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 Post subject: RF amplifier for low voltage vacuum tube raython 6418
PostPosted: Nov Wed 01, 2017 12:31 am 
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Joined: Feb Tue 14, 2017 5:57 pm
Posts: 2
Build nice one vacuum tube using raython 6418 18 volts on plate shortwave AM radio . Local am stations very loud ssb cw very low can't use outside antenna, using super fine magnetic wire for antenna reception is good L1 L2 triple strand wire very low ac hum . need RF amp using 6418 and how can I post a picture my radio I call it the handshake radio thank you


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 Post subject: Re: RF amplifier for low voltage vacuum tube raython 6418
PostPosted: Nov Thu 02, 2017 1:29 am 
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Joined: Aug Thu 06, 2015 2:20 am
Posts: 108
Just a suggestion.

I frequently build semiconductor SW regen receivers.

Using a 3 inch long ferrite rod antenna with about 10 turns I listen to both the 80 and 40 meter bands along the East coast of the U.S. nightly with no external antenna.

With regen receivers, the principal advantage to using an RF amplifier is to isolate the antenna from receiver radiation and preventing the antenna from loading the receiver.

My opinion is that there is little to be gained by using an RF amplifier with a regen receiver.

My suggestion is to try a ferrite rod antenna.

The schematics below use a Colpitts oscillator configuration which uses the intrinsic Base-Emitter capacitance as one of the feedback capacitors.


Attachments:
Favorite regen 2.jpeg
Favorite regen 2.jpeg [ 25.77 KiB | Viewed 291 times ]
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 Post subject: Re: RF amplifier for low voltage vacuum tube raython 6418
PostPosted: Nov Thu 02, 2017 6:07 am 
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Joined: Feb Tue 14, 2017 5:57 pm
Posts: 2
My receiver is a little more complex using 2 type of coils ,main coil antenna directly off grid 1covers 150 khz 6000 khz second coil 8000 khz 1180 on am radio band. second coil sound like crystal tuned very clear locks on no hand effects, standard am band super loud. Thought maybe house wiring, am very good even outside. In park open area also. ssb cw very clear volume low. ,trying different inductors ,guess band select works best. might add to more stages in front end using 6418. mixer rf amp bfo wanted to stay with vacuum tubes @ 10ma. thank you for feed back ,can I post picture of my radio ?? 73


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 Post subject: Re: RF amplifier for low voltage vacuum tube raython 6418
PostPosted: Nov Thu 02, 2017 6:14 am 
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Joined: Aug Thu 06, 2015 2:20 am
Posts: 108
KARLTON wrote:
can I post picture of my radio ?? 73

Love to see it. I have always been fascinated by those low voltage tubes. Almost like using transistors or perhaps more correctly FETs.

Why not wind a couple of new coils, horizontally oriented on ferrite rods?


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