Curt -
The 4 Line receivers have Ground - 6V - 12V. So one 12V line is grounded. The R-4C has only 6 VAC
filaments.
The transmitters and TR-(any) have only a single 12 VAC filament supply. Be careful where you get
the voltage here, as there are several series string arrangements to power 6 VAC tubes.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
<www.k4oah.com>
Curt wrote:
BE VERY CAREFUL....In many (most?) of the 4 line, the 12V filament circuit has its center tap
grounded so the 6v filaments work from each half of the 12V winding to ground.
If you ground either side of the 12V line to the RCA jack, you short out half of the 12V...with
luck, you blow the filament fuse..no luck and you smoke something else. If you use the 12V
filaments to run a rectifier ( I use a bridge device) DO NOT ground either side of the DC output,
FYI
Curt
KU8L
On 1/8/2012 7:45 PM, Steve Wedge wrote:
I've done all which-ways.
I once used a 120V fan and used a big, honkin' wire-wound resistor to slow it
down.
I currently use a 12V fan with a thermistor over my finals, running off a 12V wall wart. the fan
runs really slow until the temp gets to the point where the thermistor lets it go for full-speed.
This fan cost me $5 at a hamfest.
I've worked on a couple of R-4B's where the previous owner tapped off the filament supply with a
diode and cap (half-wave rectifier). The fans he used are a little louder than my Xmitter fan.
If you opt for using on-board power, you can tap off the filament supply for 12V and feed it to
an RCA jack in the SPARE location, or just feed wires through that hole. I like just setting the
fan on top, using rubber feet. No holes get drilled that way...
YMMV,
Steve Wedge, W1ES/4
Live free or die: Death is not the worst of evils.
John Stark.
All my computers have my signature with various pearls of wisdom appended
thereto.
*From:* Michael & Sue Trussell <mailto:mtruss8...@comcast.net>
*Sent:* Saturday, January 07, 2012 5:33 PM
*To:* drakelist@zerobeat.net <mailto:drakelist@zerobeat.net>
*Subject:* [Drakelist] Need a fan for my T-4XC Transmitter?
I need to replace my old 30 year old 110 volt fan on my transmitter. I know a few of you have
used the twelve 12 volt fans and some have used the 110 volt version. What I would like to know
where I can get power so I don’t have to plug the fan in every time I turn the rig on. I would
like the fan to come on when I turn on the power to the transmitter, any suggestions?
Thank you in advance
Michael J Trussell KA8ASN
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