[R-390] R-390 PTO Warmup Time

[Renee K6FSB]

Barry-
that seems about correct however, there are some environmental variables 
in play. temp from start and actual final temp in working 
location...humidity will also impart its coefficient depending on time 
since last "real" use.
stability depends on what is acceptable to you and your environment. The 
rest of the radio needs to also stabilize and it is not "ovenized¨
Renée

On 7/30/26 9:30 AM, SCOTT Barry via R-390 wrote:
> While I know the manual states that the receiver should be allowed to 
> warm up (30 minutes?), I wonder how long it should take for the PTO to 
> stabilize.  I have the PTO out and monitoring the frequency from cold 
> and it takes quite a while to stabilize - maybe 15 or 20 minutes.
>
> It climbs until it reaches a certain frequency and then starts very 
> slowly up and down a few hundred Hz before settling down to a 
> reasonably stable frequency.  Before I took it out, I was seeing 
> end-to-end about 1,000,001.5 kc so I thought it may need a touch-up on 
> that; however, I don't think I had let it warm up sufficiently because 
> if I let it warm up a good while, it is much closer to 1,000,000kc 
> end-to-end (approximately 1,000,000.300kc), hence my wondering about 
> warmup time.
>
> Any thoughts on this?  Would running the oven for about 10 minutes and 
> then turning it off help stabilize it faster?
>
> Thanks,
> Barry - N4BUQ
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