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<DIV>In a message dated 23/04/2013 15:32:56 GMT Standard Time, kd2e@comcast.net
writes:</DIV>
<BLOCKQUOTE
style="BORDER-LEFT: blue 2px solid; PADDING-LEFT: 5px; MARGIN-LEFT: 5px"><FONT
style="BACKGROUND-COLOR: transparent" color=#000000 size=2 face=Arial>Some of
the old Heathkit HP23's had a toggle switch on it to switch bias voltage.
...Not sure if it was the 23 or 23A.<BR>Newer ones did not, and had to be hard
wired. <BR>Just make sure you have the right setting for your
rig.<BR></FONT></BLOCKQUOTE></DIV>
<DIV></DIV></DIV>
<DIV>===========================================</DIV>
<DIV>Hi All</DIV>
<DIV> </DIV>
<DIV>The HP23a and 23b had the toggle switch to select +250 or +300v, the HP23
and 23c only had hardwired links.</DIV>
<DIV> </DIV>
<DIV>The HP23 and 23a had a presettable negative bias on pin 11 of the PSU
connector, the HP23b and 23c did not. On all four the fixed negative bias
appeared on pin 1.</DIV>
<DIV> </DIV>
<DIV><FONT lang=0 size=2 face=Arial FAMILY="SANSSERIF"
PTSIZE="10">73<BR></FONT><FONT lang=0 color=#0000ff size=4 face=Arial
FAMILY="SANSSERIF" PTSIZE="14"><I><BR>Bob</FONT><FONT lang=0 color=#000000
size=2 face=Arial FAMILY="SANSSERIF" PTSIZE="10"></I><BR>Bob F Burns G3OOU<BR>C
Eng, FIET, MSE<BR>G-QRP 6907<BR>Secretary of Crystal Palace Radio &
Electronics Club: www.g3oou.co.uk<BR>Technical web site:
www.qsl.net/g3oou<BR>@BobFBurns on Twitter:
http://twitter.com/BobFBurns</FONT></DIV></FONT></BODY></HTML>