[ARC5] History of Ham Mods: Opinions?

[Dennis Monticelli]

If the rig is already modified and the relay is missing, you won't
miss its clatter.  It wasn't really intended for keying anyway.  Just
key the PA cathodes and let the osc run continuously (or at least
continuously during transmit).  Regulating the osc and screen via VR
tubes is a very good idea.  The chirp will be manageable if you do
that, but typically won't completely clean up until you also regulate
the plate supply. At least that's been my experience. with a T-22 on
40M.  The chirp problem is less on 80M.  You should also pay attention
to key clicks if you intend to use the rig often.  Simple cathode
keying of the PA will cause clicks.  Standard fixes work to address
it.

There are various ways to attach a knob to the spline.  The method I
used was to start with some plastic rod of a diameter that is a little
smaller than the inner diameter of the threaded shell that houses the
spline shaft.  Cut off about a half inch of rod and drill its center
to a diameter slightly smaller than the outer diameter of the spline
shaft.  Then glue the drilled piece to your favorite knob with epoxy
cement (I used a knob of generous diameter).  After cure you simply
press the knob on the spline shaft.  The sharp splines cut their way
into the plastic and hold fast.  There is no backlash on a knob built
this way, unlike the original equipment knob that fits the shaft.
Once you make one little plastic adapter successfully, you can make
several out of the same rod and save them for when you need additional
knobs.  I've also seen some plastic standoffs that would work just as
well after drilling out the existing screw hole to a larger size.

Dennis AE6C

On Wed, Dec 31, 2008 at 12:02 AM, Jim Hill <hro5-2 at cox.net> wrote:
> Thanks for the excellent tips on connecting to the power connectors.
>
> Here's another useful topic - how do you connect to the splined shaft to
> tune a Command receiver?  I've tried using a pencil eraser (push and twist)
> and forcing a short length of copper tubing over the shaft.  The second
> choice would have worked better if I had drilled out the tubing so less
> force was needed. Years ago, a spinner knob and female spline to shaft
> adapters were available, and I purchased each type.
>
> My personal feeling that totally unmodified sets in good condition should be
> unchanged. Those with some modifications and/or damage can be used, with
> defective parts replaced.   Most reasonably priced available transmitters
> have been modified, usually the under-chassis relay has been removed and
> lost or discarded.  Info about using the set without this relay would be
> helpful.  Years ago,  I ran the oscillator plate and amplifier screen at the
> same voltage from a regulated source using VR tubes and keyed this voltage.
>  The key was hot, but after being zapped a few times I was careful - but
> wouldn't do it now.
>
> Jim
>
>
>
>
>
> At 05:52 AM 6/15/2009, you wrote:
>>
>> Should a collector's guide to WWII radios, which emphasizes the history of
>> the equipment,
>> include a section citing examples of exceptional ham radio mods?  On one
>> hand- it is a part of the history of these sets.
>
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