[ARC5] Way OT -- SX-28

[radio_man at wbsnet.org]

I stand corrected.  My Select-0-Ject is metal stamped SAF-1, however
holding it correct in light there is an ink stamp of SOJ-2 over the top of
it.  Wonder why the two nomenclatures?

Rod
K0EQH



> I have a National SAF-1-2 Select-O-Ject, it was hooked to an SX-28 which
I
> sold a while back. Yes it connected to the audio chain. The National
also
> has a terminal to connect a key so you can use it as a code practice
oscillator I also have a Heathkit QF-1 Q-multiplier, it does not hook to
the audio circuit, rather connects to the 455Kcs (Khz) IF at the mixer.
Rod
> K0EQH
>>     Q-Multipliers work at audio. While they can be of
>> considerable help they do not eliminate beat images (the beat at the
other side of a CW signal) or specific QRM, i.e. a single
>> signal, like another station adjacent to the one you want. They really
do not improve the selectivity.
>>     The original Q-Multiplier was designed by a fellow at
>> Stanford U. I am unable to remember his name. The circuit and
>> theory was published in QST and a commercial version was made by
National under the name Select-O-Ject. Heathkit also made a
>> version. They operated at audio frequencies so could be used on any
receiver and did help with very low cost receivers with
>> minimal selectivity.
>>     Of course, the principle works at RF too and some receivers
>> were built with RF selector or notch filters. These, like a
>> crystal filter, do null out a specific signal and will eliminate CW
images but the fact that a  Q-multiplier could be used without any
modification to the receiver made them very popular.
>> On 8/6/2021 12:50 PM, Hubert Miller wrote:
>>> You folk remember that ARRL article on the Q-multiplier outboard unit for
>>> the SX-28 ? It was published, I think, in some edition of the Handbook or
>>> maybe in QST. Would that addition be for more variable SSB selectivity
or the notch feature, or actually both ?
>>> -Hue Miller
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>> --
>> Richard Knoppow
>> 1oldlens1 at ix.netcom.com
>> WB6KBL
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