[ARC5] " ARC-5 " Transmitter Antenna Matching.

[J. Forster]

Marty Reynolds wrote:

> I got interested in the 1:4 broadband xfrmr 2 yr.s back w. NO success.
> Reason was no reactrance cancellation

Of course not.

> An antenna exhibits
>
>      an impedance of    Z=R+jX
>
> Power is only disipated in R, X leads to swr & big unwanted voltages.
> Job 1 in 'conjugate match' is getting rid of X.

VSWR can be caused by a mismatched load, even in a purely resistive system. L's
and C's cause 'resonant step-up' at resonance.

> One thing.  If you use more Xc than needed, you can compensate with the
> loading coil (int'l Xl).  This is actually mentioned in a 1950 ART13a book
> & the series cap was an accsy.

On ARC-5s and 19 sets, the antenna circuit is designed to operate series
resonant. This resonance can be high Q if the radiation resistance is small
(from an electrically short antenna). This helps with harmonic suppression.

I simply do not understand why hams (and some others) think they are better
designers than those who made the sets in the first place. It is simply NOT SO
in >99% of the cases. Most, if not all, mods reduce performance IMO.

-John