[Hallicrafters] HY37 HV and bias voltages

[David C. Hallam]

The higher plate voltage is no problem.  Check the screen voltage on the
6146's.  It should be close to the specified value with allowances for the
possibility of higher AC line voltage.  I replaced the 5V4 in mine with no
change in the low voltage.

Raising the plate voltage has little or no effect on zero signal plate
current.  However plate current it is greatly affected by changes in screen
voltage.  You should adjust the bias back to the recommended voltage by the
procedure in the manual.

David C. Hallam
KC2JD

-----Original Message-----
From: hallicrafters-bounces at mailman.qth.net
[mailto:hallicrafters-bounces at mailman.qth.net]On Behalf Of Joseph
Trombino Jr
Sent: Thursday, August 04, 2005 2:36 PM
To: Hallicrafters
Subject: [Hallicrafters] HY37 HV and bias voltages


I just replaced the electrolytic caps in my HT37 and added the Weber Copper
Top solid state rectifiers to replace the 5R4 and 5V4 tubes.

My HV now reads +907 VDC and the bias is -65VDC.

(I didn't do any measurements before the replacement job since I didn't want
to take a chance with a bad cap and blow the power transformer)

Believe I can try and adjust the bias voltage down to the recommended -49
but am wondering if the higher HV is OK.

Wonder if the solid state rectifiers are the reason for the higher
HV.....the book indicates that the HV should be +750.

Ideas comments are welcomed.

                                   73, Joe W2KJ
                                   Trying to get a vintage station on the
air


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