Heat Related Frequency Drift 6300

Ben - AE4NT

BTW, Rick, I typically run 20W or so when doing JT-65 unless conditions warrant more power. I never run full power. My SWR is < 1.2:1.

Ben - AE4NT

Thanks, Michael, for the definitive word straight from K1JT-ville. Knowing about the drift compensation, I won't be so put off by the leaning lines on the waterfall and perhaps I'll save five grand, too!

73,
Ben - AE4NT

Tim - W4TME

Ben, with a TCXO, there will be some frequency drift if the XO is exposed to a sudden increase in temperature, such as when you are transmitting.  

I'd go to the website and fill out Flex Trade-UP! / Trade-IN! Form and see what type of credit you can get for a 6500 +GPSDO

G8ZPX

Ben, one small positive is that the laptop cooler can run directly from the USB on the f6k. Finally found a practical use for that otherwise dead connector!

Ben - AE4NT

Aha! Thanks, Steve!

Tim, I did that yesterday. I find lots of ways to spend money, but this one might be a stretch. If they have seriously sharpened pencils, I might consider it.

73,
Ben - AE4NT

Cal N3CAL

Here's a snapshot of Ben's (AE4NT) JT-65 signal on 6m this afternoon. The snapshot is after 30 minutes of watching him work stations....   You can see he's starting to drift...



Cal/N3CAL

Ben - AE4NT

P.S.
Can the same be said for JT9?

Michael Coslo

Hehe Ben, that reminds me - I made a deal with the missus to get my flex (the so called lowly 6300) and in return, I remodeled the kitchen, repoured the patio concrete, built a new pergola over it, bought and installed a new spa, and next is remodeling the great room. Looks like I'll have spent 50+ k and a lot of time for a 2500 dollar radio. 

Shoulda at least held out for the 6700.

Ben - AE4NT

Michael, I'm thinking that a 6700 would have cost you a new house for the distaff approval!

73 de AE4NT

Michael Coslo

Why would you want that Ben? Pencils are pretty inexpensive. I suppose Flex could send you a pencil along with the new radio though......

George KF2T

That seems like more drift than I'd expect. Not world-ending, but still odd. Ben, do you leave power on the rig all the time, or do you shut down the 12V supply when not using the rig? I have a non-GPSDO 6500, and don't see anything remotely like that. Granted, different rig.

Ben - AE4NT

BTW, the heat situation seems to be significantly worse in the VHF range. I, too, can operate JT65 at higher power levels on lower bands and never hear the high fan.

Ben - AE4NT

But pencils don't overheat if you subject them to heavy duty cycles. 

Ben - AE4NT

My 12V supply is always on. It is an Astron RS-70M, which has proven to be quite stable.

The drift is understandably magnified proportional to the frequency, so it is not glaringly obvious on 40M or 80M, for example. I can just begin to see some on 20M and what you see in Cal's screenshot represents the 6M extreme.

Your 6500 is a different rig, but the 10 MHz reference clock stability spec is the same as the 6300, 0.5 ppm. On the 6700, the spec is 0.02 ppm.

Thanks for your thoughts.

73,
Ben - AE4NT

Ben - AE4NT

Well, after opening a support ticket, Tim did some tests with a baseline 6300, and compared his readings with mine when I duplicated the tests here. Conclusions:

1) My 6300 performance was nominal, both case temp and frequency drift.
2) The laptop cooler recommended by Steve G1XOW didn't have a material effect on the case temp while transmitting, but it cut the recovery time to original ambient temperature during subsequent receive cycle by 50%. So, overall, operation will be cooler with the increased air flow.
3) You all talked me into doing the Trade-Up deal for the 6500, so I ordered one. Thanks for making me spend the money. I hope you're satisfied now.

Tim, as usual hopped right on this and did what he needed to do to make things right. And he didn't try to talk me out of the upgrade.

73 de AE4NT

Jay Nation

Ben

I'm guessing 6500 with GPSDO.
One less thing to worry about adjusting.

73, Jay - NO5J

KY6LA_Howard

Yes  Blame that upgrade on everyone else

BUT we all know you secretly wanted to do it...