[BC] MORE WESTINGHOUSE 50 HG

[Byrne, John H (COE Engineering)]

The RCA 50E installed at WCAU in 1941 was plate modulated. 


-----Original Message-----
From: broadcast-bounces at radiolists.net
[mailto:broadcast-bounces at radiolists.net] On Behalf Of
DHultsman5 at aol.com
Sent: Tuesday, January 08, 2008 11:28 PM
To: broadcast at radiolists.net
Subject: Re: [BC] MORE WESTINGHOUSE 50 HG

In a message dated 1/8/2008 6:35:39 PM Central Standard Time,
stanleybadams at yahoo.com writes:

> WAS IT DRIVEN BY 5 KW UNIT LIKE GE, RCA AND WESTERN ELECTRIC?  ALSO 
> LOOKING FOR MORE INFO ON STATIONS THAT HAD THIS RADIO..

The Western Electric transmitters were mostley modulated in a low level
RF stage by modulating the grid of and RF driver tube.  After that stage
the amplifier following were normally linear or of Doherity design.

Early RCA transmitter were not plate modulated and used linears to
achieve 
their high power at low efficiencies.   I am not certain which RCA was
the first 
50 kW. Plate modulated rig the 50E or the 50F.

In the case of all Western Electric transmitter until the last of their
line and the first of the Continental line, the modulation was done by
varying the 
bias on the peak tube and the carrier tube..   If you had a 5 kW. rig
that rig 
had a 5 kW. Doherity amplifier,  ie: the WE 405A/B series transmitter
was the driver for the WE 407, 50 kW.  There were two Doherity amplifier
one at 5 kw. 
driving another for 50 kW.

In the case of early RCA transmitters a 5 kW. transmitter would use the
modyulator as an audio driver to the 50 kW. Class B modulator tubes.
The 5 kW. RF stage typically an 891 or 892 drove the parallel tube Class
C RF stage modulated by the above. In this way the lower power
transmitter was used in the higher power transmitter.

In the case of the Collins 20V series 1 kW. transmitter the 4-400's in
the modulators were changed  to drive the Modulator grids of the Class B
modulator in the 21E & 21M, 5 and 10 kW. transmitters.  The first
cabinet was the RF and audio driver for the 5/10 kW. modulator and PA
stages.

Nearly all RCA's from the late '40's till the low power 5L and 10L
Lower power Amplifiers used the RCA 1 kW. cabinet as an RF driver and a
modulator driver in their higher power 5 and 10 kW. rigs.

Dave 


**************
Start the year off right.  Easy ways to stay in shape.
     
http://body.aol.com/fitness/winter-exercise?NCID=aolcmp00300000002489
_______________________________________________

The BROADCAST [BC] list is sponsored by SystemsStore - Your Premium
Supplier Of Components To Build and Maintain A Technical Infrastructure
www.SystemsStore.com       Tel: 407-656-3719    Sales at SystemsStore.com