[R-390] Stability

[ToddRoberts2001 at aol.com]

In the past I have determined that most of the
initial warm-up drift comes from the main VFO tube V701.
The initial turn-on drift might be several hundred Hz
or nearly zero in the first ten minutes. The other
oscillators are all crystal controlled so their turn-on drift
is fairly low.
 
I found that by swapping several different 6BA6 tubes for V701
I would usually hit on a "good" tube that had nearly zero 
drift from a cold start. Worth trying if you have several
spare 6BA6 tubes available.
 
There may still be some small long-term drift while the 
receiver stabilizes thermally but the main drift seems most 
noticeable in the first ten minutes from a cold start and seems 
mainly due to the V701 warm-up characteristics.
 
73 - Todd WD4NGG
 
 
In a message dated 5/31/2013 12:28:08 A.M. Eastern Daylight Time,  
gordon at n6wk.com writes:

Since I am fairly new to my R-390A, I have a question.
How long does it  normally take from cold turn on, until the Radio is 
stable and no longer  drifts?
10 minutes, 30 Minutes, an hour ?
What is considered normal and  how much can I expect it to drift during 
that  time?
Thanks,
Gordon
N6WK