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"Boat Anchor" & Classic Equipment

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Hollow State Heterodyne Type Transmitting VFOs

Posted: 08 Mar 2017 07:13 AM PST
http://forums.qrz.com/index.php?thre...g-vfos.558204/

In another forum, mention was made of a tube-type transmitting VFO that
would use the heterodyne method (a tunable VFO mixed with a crystal
oscillator to provide output on one or more amateur bands). Rather than
disrupt that thread, Ive started this one.



Such VFOs dont appear much in the amateur handbooks and magazines of the
hollow-state era, because of the complexity and some of the pitfalls of
such VFOs. But there were some articles, and some info out there, which I
will list in a...



Hollow State Heterodyne Type Transmitting VFOs

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The mysterious "100K ohm" resistor

Posted: 07 Mar 2017 05:56 PM PST
http://forums.qrz.com/index.php?thre...sistor.558178/

Just last night, I ran into a 100K ohm resistor in a Heath SB-101 that was
reading 0.0 ohms on my DMM! The resistor was original and was not
discolored, etc.



This particular SB-101 had been passed down from several persons none of
whom could get the unit to operate properly. I strongly suspect a
manufacturing defect when the resistor was made and it got past QA.



The resistor was in the microphone amplifier stage and there was no audio
getting out of the stage because...



The mysterious "100K ohm" resistor

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SB-100 - Low ALC/transmit with mic gain fully CW

Posted: 07 Mar 2017 05:44 PM PST
http://forums.qrz.com/index.php?thre...lly-cw.558164/

So I finally have a hi-impedance microphone(a Shure 450 Series ii, with the
hi/lo impedance switch) that I purchased off of eBay in my possession
temporarily rigged up to the radio(wires are all jumpered, nothing soldered
yet with that expensive 2-pin connector.), and while it does appear to
work, to get any kind of meter deflection, I feel like Im darn near
screaming into the thing with the mic gain fully clockwise to get any kind
of alc on the radio or output on my watt meter.. wondering...



SB-100 - Low ALC/transmit with mic gain fully CW