[ARC5] Re: Harmonic "suppression" in ARC-5s

[Bob Macklin]

This is the way I feel about. Over coupling link coupled final is never a
smart thing to do.

To use an ARC-5 Tx with a better antenna than they were designed for
eliminate the roller inductor and couple the link output into matchbox that
can provide the proper coupling. And that is not a classic T-network tuner.

Bob Macklin
K5MYJ
Kent (Seattle), Wa,
"Real Radios Glow in the Dark"

----- Original Message ----- 
From: "J Forster" <jfor at quik.com>
To: <kgordon2006 at verizon.net>
Cc: "Bob Macklin" <macklinbob at msn.com>; "ARC-5" <arc5 at mailman.qth.net>
Sent: Monday, December 15, 2008 8:13 AM
Subject: Re: [ARC5] Re: Harmonic "suppression" in ARC-5s


> Not quite, I think.
>
> There is a classic experiment in physics with two tuned circuits, each
composed
> of a large coil and resonating capacitor. First you sweep a single coil
then
> bring the second coil into coupling range, and the peak "splits" to form a
> double tuned (rabbit ears) display. The degree of splitting is dependent
on the
> coupling.
>
> In the ARC-5 Tx, there are two resonant circuits:  The plate tank & the
> rollerductor-antenna capacitance. They are variably coupled by the link.
>
> Too much link coupling will couple the two circuits too tightly and reduce
the
> overall Q of the system by double peaking, leading to reduced harmonic
> suppression.
>
> So, I'd think to achieve maximum suppression, you'd want to use only
enough
> coupling to get the power out, and no more.
>
> -John
>
>
> ====================
>
> Kenneth G. Gordon wrote:
>
> [snip]
>
> >
> > Both the link settings AND the loading coil settings, in conjunction
with
> > the various capacitances involved, whether antenna or other wiring,
> > constitutes, automatically, a kind of harmonic attenuator, since they
> > ARE frequency dependent and frequency selective.
> >
> > If they weren't, then it wouldn't matter how you set either the link or
the
> > loading coil, as long as the final was tuned to the same frequency as
> > its driver was.
> >
> > You had to adjust the loading coil, and the link, to achieve proper
> > power into what ever antenna your airplane carried. And, if you
> > changed frequency significantly, you had to RE-adjust those for proper
> > power output.
>
> [snip]
>
>