[ARC5] Can yoiu say...

[K5MYJ]

In the 50's and 60's there were two primary causes of TVI.

One was that TV receivers of that period had 21MHz IFs. 80M and 40M 
multiplied directly to 21MHz. Then there was 15M. Straight in!

The other was TV receiver overload. A lot of people just used "Rabbit Ears". 
And real roof mounted antennas were not a whole lot better.

I could (DID) jam my own TV set with nothing more than my grid dip meter!

Bob Macklin
K5MYJ
Seattle, Wa.
"Real Radios Glow In The Dark"
----- Original Message ----- 
From: "David Stinson" <arc5 at ix.netcom.com>
To: <Arc5 at mailman.qth.net>
Sent: Tuesday, June 13, 2017 11:49 AM
Subject: Re: [ARC5] Can yoiu say...


> >... You have to read the book on modifying Command Sets to understand the 
> >reasons for modifying them. AND THEY WERE GREAT TVI GENERATORS! Bob 
> >Macklin
>
> Respectfully:
> Those ideas were/are repeated endlessly, friend to friend and magazine to 
> magazine.
> And they are myths.  Myths.
> Examples of exactly what I've been saying.
>
> The only "understandings" in the Surplus
> Conversion Manuls were mis-understandings.
> They addressed "problems" that were of their
> own making and created "solutions" that produced
> even more problems. The "copper shielding for TVI"
> is one such thing.  Utterly needless destruction and
> trouble for something cured by a single capacitor
> and few moment's reflection.  But "common knowledge"
> becomes "fact" and then it's almost immovable.
>
> For instance:  The only reason TVI was a problem
> with Command Set transmitters is because they were loaded and fed 
> improperly to common "ham" antennas- which defeated their excellent 
> harmonic isolation.   I'm not just talking through my hat; I put
> them on modern spectrum display equipment years ago
> and investigated several feeding options, including the
> typical ham "just stick the coax/twinlead on it and go."
>
> When properly matched to a 50 Ohm coaxial line
> and a 50-Ohm load through a simple series capacitor,
> the rigs were as clean as any modern transceiver.  There were NO spurious 
> products anywhere near VHF.
> The equipment I used had a noise floor of, IIRC, better than -95 dBm and 
> with the rig fed directly to its internal dummy load, nothing in  the TV 
> ranges.  Zip. And the 2nd, 3rd and 5th harmonics were well within legal 
> limits.   When fed the "ham way" of the 50s and 60s, all that "nice" was 
> gone and there was plenty of ugliness.  Thus the rep for TVI and pink 
> tickets which became
> "beer talk" at ham club meeting, then fodder for magazine articles, then 
> became legend and finally
> matters of  near-religious dogma; unshakeable.
>
> If one abuses technology, bad things result.
> It isn't the fault of the technology; the problem
> is the lack of understanding and plain, old stubborn
> "Joe and Jim said it's this way so by God it's this way."
>
> There was/is nothing wrong with the design.
> There was/is plenty wrong with the lack of
> understanding and of effort to understand
> the transmitters before operatiing them.
>
> As far as doing what one wants with one's own
> property:  I can't argue that it's legal to do so,
> but why would one want to "do what one wants"
> in a way that not only results in a poor outcome,
> but causes needless destruction to one's property?  I mean, you can 
> sledge-hammer your new Chevy
> if you want; it's "yours."  But don't then complain
> because you can't rid to the ham club meeting in it.
>
> 73 Dave S.
>
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