----- Original Message -----
From: "Garey Barrell" <[email protected]>
To: <[email protected]>
Sent: Sunday, January 15, 2012 1:27 PM
Subject: Re: [Drakelist] AC-4 Voltages
Mark -
Interesting. A primary voltage of 121.5 VAC resulted in
measured AC voltages out of the transformer at 266 VAC,
108 and 98. The filament measured 14 VAC, all no load.
266 x 2.828 = 752 V peak
108 x 2.828 = 305 V peak
Both have very high bleeders, a mA or two so will reach
near these peak voltages at no load.
98 x 28.28 = 138 V peak. The divider on the output is
nominally 69 VDC at mid-range with NO load. The
transmitter is specified as a 33k ohm load.
All measurements taken with a calibrated Fluke DMM.
73, Garey - K4OAH
Glen Allen, VA
I remeasured both supplies. Unloaded and with line
voltage at about 120VAC, I get
HV= +702 VDC on both. Only measured medium voltage on one
and filament on one.
MV= +287VDC
Filament= 13.8 VAC
Didn't remeasure the bias.
Meter: Tektronix DMM 254
These were all measured at the end of the power plug with a
jumper across the line switch contacts. I actually opened up
a supply to measure the first voltages. Not sure where the
difference came from.
FWIW, wire doesn't work well to short the plug, I used
bits of cut-off paper clip and that worked fine.
It appears that the original poster's voltages are fine
although I still think the filament is high. Since that is a
matter of the turns ratio of the transformer it may still be
a measurement error. The voltages that count are those
measured with the transmitter working.
--
Richard Knoppow
Los Angeles
WB6KBL
[email protected]
_______________________________________________
Drakelist mailing list
[email protected]
http://mailman.zerobeat.net/mailman/listinfo/drakelist
