[TenTec] Fw: Cooling fans and IF gain

[Steve Baron - KB3MM]

Interesting.

I got the TT 963 supply with my Orion.  I was surprised the first time its
fan turned on.  Just sitting on the desk with the Orion in RCV, the fan will
run once in a while.

----- Original Message ----- 
From: "Mike Coogan W7MGC" <mikegc at pacifier.com>
To: <tentec at contesting.com>
Sent: Friday, July 15, 2005 18:09
Subject: [TenTec] Fw: Cooling fans and IF gain


> I noticed the same heat build up on the 962 p.s. for my Omni 6+ when
> running Rtty. I mounted a TT 310 fan on the heat sink of the power
> supply, powered from the 12v dc outlet on the p.s.
>
>  Mike  W7MGC
> Vancouver, Washington
>
> Omni 6+ >>253 Auto Tuner>>HercII amp, Love it!
>
>
> ----- Original Message ----- 
> From: "Robert & Linda McGraw K4TAX" <RMcGraw at Blomand.Net>
> To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
> Sent: Friday, July 15, 2005 6:08 AM
> Subject: Re: [TenTec] Cooling fans and IF gain
>
>
> > Interestingly enough, the Omni VI+ PA is rated at 100% duty cycle
> > while the
> > 961 power supply is not.  I've found that additional cooling on the
> > power
> > supply is necessary in high duty cycle modes, partly caused by the
> > bridge
> > rectifier being mounted to the bottom plate for heat dissipation.  A
> > small
> > 12V fan blowing on the heat sink in the rear takes care of the
> > problem.
> > Also, one might take note that if the power supply is sitting flat on
> > the
> > desk there is little room at the bottom rear for vertical air
> > convection.
> > If possible, elevate the power supply, allow the heat sink to hang off
> > of
> > the rear support and allow the heat sink to have more "breathing
> > room".
> >
> > As to the Omni VI+, I've found that heat build up within the radio
> > does
> > cause some frequency drift primarily due to BFO frequency changes.  I
> > changed my BFO's to TXCO's and found a nice improvement.  All in all,
> > probably not worth the investment, time and effort, for such a small
> > benefit.
> >
> > I've read cases where one removed the speaker, replaced it with a
> > computer
> > type 12 V fan that made improvements of about the same magnitude to
> > the
> > radio. This would be a lot less work and a lot less $$.
> >
> > 73
> > Bob, K4TAX
> >
> >
> > ----- Original Message ----- 
> > From: "Chuck Guenther" <ni0c at earthlink.net>
> > To: <tentec at contesting.com>
> > Sent: Thursday, July 14, 2005 8:17 PM
> > Subject: [TenTec] Cooling fans and IF gain
> >
> >
> >> N6KB wrote: "I find that operating my Omni VI in CW contests a fan on
> >> the
> >> PA heat
> >> sink is necessary. My Kenwood TS-440 has a built-in fan with
> >> temperature
> >> controlled speed, or at least duty cycle. The TS-440 receiver
> >> performance in contest conditions does not compare to the Omni VI
> >> though. I wish Ten-Tec would have included a built in fan. I have
> >> never
> >> tried, or thought that I needed, a fan to ventilate the insides of
> >> the
> >> Omni VI though."
> >>
> >> I used a TS-440S for about seven years (in fact I still have it).
> >> The
> >> only time the cooling fan ever came on was during an RTTY contest (I
> >> was
> >> running about 60 watts).  It never came on when operating CW or SSB.
> >>
> >> With the Ten Tec rig, I find the heat sink of my 961 PS always runs
> >> at a
> >> higher temperature than the Omni 6 PA heat sink.
> >>
> >> Today, in order to alleviate my gain problem, I swapped out the Ten
> >> Tec
> >> 221 filter for the INRAD 753 (which has a few dB less insertion
> >> loss).
> >> The gain seems adequate (and more stable) now, so perhaps my problem
> >> was
> >> in the filter, or the connections thereto.
> >>
> >> 73,
> >> Chuck  NI0C
> >> .
> >> _______________________________________________
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> >> TenTec at contesting.com
> >> http://lists.contesting.com/mailman/listinfo/tentec
> >>
> >
> >
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