[AMRadio] Lowest level modulation


Jim candela jcandela at prodigy.net
Wed Dec 22 21:17:24 EST 2004


Steve,

What about some of us AM'ers that have a sub-audible frequency shift with
modulation due to poor power supply regulation, and decoupling? This is
pretty common with some of our "cherished" vintage equipment. It does have a
beneficial effect though in that it when strong discourages a SSB station
from trying to zero beat. The famous BC-375 with a MO-PA arrangement had
some audio rate FM as did the BC-223 that I once had (801 osc + 801 PA
modulated with PP 46's). I believe "Timtron" Wa1HLR once had a BC-375 that
he used as the "SBE rig". SBE stood for "side band eliminator". I had dinner
once with Tim 20+ years ago where he described a TPTG 450th oscillator on 75
meters AM, FM, PM, or just "all modulation". He said it sure cleared out the
frequency, and sounded great on a wide band AM receiver.. These examples may
be illegal, but...

Regards,
Jim
WD5JKO

-----Original Message-----
From: amradio-bounces at mailman.qth.net
[mailto:amradio-bounces at mailman.qth.net]On Behalf Of Mike Dorworth, K4XM
Sent: Wednesday, December 22, 2004 8:01 PM
To: Discussion of AM Radio
Subject: Re: [AMRadio] Lowest level modulation


Hi , it is illegal to use a modulated oscillator below about 2 meters. It
will work but adds FM even to a crystal oscillator. In fact commercial vhf
equipment using crystals actually phase modulate the crystal oscillator to
get FM. They of course go through several multiplications to get the plus
and minus 5 kc deviation.. That's kHz for youngsters!.. The rules simply
state NO!..hope this helps.. Mike K4XM
----- Original Message -----
From: <StephenTetorka at cs.com>
To: <amradio at mailman.qth.net>
Sent: Wednesday, December 22, 2004 8:51 PM
Subject: [AMRadio] Lowest level modulation


> Hi All:
>
> As I understand it, low level modulation is anything prior to the amp.
>
> Therefore, is it possible to modulate the grid oscillator RF input
signal -
> crystal or otherwise - and expect an AM output?
>
> Next question: how?
>
> Regards,
> Steve
> WA2TAK
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