[ARC5] [Bulk] Notes and Tips: RCA AVR-20, AVT-112, AVA-126

[Jack Antonio]

On 10/18/2015 12:33 PM, David Stinson wrote:
> Working with an friend of long acquaintance (blessed to
> know someone smarter than me!) on ressurecting the popular WWII-era RCA
> AVR-20/AVT-112/AVA-126 light aircraft set.


This is a bit of a nitpick, but just thought I'd mention it for the
sake of historical accuracy.

There is an AVT-112, and an AVT-112A.

Both have the capability of field changing the primary voltage
(filament and relay) from 6 to 12V, but the A adds 24V capability.

The front panel of the A version has a changeable tag to show the
the selected primary voltage.

The non-A has the primary voltage engraved in the front panel.

I don't know if there is an AVR-20 with no suffix, the only
documentation I have shows the AVR-20A which shows 6, 12,
and 24V filament wiring.

Something similar concerning the AVA-126 and AVA-126A power
supplies. The AVA-126 is changeable from 6 to 12V, by changing
the vibrator and relay connections. The A version adds 24V capability, 
again by changing the vibrator, relay connections and removing a jumper.

Replacement vibrators are unobtanium. I thought I'd found some on a
website, only to find that the listing was a typo.

My AVA-126A came with a 6V vibrator that had the base rewired for
12V operation. It was so well done, it was not immediately apparent.
It also had the 0Z4 changed to a 6X5(with filament dropping resistor). 
All attempts to restore the unit back to a 0Z4 failed, high current draw 
and low hi voltage output. So the 6X5 and its resistor stayed.

Jack Antonio WA7DIA/4