I had some questions about putting a fan in the Omni-6.
First: Excuse me TenTec but I feel that the cooling is just a tad
indaquate in this outstanding rig. After a long cw qso at full power,
heat seems to conduct from the finals to the inside and raise the
temperature. There's probably no harm in this except for a little drift
of the oscillators on the tx/audio board, especially the bfo.
Let me say also that the lack of a cooling fan is a refreshing breeze.
Pun intended. Even the smallest (IC-706) import rigs have noisey little
fans whirring away to keep their little finals cool. TenTec's big heat
sink really does the job. The problem is just one of adaquate venilation
for the insides.
My fist thought was to just leave the lid off. Doing this worked great
and virtually eliminated the bfo drift over long periods but it looked
kinda red-neckish. I considered cutting a huge chunk out of the lid and
replacing it with screen mesh (which is really what it needs) much like
the old Drake equipment. Not being a machinist, I gave up on that idea.
Perhaps some of you may consider it. Order a new lid from the factory
first just in case you decide to sell the radio someday.
I began the search for a quite fan. None filled the bill. Even the
smallest ones were quite audible. I tried putting a resistor in series
with a few of them. Running a 12vdc fan at 6vdc really made them quite
but they were reluctant to start up at that voltage.
I stumbled upon a junked out Hewlett Packard laser printer at work which
had a 24vdc fan. Applying 12vdc, I was amazed how well it started up and
how quite it was. I removed the aluminum bracket from the Omni-6,
removed the little speaker (which I never used anyway), broke off the
studs, drilled a couple of holes and mounted the fan in the speaker
hole. 12v was easily obtained from the final's power lead. The air
exhaust through the speaker grill. The fan was virtually inaudible and
just a faint whisp of air emmits from the speaker grill. Inside, the rig
stayed perfectly cool even under the heavist operation. BFO drift was
eliminated.
I ordered a replacement bracket from TT just in case.....
N4LQ STEVE
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