Pat I cant speak to the latest and greatest overpriced stuff that has
very little value added, to me anyway, over something 20-30 years old.
Ive been using external muffin fans since the first computer surplus hit
the streets in the early 70's and still use them on amps and even xcvrs
under high duty cycles.
Commercial rigs from the 50's like the HT-32 and CE 100V had fans built
in.
With the little PC fans from my local old PC parts dealer I adapt them
into test equipment, my Viking I, and lots of old hot running antique
radios which I collect and restore. A very small amount of air movement
does wonders.
With respect to vinatge tube gear I also use a 12-13V bucking xfmr to
bring the AC down to around 110V which helps considerably. Each work and
operating bench is fed with a suitably sized transformer to an outlet
strip. Upstairs Ive either added them into consoles or other radios that
have the room underneath or mount them in a small outlet box. Since a 2A
xfmr can handle a 200W+ piece of equipment it isnt expensive nor does it
take up much space.
Carl
KM1H
----- Original Message -----
From: "Pat Barthelow" <aa6eg@hotmail.com>
To: <amps@contesting.com>
Sent: Sunday, November 09, 2008 12:16 PM
Subject: [Amps] QRO Heat management
>
>
>
>
> Common to many discussions, about reliability and life of Ham
> amplifiers and power supplies,
> include an aspect where an effort is made to economize and "push"
> limits of components in hopes of
> money or space savings. I started in 1968, with a Drake TR-3 with the
> 3 ea of the tiny 12JB6 sweep tube
> finals, ( about $4.00 ea, $12 BUCKS a set!) and as a kid who liked CW,
> was cautioned about the low duty cycle, and plate dissapation of those
> tubes.
> I longed for a "sturdy" 6146W radio. TX. I remember also as a kid,
> my stockinged feed sitting on the drake
> Power supply transformer, sitting under the ops table, and noticed how
> HOT things got when operating. In more modern times I noticed my
> Drake L-4B also got Very hot both the RF Deck, and the power supply,
> esp in contest mode, so I used to, and still do, hang some muffin
> fans at strategic locations on P/S and Rf decks, to cool them down.
> I also remember my library of Eimac Amp Notes, by Bill Orr, W6SAI, a
> statement that, the only time you have added too much blower capacity
> or flow, is if a tube is pushed out of its socket.... Mo' is better,
> until that point.
> Nowadays, there are a lot of mini fans that might even be locatable
> inside cabinets that could move air around to dissapate heat.
> Back in the 60s; pre PC era, muffin fans were EXPENSIVE, (for a kid)
> something like $25, (1968 Dollars) Now they are all over the place,
> surplus pulls out of computers, etc. So.. the question is, will
> judicious use of external muffin fans really do much to increase life
> of amateur radio QRO amp components, like capacitors, resistors,
> diodes, and transfomers? ( or even modern Transceiver SS PA's?)
>
> Or, do the engineers who designed the gear actually determine and
> build good heat management schemes, without the need for outside
> cooling help?
>
>
>
>
>
> All the best, Pat Barthelow aa6eg@k6bj.org
> Jamesburg Moon Bounce Team
>
> http://www.jamesburgdish.org
>
>
> "The most exciting phrase to hear in science,
>
> the one that heralds new discoveries, is not
>
> "Eureka!" (I found it!) but...
>
>
> "That's
> funny..."" --Isaac Asimov
>
>
>
>
>
>
>
>
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
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