Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Keith -
Good point. Couple of points.
1. In over 40 years of owning, using and working on _lots_ of Drake
gear, I have never seen a failed AC-3/4 transformer. I'm sure there
have been some, there were probably some with manufacturing defects.
They "do" thump if you happen to close the switch on or near the peak of
the AC waveform, but it doesn't seem to hurt anything.
2. What usually kills power switches is the "arc" that forms when the
switch is turned off from the inductive kick of the transformer
winding. Second is the "growth" of a small bump on either of the
contacts that "makes" first when closed, which forces all the current
through that bump before the rest of the contacts touch. "Good"
contacts, closed, are pretty tough!
The Sigtomics units look nice, and not ridiculously priced. The
thermistor components are readily available, and can be installed
directly in vintage receivers for a lot less money. They aren't as
useful in transmitters because of the large difference in turn-on and
full power transmit power requirements. You pretty well have to have a
relay to short out whatever resistance you put in-line at turn on. The
first thing I did to my L-4B when I got it 30 years ago was to put a
time delay relay and power resistor. The amp still has the original
tubes and original pilot lamps.
Anyway, there is certainly nothing wrong with using the Sigtomics units,
but I'm not sure they will really improve the reliability of the
equipment significantly over an external power control.
73, Garey - K4OAH
Atlanta
Drake C-Line Service Manual
<http://www.k4oah.com>
Keith Hamilton wrote:
Has anyone tried the soft-start current limiting boxes sold by
Sigtomics (http://sigtomics.com)? Would that help prolong the life of
the on-off switch as well as the transformer? My AC-4 really
"thumps" when I turn my T-X4C transmitter on. Seems a better solution
than a cheap computer power strip. Or not?
Keith Hamilton, N8QO
[EMAIL PROTECTED]
On Jan 19, 2006, at 8:43 AM, [EMAIL PROTECTED] wrote:
On Wed, 18 Jan 2006, Garey Barrell wrote:
With the scarcity of power switches for vintage gear, I always leave
mine switched on and control power with an inexpensive computer power
strip.
Agreed - plus I have an inrush limiting box in series to avoid thumpin'
the R-4* on power-up.
I found some power strips at IKEA that have only 3 outlets (instead
of the
typical 6 plugs) which are nice and small. It's the only thing i've
found
of use at IKEA but don't tell my wife that. hi
--
73 Jason N1SU
http://n1su.com/
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