[Amps] QRO Heat management

[Pat Barthelow]

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 at k6bj.org 
Jamesburg Moon Bounce Team

http://www.jamesburgdish.org


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