Jim, for your information, I have a Western Electric 451A-1 transmitter (250 watt class) that uses Doherty circuitry. It has 6 tubes in the final that are similar to 211 type tubes.
It was placed in service back in 1947 and I picked it up last year to restore. Any idea how effective the modulation is compared to Class B, plate modulation? Thank you. Dave, W3ST Secretary to the Collins Radio Association Publisher of the Collins Journal www.collinsra.com ----- Original Message ----- From: "Jim Bromley" <[EMAIL PROTECTED]> To: "AM Radio List" <[email protected]> Sent: Sunday, December 21, 2003 6:30 AM Subject: [AMRadio] Re: looking for linear amplifier > Don, K4KYV, sez: > > > Continental Electronics, a long time manufacturer of > > broadcast transmitters, never offered a plate modulated > > product. Their advertisements always pointed out that > > from a BC station's vantage point, low level and high > > level modulated (tube type) transmitters are about > > equally economical to operate in terms of the electric > > bill for running the transmitter. > > Yeah, but their linear amplifiers were Doherty types > that achieved high carrier-level efficiency by use > of a relatively complex two-tube (carrier and peak) > scheme. They used that method to get up to the > 1 Megawatt level for BC transmitters. However, once > PWM became widely accepted, they adopted that for > most of their transmitter line. > > > Actually if you want to build a high power high level > > homebrew transmitter, there is no need to spend megabucks > > to purchase a custom built mod transformer. There are > > plenty of tube type broadcast transmitters sitting > > around all over the country that have been removed from > > service.... > > Will it fit on my desktop and weigh less than 100 lbs? > :-) > > Jim, K7JEB > Glendale, AZ > > _______________________________________________ > AMRadio mailing list > [email protected] > http://mailman.qth.net/mailman/listinfo/amradio
