>Over the weekend I had an opportunity to work on a Henry 2K Classic. This
>is a beautiful 120 pound console amplifier using 2 x 3-500Z tubes.
>
>After repairing some problems and getting it working, I measured the
>filament voltage at the socket. It was 5.62 volts with 252 vac line
>voltage. I noted that there was a special "surge" inductor under the
>chassis for the filament already. Filament volts at the transformer was
>12.05 volts - feeding the 2 tubes filaments in series. I reduced the
>voltage by installing 2 x .1 ohm 10 watt resistors in parallel at the
>transformer.
>
>After all work was done, 70 watts drive produced 1,000 watts out on high
>power - which is exactly the same power I measured 2 days earlier on the
>55 pound (or so) Heath SB-220 on high power with the same drive.
>
>The Henry is a beautiful amplifier that uses no variable plate tuning
>capacitor. Instead, it uses fixed, switched capacitors and tunes with a
>variable inductor. Although it is very nice, it is probably the slowest
>amp to QSY of any commercial amp I have ever used and would be a horrible
>contest amp. It may even be slower than my home brew 4-1000 amplifiers.
>
>Looking at the construction of both the Henry and the Heath, I am
>impressed that the "puny" Heath puts out as much power as the Henry. It
>is a tribute to the design skills of the Heath engineers.
>
Amen. The SB-220 is a winner - provided: the fan motor is oiled every
couple of years, it gets the high speed switching mod, glitch protection,
and lower VHF Q suppressors.
later, Colin
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
--
FAQ on WWW: http://www.contesting.com/FAQ/amps
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
|