The AM Forum

No heavy iron here!   See page 54.  Maybe 6550 or 4D32 instead of 2E26.....

http://www.americanradiohistory.com/Archive-Radio-News/50s/Radio-News-1951-08-R.pdf


Matt

thanks for bringing this one here, Matt .... I downloaded and printed the article .... this looks quite interesting and has my attention .... does anyone have experience with this type of am generation ?

This is something I would like to see in action.

I would start with his original circuit, and check it out big time.

If it worked well, I would make a "Big Brother" using 6550's or 4D32 in the final stage.

From what the author says, European AM braodcasters used this method.  It must do a decent job, else the regulators would get upset.  I like the idea of just one small audio tranny!  Hammond probably has plenty of candidates for the job.

For a small rig, 807's would probably do instead of 2E26's. 

One I complete my chassis punch set completed, it will be time to build a thing or two. 

I believe Steve once built something like this set.

Matt :-)

Look up outphasing modulation. Also, RCA had a variation for AM transmitters.

Ampliphase, they made one that was supposed to put out 250 kw for a Mexican station.
http://www.fmamradios.com/Ampliphase.html

Yes!  The legendary Mexican X stations!  The Doors song Texas Radio was inspired by Mexican X transmitters.  Jim and Ray used to listen to the X stations when they were kids.

Here on AM Fone, we is stoned immaculate........but not while working around plate tank circuits and HV power supplies.  :-)


https://www.youtube.com/watch?v=PhZFhvG6OkM


Matt

there is a remark floating around that this might be the old european amplidyne system ...a google search of this seems to turn up nothing ... amplidyne as exists is an electromechanical method by GE for another purpose

this article is intriguing .... imagine, a very efficient relatively simple lightweight tube transmitter .... hooked

'Cool" and 'easy' in theory, but the phasing alignment required to make it go, and the stickler of tough-to-QSY made both phasing and Doherty amplifiers difficult to implement for amateur use.

It will work fine for a ham, if you don't move too many kHz within one band.

So build a big-ass one and set it on 3885 for instance and rule the roost with kW's.  They are some of the most efficient linear amps ever designed.

73DG

ps....all the Mexican super-powers were licensed within international radio treaty provisions.

XERF outside of Juarez was allocated 250kW, but financial realities dictated it was not run at that level for long and today it runs 100kW.  Making a buck, even with a lot of oomph, is tough anywhere, especially in Mexico, where KWh costs are high.

Ampliphase, not Amplidyne...

AM tx designs have evolved considerably past the Doherty, Ampliphase and PDM systems.

The DX-series AM broadcast transmitters of Harris Corporation directly generate their fully-modulated r-f output power using digital techniques.

Measured/rated efficiency for overall a-c input power to fully-modulated r-f output power is better than 80%, and with very low distortion.

They have been supplied at output power levels up to 2000 kW (unmodulated).

http://mze.com.ge/uploadfiles/Radio%20Transmissions/DX%20AM%20Transmitter%20Family/DX%20AM%20Transmitter%20Family.pdf