[R-390] R-390 PTO Warmup Time

[SCOTT Barry]

Renée,

Yes, I agree that everything has to come up to temperature.  I was just 
thinking if I could mostly eliminate one variable, it might not take 
quite as long to settle.  Right now I'm in my un-air-conditioned shop 
and it's quite warm out here (although the humidity is rather high).

It turns out that my previous measurements were off a bit.  I now have 
the PTO stabilized a bit better and am seeing that 1,000,001.5 kc 
end-to-end so I think I'm going to want to get that closer.  I seem to 
recall setting the overall width a few years ago but it could have 
drifted since then.  Also, I might have done that in a less humid time 
of the year so that could also account for some of it.

Thanks again
Barry - N4BUQ

> 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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