It seems curious that you need to ventilate the cabinet to control drift.
My Icom IC-765 (sorry to be using bad words here!) with its internal
switching power supply is almost completely sealed with no interior air
flow or ventilation to speak of. I operate it 24/7 on a computer UPS in
order to keep the calibration, etc. stable with little or no discernible
drift. The cabinet runs very slightly warm on top. The external heatsink
seems to do an adequate job - with its internal fan - of dumping excess
heat while transmitting.
Stability is more than adequate for routine ham operating without the
24/7 mode, but since I work digital modes, etc. it is convenient for the
radio to always be stable whenever I want to operate.
What does TT say about the drift vs ventilation situation? Are their
radios not designed to be operated without external cabinet ventilation?
I am not trying to slam TT radios - just curious . . . ;^)
72/73, George AMA 98452 R/C since 1964
Amateur Radio W5YR, in the 54th year and it just keeps getting better!
AutoPOWER Systems, Fairview, TX (30 mi NE Dallas) Collin County
QRP-L QRP-ARCI FISTS NORCAL ZOMBIE ARS 10-X 33.2 N 96.6 W EM13RE
Steve Ellington wrote:
>
> I think most TT rigs are air deprived. The Omni 6's I had needed some air
> inside badly. When receiving, it was stable but after sending for a few
> hours at high speed, the oscillators would drift due to heat conducted
> from the finals. There were 2 cures. One was to keep a fan blowing across
> the heat sink on the outside and my final cure was to remove the speaker
> and install a small fan in the bracket. It fit perfectly and blew air out
> the speaker grill. I used a 24v fan from an HP printer. It was virtually
> silent and stopped the drift. When I sold the rig, I simply removed the
> fan and put the speaker back in it. The corsair and Omni A-D series were
> sealed up with no velilation too. The same thing happens with them after
> transmitting for a while and I'm going to do something along the same
> lines. A cheap solution is to leave the lid off but maybe one could get
> the lid perferated somehow. About 200 holes would do the trick.
--
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