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THE AM BULLETIN BOARD => Technical Forum => Topic started by: Jim/WA2MER on January 17, 2018, 06:07:10 PM



Title: Clamp Modulated Transmitter Using 829B
Post by: Jim/WA2MER on January 17, 2018, 06:07:10 PM
Many years ago I found a schematic of a clamp modulated HF transmitter that was designed around the 829B. I was planning to build the thing and I had done a design modification to add 160 Meter capability, but the project never got off the design sheet. The information I had on the rig is long gone, and I'd like to revisit it. Does anyone reading this have any idea where I might find information on such a rig? Darned if I recall where I first saw it. Thanx.


Title: Re: Clamp Modulated Transmitter Using 829B
Post by: DMOD on January 17, 2018, 11:36:08 PM
In my view, Clamp modulation is a power-wasting method to screen modulate any tube.

A better method is to use a 6EW7 in a cathode follower configuration.


Phil - AC0OB


Title: Re: Clamp Modulated Transmitter Using 829B
Post by: Jim/WA2MER on January 18, 2018, 09:31:51 PM
Thanx for your input, Phil. I downloaded your circuit and will consider using that scheme. I would still like to find that 829B circuit though, at least for the RF design. I have an 829B floating around here that I'd like to press into HF service because...well, just because. If I can't find the circuit I'll have to design it from scratch I suppose.


Title: Re: Clamp Modulated Transmitter Using 829B
Post by: DMOD on January 21, 2018, 02:09:27 PM
The 829B is an interesting tube for sure.

Here is one such schematic:

P. 72

http://www.americanradiohistory.com/Archive-Radio/Handbooks/Radio-Handbook-12-1949.pdf

Phil - AC0OB


Title: Re: Clamp Modulated Transmitter Using 829B
Post by: Jim/WA2MER on January 21, 2018, 07:35:14 PM
Got it Phil, thanx. - Jim
AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands