<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META content="text/html; charset=US-ASCII" http-equiv=Content-Type>
<META name=GENERATOR content="MSHTML 9.00.8112.16437"></HEAD>
<BODY style="FONT-FAMILY: Arial; COLOR: #000000; FONT-SIZE: 10pt" id=role_body
bottomMargin=7 leftMargin=7 rightMargin=7 topMargin=7><FONT id=role_document
color=#000000 size=2 face=Arial>
<DIV>Hi Dick</DIV>
<DIV> </DIV>
<DIV>Are you measuring/assessing the vertical sensitivity using a signal
generator or a rig?</DIV>
<DIV> </DIV>
<DIV>The resonant frequency of the tuned circuit using inductor L1 is
dependant on the capacitance of the coax cable connecting the SB610 to the rig
plus any coax inside that rig and the small coupling capacitor to the receiver
last IF amplifier. If I recall correctly Heathkit recommended the use of high
impedance (93ohms) cable because it has a lower capacitance per unit
length than conventional 50 ohm type. You need to get that tuned circuit to
show resonance at the correct frequency in order to get the correct
sensitivity.</DIV>
<DIV> </DIV>
<DIV>Check the resonance with a GDO to see where it is currently located.</DIV>
<DIV> </DIV>
<DIV>If you connect a signal generator to the vertical input the resonance of L1
will not be apparent because of loading by the generator output impedance,
typically 50 ohms.</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<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
href="http://www.g3oou.co.uk/">www.g3oou.co.uk</A><BR>Technical web site: <A
href="http://www.qsl.net/g3oou">www.qsl.net/g3oou</A></FONT></DIV></FONT></BODY></HTML>