>
>OK, I'm new to using HF amplifiers. Here's some rudimentary questions for
>everyone. I just bought a Henry 2K-4. It has 2 3-500Z's inside and the blower
>makes a fine noise. Not noisier than we have a right to expect but noisy none
>the less.
>
>My inclination is to use the amp when I can't make the contact otherwise.
>That's what the rules say and I'm fine with that. I'll leave it off 90% of
>the time and turn it on when I need it.
>
>1) The Henry manual doesn't say how long to leave the amp on before transmit.
>Some places I've read that directly heated cathode tubes are ready to load
>after 3-5 seconds. Is that reasonable for this amp? What is?
>
One second is plenty. The 3-500Z/8008 can not be damaged by insufficient
warm up.
>2) After I've been running the limit in an SSB QSO what's the recommended
>cool>down period before I shut the power off?
>
My guess is c. ten-seconds cooldown for unprocessed SSB and 30-seconds
for RTTY. .
>3) For those of you who run 3-500Z amps, do you turn the amp on and off
>frequently when operating at one sitting? I'd be concerned about thermal
>shock to the filaments shorting the tube life if I made a habit of this. But
is
>sure is noisy...
A step-start would be in order.
>
>4) Would a blower control relay that started the blower on transmit and
>turned the blower off (or down) after the cool down period work. Is there
some
>reason to have the blower on when there is no current through the tubes to
heat
>things up?
The approx. 73w of heat from the filament current will melt the solder
out of pins 1 and 5 unless cooling air is present.
> That would allow me to not cycle the filaments just for the sake of
>getting the noise level down. I could even set up this blower control circuit
to run
>the blower the cool down period after I turn the power switch off.
3-500Z amplifiers with superior cooling to the Henrys are the TL-922 and
the SB-220. The 220 is definitely the quietest. ''Air system'' sockets
cause the tubes to operate at elevated temps.
>
cheers, Bill
- 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
|