[R-390] R-390 PTO Warmup Time

[Bob kb8tq]

Hi

Best to simply let the radio warm up for a while. The ovens will heat things in a way that is not “same / same” as normal warmup. Unless things are really cold, you probably will not save a lot of time.

How long does it take for a radio to stabilize? That depends a lot on how picky you are and the exact radio you happen to have. Picky folks just might turn it on a few hours before they need to use it. Very picky folks might turn it on the day before :) :)

If the radio has been in storage, humidity will have had an impact. It will drift longer than a radio that is used on a regular basis. Store it in a damp barn for years and who knows how long you should run it to get it dried out. On some stuff the answer is measured in weeks. I have gear here that the answer is measured in months.

Bob

> On Jul 30, 2026, at 12:30 PM, SCOTT Barry via R-390 <r-390 at mailman.qth.net> 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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