thanks Evan..
I was kinda of wondering how drake did the fan control...
the L7 uses a blower or fan?
Mike, WB8VGE
SunLight Energy Systems
The Heathkit Shop
http://www.theheathkitshop.com/
J e e p
o|||||||o
Note: No trees were killed in the sending of this message, but a
large number of electrons were terribly inconvenienced
On Dec 27, 2007, at 1:53 PM, [EMAIL PROTECTED] wrote:
Mike,
The L4B uses a constant speed blower. In contrast, the L7 uses a
"two speed fan" that accomplishes this task by using a resistor in
series with the fan. When the exhaust temperature exceeds the value
on the thermostat, it shorts out the resistor, and the fan goes into
high speed (i.e. normal, full 110 vac voltage to the fan). It will
stay in this condition until the temperature drops accordingly.
Good luck with the Dentron and thanks for sharing your experiences.
Happy New Year and 73s,
Evan
-----Original Message-----
From: Mike Bryce <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED]
Sent: Thu, 27 Dec 2007 1:31 pm
Subject: [drakelist] Soft key and fan controller for HF amplifiers
Boys...and girls...
I have been working on a old dentron clipperton L amplifier...
after much research and email chatting,I have it up and running.
Designed a new power supply pcb for it and it seems to work like it
should..
One of the things I was told was the clipperton L is a really solid
1Kw amp and a so so 2Kw amp
one thing that get's it goat is that is over heats..
The unit I have has a 390 ohm resistor in series with the ac supply
feeding the fan motor.
Shorting out the resistors puts the fan in high gear. it also makes
it a lot louder
So... a simple fix
here's what I did
Added a softkey that is optically coupled to the radio. Instead of
switching 25 volts at 250 ma, the radio only sees 12 volts at 10 ma.
The amp is keyed by a high power MOSFET or you can select relay
output keying (works with any amp that way)
then I added a fan controller
when you key the amp, nothing happens but keep the amp keyed a minute
or two and the fan kicks up to high speed.
after you unkey, the fan will run on high for a while and then drop
back to low speed
the amount of time will depend on how long you talk!
the longer you key down, the longer the fan will run in high speed
I don't know if the drake amps use any sort of resistor in the fan
lead or not.
but... you can always add an extra fan or add a fan to the back of
the TRXX series rigs..
it was a fun project
anyone interested let me know
mike
Mike, WB8VGE
SunLight Energy Systems
The Heathkit Shop
http://www.theheathkitshop.com/
J e e p
o|||||||o
Note: No trees were killed in the sending of this message, but a
large number of electrons were terribly inconvenienced
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