[R-390] Collins R-390-A Photos sought

[Flowertime01 at wmconnect.com]

Tom,

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Did the Collins produced 390a's have the same power cord
as the non-A? or were they built like the subcontracted versions with
the power cord attached and not using a connector like the R-391?
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R390/ A power cords are still different from the R390 power cords.
R390/A only operates from 120 or 240 AC.

The R390 has an alternate power supply and power cord to operate the receiver 
from 24 volt DC power. @RARE at . I only seen a couple receivers in a truck 
mounted van in Korea about 1971 that operated from a 24 volt generator. They were 
old then.

The power cord was wired into 24 Volts. and the power supply was changed.
The power supply bolted in and mated to the existing wire harness.
There was a small dynamotor for B+ and the filaments were all arranged in 24 
- 28 volt strings. The power supply chassis mated the dynamotor and wire 
harness connector to the receiver mounting points. The big series power regulator 
in the Audio deck filtered the B+ from the dynamotor.

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It's missing about half the tube shields.
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Most receivers did not have the tube shields with the metal sleeve inside.
Fellows have done some testing. The sleeve actually runs the tubes cooler than
the plain stock tube shield.

Standard procedure by directive was to run with a minimum tube shield set.
OCS, mixer, Rf amp, and IF tubes got shielded every thing else was run bare.
We had boxes of pulled shields because if we shipped a receiver we had to 
restore its full complement of shields.

Any good photo of an R390/A Collins will show the silver tube shields.
The black shield and sleeve shields are after market add ons.

Shield the VFO, BFO, 6AK5's, 6DC6, 6C4's, the 5814's on the RF deck, 5749's 
and 6AK6 on the IF deck.

Run the 5814's in the IF bare. 
Run the 26Z5 bare.
Run the audio deck bare.

If you have the after market better tube shield, cover these tubes first then 
cover any other tube you have a shield to fit. The sleeved shields do run 
cooler than the silver cans. If you have the better shields then use them. If all 
you have is the silver cans, you are better off running the tubes bare. You 
likely do not run enough equipment in your "shack" to have an interference 
problem from a radiating ocs tube.

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Lucky Fellow,
Enjoy your receiver.

Roger AI4NI