----- Original Message -----
From: "Steve Wedge" <[email protected]>
To: <[email protected]>
Cc: <[email protected]>
Sent: Monday, October 10, 2011 6:28 AM
Subject: [Drakelist] TR-4C filament Voltage
Hi, Bob -
I wouldn't worry much about the 230 vs 240 V difference.
Back when the Drakes were made, most line voltage in the
US were assumed to be 115 VAC anyway. Since 115 is half
230 you should be spot-on. (I suspect the higher voltages
we now have in the US may slightly contribute to the
transformers running warmer).
I can't recall if you folks in N.Z. use 50 or 60 Hz. I
found during my time working on power supplies years ago
that this difference would have more of an effect on the
equipment (it causes transformers rated for 60 Hz to run
much warmer at 50 Hz) than a change in line voltage
(within reason). I can also recall testing lots of
equipment that was designed to run at least +/- 10% of
rated line voltage. Tube equipment, in general, tends to
be less fussy.
I'd try firing it up with what you have and measuring your
power out.
73,
Steve, W1ES/4
The reduced filament voltage may not be a problem. I am
not sure about indirectly heated tubes but for tungsten or
thoriated tungsten filaments a 5% reduction in voltage
(about what Bob is reporting) will increase life by nearly
double with little reduction in emission. Indirectly heated
filaments may be more critical.
50hz power will cause increased heating due to core
losses but the transformers in much Drake stuff run hot
anyway, a small fan may help with this.
--
Richard Knoppow
Los Angeles
WB6KBL
[email protected]
_______________________________________________
Drakelist mailing list
[email protected]
http://mailman.zerobeat.net/mailman/listinfo/drakelist
