[ARC5] Army/Navy transmitters from a NON COLLECTOR viewpoint, the ham version...

[Peter Bertini]

The rack is in  poor condition...  I was going to replace one of the
chassis mount males
with one that will properly mate my other transmitters. My problem is
finding a connector, or having
 to make one with the miniature banana plugs I have.on hand.  I don't want
t modify the rack, but having
the "wrong" transmitter in one bay isn't going to bother me.  what is the
part number for the
chassis mount fitting that I need?

On Sun, Feb 9, 2020 at 4:57 PM Mike Everette <radiocompass at yahoo.com> wrote:

> The reason the FT-226 rack does not work with the ARC-5 series is the
> transmitter power plug.  If you compare one of the BC-series or ATA series
> transmitters (either of which will fit the FT-226 rack) to one of the
> ARC-5s, you'll see that the power plug for the ARC-5 is slightly larger and
> with different pin spacing.  It won't mate with the plug in the rack you
> want to use.
>
> Consequently, the power plugs in the ARC-5 series racks don't mate with
> the BC or ATA transmitters.
>
> This was done originally to avoid confusion between the series by
> elinating the possibility of plugging the wrong transmitter into a rack.
> In the case of the ARC-5 transmitters, the wider pin spacing very likely
> has to do with higher peak voltages resulting from plate modulation.  At
> ground level it probably isn't anything to worry about, but as altitude
> increases, the breakdown voltage decreases.  In unpressurized WW2 aircraft
> this was a real concern.
>
> In my opinion, and I'm sure that of many others on this group, learning
> the details and the ins-and-outs of these various systems is part of the
> fun.... But of course the real fun is getting these radios on the air.  I
> think you are on the right track with this.
>
> Beware!  This all can lead to a disease called "ARC-5 Fever."  Who knows
> where you'll wind up.  One day you just might want to put together a
> complete system.  Or not.  Just have fun with it.
>
> A hint on getting the radios on the air:  You can use miniature male
> banana plugs to mate with the original power connectors.  There was an
> article in QST Magazine about 5 years or so ago about the transmitters
> which pointed this out.  No need to change the socket to an octal plug as
> was common in the 50s and 60s.
>
> 73
>
> Mike
> WA4DLF
>
>
>
>
>
>
> On Sunday, February 9, 2020, 12:55:40 PM EST, Peter Bertini <
> radioconnection at gmail.com> wrote:
>
>
> I'm probably in the wrong group... but...
>
> Beyond the bewildering confusion deciphering between ARA/ATA, CBY/CCT,
> SCR-274, BC-xxx, T-xx/ARC-5 variants... I am looking for a common
> denominator..
> Assuming one  is NOT interested in the correct accessories, cables,
> modulators, dynamotors, etc...
>
> And for the sole purpose of putting any variant on the air with minimal
> modifications to transmitter itself... don't want
> shelf queens, I want these to be usable and on the air.
>
> 1: Can either variant be either screen or plate modulated? I don't see
> anything that would preclude doing so..
>
> 2: Any suggestions on how a beat-up FT-226-A tray might accommodate either
> style transmitter? I am thinking having each
> rear connector wired for a particular transmitter pin out, but how to
> avoid accidentally putting the wrong version in the wrong
> slot? One side Army, one side Navy...
>
> 3: For power... a modified Heathkit PS-23 junker... get rid of the voltage
> doubler nonsense and use full wave bridges on the
> high and low voltage windings. Series the two to provide around 125 vdc
> for the RX, and around 500 vdc for the TX.
>
> 4: Add a half-wave voltage doubler on the 12.6 winding for DC filament
> voltage for the transmitter filaments and relays.
>
> 5 Any benefit to regulating the 200 VDC for the 1626 oscillator? I suspect
> it would not hurt.
>
> 6: transmitters will be modified following AB5S's suggestions regarding
> relay adjustments, etc
>
> Flame away...
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