[R-390] R390A / R390 help

[Roger L Ruszkowski]

Hello Everyone,
I have a question, how does the R390 and R390A compare as to sensitivity?
73's Lee.
-----------------------------
Lee,

From 68 through 75 I took care of many thousands of R390/a and a few R390
all around the Pacific Rim. I have found either species of receiver to be
about
equally insensitive to GI's, Sailors, Marines and Airedales. When falling
on
fingers and feet I have never know a receiver to apologize for the clumsy
act.
The receivers are prone to popping a tube filament open at the most
inopportune
time with out a care as to how it impacts our plans. The receivers will
split a
gear clamp or strip a spline screw at the though of a maintenance
procedure.
These receivers can be as insensitive as any other living pet. I think the
47 Ohm resistors in the R390 power supply circuit can treat you with even
more contempt than any cat I have known.

Text book wise the receivers are equal in receiver sensitivity.
Having cared for and watched op's use them for years of military service
the two are so close you can not tell them apart.
An R390 and an R390/A set up side by side in rack and coupled to some
of the best antenna the Military could build yields equal number of
signals.
One is not more hard or hearing than the other.

The mechanical filters in the R390/A ring. The stock R390 sounds a
little better on AM than the R390/A  The two stage R390 RF does
not produce any better response in the head phones than the
single 6DC6 in the R390/A RF amp.

Ethiopia, Turkey, Berlin got the first R390's. The R390/A went to
Viet Nam, Okinawa, Japan, Korea. I had R390's in Korea with
28 Volt DC power supplies that were run off the 28 Volt truck
generators. We had gas engines and heavy duty generators
in the 2 1/2 ton trucks. The trucks had cargo boxes (vans) mounted
on them and filled with radio's. You could run the radio's off the
truck generators (battries). We also had smaller engine generators
that used a lot less gas and were much quieter than the truck
engines.

These things were mostly in retirement by 1971 in Korea.
But hey there was a war on over there and had been since the
early 50's so we were ready to go to the field.

Worry not if its a R390 or R390/A, you do not have enough
of them either way. Keep what you can get.

Roger KC6TRU.