<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:times new roman,new york,times,serif;font-size:12pt"><div>Bob,<br><br>Greatly enjoyed your attention to detail and good engineering sense! Keep us up to date!<br><br>Bob Groh, WA2CKY<br>'old timer and radio designer'<br></div><div style="font-family:times new roman, new york, times, serif;font-size:12pt"><br><div style="font-family:times new roman, new york, times, serif;font-size:12pt"><font size="2" face="Tahoma"><hr size="1"><b><span style="font-weight: bold;">From:</span></b> "G3OOU@aol.com" <G3OOU@aol.com><br><b><span style="font-weight: bold;">To:</span></b> kgordon2006@frontier.com; heath@puck.nether.net<br><b><span style="font-weight: bold;">Sent:</span></b> Tue, January 17, 2012 4:09:22 PM<br><b><span style="font-weight: bold;">Subject:</span></b> [Heath] SB-101 Remaining Issues<br></font><br>
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<div>Hi Ken</div>
<div> </div>
<div>I have looked through all of my SB-101 related documents and in the end I
have followed what was done in the SB-102 in relation to V3 dissipation by
changing the screen feed from 22K to 33K. This brings the overall dissipation
(anode and screen) in the valve down to 3.2W and still allows the S meter zero
to function correctly with the SB-101 resistor values although I have changed
the zero pot for a spare as the old track was unreliable.</div>
<div> </div>
<div>The overall sensitivity on 7MHz is 12dB S/N for 0.5uV at 1KHz audio signal
with a 6HS6 in the RF stage and a 6AH6 in the mixer position to maintain the
heater balance as you suggested. The measured dissipations for both the new Rx
RF and mixer stages are well within the valve specs so no component changes
needed. Yet to do a full realignment of the band circuits with the new valves so
may gain a little more.</div>
<div> </div>
<div>I have a 5dB peak in the Rx HF end of the passband which I have yet to
resolve, although I did replace the 2K filter matching resistors as the old ones
were nearly 3K so this could be a crystal filter problem or something wrong in
the audio system.</div>
<div> </div>
<div>I would like to lower the heat generated by the audio output stage a bit
but still thinking that one through. Tx seems OK so far.</div>
<div> </div>
<div>Getting there slowly.</div>
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<div><font family="SANSSERIF" size="2" face="Arial">73<br></font><font family="SANSSERIF" size="4" color="#0000ff" face="Arial"><i><br>Bob</i></font><i><font family="SANSSERIF" size="2" color="#000000" face="Arial"></font></i><font family="SANSSERIF" size="2" color="#000000" face="Arial"><br>Bob F Burns<br>C Eng,
FIET, MSE<br>Amateur Radio Callsign: G3OOU<br>Registered RSGB
Instructor<br>G-QRP Member No: 6907; Zone: 14, QRA: IO91WH; WAB:
TQ25<br>Secretary of Crystal Palace Radio & Electronics Club: <a rel="nofollow" target="_blank" href="http://www.g3oou.co.uk/">www.g3oou.co.uk</a><br>Technical web site: <a rel="nofollow" target="_blank" href="http://www.qsl.net/g3oou">www.qsl.net/g3oou</a></font></div></font></div></div>
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