in some cases still are) the root cause
of TVI. Economic pressures forced them to be cheap, and political pull likely
exempted them from EMI emission specs.

FWIW,
-John