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 Post subject: untuned rf amplifier for a regen receiver
PostPosted: Jul Tue 02, 2019 6:51 pm 
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Joined: Jan Fri 04, 2019 11:32 pm
Posts: 34
Location: Sheridan, Wyoming
I am building a regen, and would like to place a 12sk7gt tube, untuned rf amp between the antenna and detector tube. It seems to me that the signal could enter through a attenuator pot ,from the antenna post, to the grid of the 12sk7gt tube, and exit the plate of the tube,as an amplified signal,then, through a 4 pf mica cap. on to the antenna winding on the tuning coil form. From there, the signal would be induced to the tuning coil, and then on to the grid of the 12j5gt detector tube, after passing through the grid capacitor on the screen of the 12j5gt tube. If I have not lost you yet, could someone show a schematic of such an arrangement? Any help appreciated, and brother, do i need it!!!!!!william


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 Post subject: Re: untuned rf amplifier for a regen receiver
PostPosted: Jul Tue 02, 2019 8:02 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1874
I've done a bunch of them. I have found that the grounded grid RF amps do not help anything.
Simply putting the antenna on one end of a 5K pot and the ground on the other is of value. Feed the detector with a gimmick capacitor.

You do not want a high gain tube as an un-tuned RF amp. IT will be noisy. You want low gain. The point is to isolate the detector from the antenna. Using a pot an a gimmick cap does that fine.

Attached is an example of how I have done it.


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dualtriode.jpg
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 Post subject: Re: untuned rf amplifier for a regen receiver
PostPosted: Jul Tue 02, 2019 11:02 pm 
Member

Joined: Jan Fri 04, 2019 11:32 pm
Posts: 34
Location: Sheridan, Wyoming
Thank you Scott. I was pretty sure it could be done. What low gain tube do you recommend? Triode or pentode....William


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 Post subject: Re: untuned rf amplifier for a regen receiver
PostPosted: Jul Tue 02, 2019 11:23 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1874
Triode like 6j5, 6c6 or equivalent.

Mike Peebles added an RF amp to his 2-tuber, different but works well. He used a 1T4.
http://peeblesoriginals.com/catalog/manuals/PO-425.pdf


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 Post subject: Re: untuned rf amplifier for a regen receiver
PostPosted: Jul Thu 04, 2019 12:55 am 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 12229
Location: Powell River BC Canada
typo? Triode like 6j5, 6c6 or equivalent. 6c5 maybe.

_________________
de
VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca


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 Post subject: Re: untuned rf amplifier for a regen receiver
PostPosted: Jul Mon 08, 2019 5:15 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1874
Yes a typo.
6c5, 6j5, 6sn7, etc octal
6c4 miniature

try a medium or low mu triode. Hi mu tubes seem noisier


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