Thanks guys... Sometimes you need a particular item of military surplus - then find there is no such thing - so you have to roll your own.  hihi.  It was a fun project and does the job.  I run it off a little 12V garden tractor battery in the field.

That PA-109 is really interesting.  It looks as if they just obtained a GRC-109 R or T cast metal case, dropped the guts in and then potted the whole thing up to the gunwales.  Not even a nut on the toggle switch.  Is the "panel" even metal??  Looks very prototype-ey except for the Nems label.
Also, from your description sounds like 2 independent HV supplies, one for R, the other for T to conserve Primary power. (I did the same thing with my DIY...for the same reason).  Interesting.  
Sure wonder who and how the requirements were developed for it.  The PP-2684 6 VDC vibrator supply became harder to power in contested territory once most vehicles moved to 12 volts - (hence the battery cell tap clamps in the accessory kits?) That kind of established the early need for the PA-109..  1965-ish?  Not a problem for the 1950's RS-1 with its identical P/S in the 1950's and plentiful 6V vehicle batteries.

The military requirement for what became the GRC-109 was dated October 1963 but I guess specifying/requiring its own unique 12 VDC supply would have been time and money intensive - so maybe that's when the PA-109 appeared for special deployments?  But I've found nothing about that in the literature...
More mysteries...fun musings..

Thanks,,Tim
N6CC

On Mon, Aug 5, 2024 at 4:53 PM B. Smith via MRCA <mrca@mailman.qth.net> wrote:
Nice job Tim on that HB  supply.
An interesting item about the PA-109 is that as soon as you applied 12 volts it became active.  The main toggle switch was used to go from Receive only mode(OFF)  to Receive and Transmit (ON). When the Toggle was OFF you were in receive mode and they switched off  the HV supply and transmitter filaments and reduced the input current requirements for 12 volts. The inverter circuit ran at 3 Kc.
Z


On 8/5/2024 2:38 PM, Tim wrote:
Hi Breck - The PA-109 is an interesting piece of obscure history.  I've never seen one in the wild and only 1 photo (yours? online).
Essential gear for GRC-109/RS-1 ops, I had to build my own version so I could run the T/R system at 12 Volts these days.  

It (and my DIY) can also run the GRC-9 receiver directly as they emulate the BA-48 battery - same voltages and connector. I built mine in a spare GRC-109 transmitter case.  A fun project.

Cheers, Tim
N6CC

On Sun, Aug 4, 2024 at 3:11 PM B. Smith via MRCA <mrca@mailman.qth.net> wrote:
The Nems Clarke PA-109 has been shipped to another collector.
Z
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