[Amps] Plate modulator xmfr ?

[R.Measures]

On Oct 11, 2004, at 1:40 AM, peter.chadwick at Zarlink.Com wrote:

> One point to bear in mind is that the secondary of the modulation
> transformer has a lot of DC in it, which means that you need more iron
> (and probably an air gap) to avoid the core being saturated by the Dc 
> feed
> to the PA. This is apparently why modulation reactors are used - the
> transformer is designed for no DC, and feeds through a blocking 
> capacitor
> to the plate supply and ground, there being the 'modulation reactor' in
> series with the plate supply to avoid the AF being shunted. The 
> etchniques
> is apparently fairly common in the AM broadcast area for powers of 1 
> to 5
> kW.

-  This was common practice in ancient times, and it substantially 
improved the bass response of the modulation transformer, however, I 
doubt that very many "plate modulated" AM broadcast transmitters are 
presently being produced.   The excellent sounding AM signals that I 
have heard on the Ham bands use a low-level modulator IC and linear 
amplification.
>
cheers, Peter

Richard L. Measures, AG6K, 805.386.3734.  www.somis.org