Rich Measures wrote:
>>I'm seriously considering silver soldering the taps on the tank coil -
>>that's with solder melting at redheat, not the lower melting point stuff for
>>ordinary soldering irons.
>? If one is using a pressurized chassis, by drilling a grid of small
>holes in the chassis underneath L1, an updraft is created which cools the
>coil. Thus, one can use 6% Ag, 94% Sn solder (eutectic 221 degrees C).
>This material is approx. 4 times stronger than Ag/Pb solder, and is more
>conductive too. // Apparently, Heath had things figured out pretty well
>by putting cooling air on the SB-220 tank and bandswitch.
Well, there's always the old VHF/UHF trick of pressurizing the whole
output compartment. Cold air circulates all around the tank circuit and
the lower part of the tube, and then flows out through the anode cooler
via a sealed exit chimney.
A smaller, controlled bleed of cold air flows downwards over the base.
Because the air-flows to the anode and to the base are in parallel (not
in series as usual) the back-pressure is lower and therefore the blower
produces a higher volume flow rate.
73 from Ian G3SEK Editor, 'The VHF/UHF DX Book'
'In Practice' columnist for RadCom (RSGB)
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