[Boatanchors] AM-8C/TRA-1 amp power supply info needed...

[WA5CAB at cs.com]

Mike,

Are you sure that you mean 600 Meters and not 6 Meters?  The AN/TRC-1 that 
the AM-8/TRA-1 is used with covers 70-100 MC FM.

In any case, the power supply for the AM-8(*)/TRA-1 is the PP-13(*)/TRA-1.  
The AM-8 has three VR-150's in it connected across the 4E27 screens to regulate 
their voltage at 450 VDC.  The PP-13 output is -100 VDC fixed bias for the 
4E27 grids, +1900 VDC @ 250 MA for the plates and 450 VDC @ 40 MA for the 
screens.  The +1900 VDC line has a 35K resistor connected to a 25K resistor which is 
connected to -1900 VDC.  The +450 VDC is taken from the junction of the two 
resistors.  The B- goes to pin C on P204 on the AM-8.  From there it goes to 
the cathode of the bottom VR-150 and to the antenna transfer relay coil RL-201 
and to ground.  +1900 VDC goes to P205.  And -100 VDC goes to L on P204.  
P204-H is Ground.  

The manual for AN/TRC-1 and AN/TRA-1 is TM 11-2601 (several editions).  
Unfortunately, I only have one of each but if you can read a TIF file I can send 
you the schematic of the AM-8 and PP-13.

In a message dated 9/24/2007 3:08:09 PM Central Daylight Time, we0h at yahoo.com 
writes: 
> Does anyone know what voltages the screen &plate are for this 
> amplifier? I am modifying one for 600 meters and have no clue what I 
> need to build for a screen supply or what voltage the amp should have on 
> the plates.
> 
> Would it be as simple as using the tube datasheet suggested voltages for 
> the class of operation it will be setup for?
> 
> 

Robert & Susan Downs - Houston
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