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Author Topic: Anyone recognize this hamfest purchase?  (Read 1256 times)

AC9QC

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Anyone recognize this hamfest purchase?
« on: August 14, 2021, 09:44:18 PM »

Kind of intrigued by it. I think I gave a fiver, I just couldn't let it be an orphan and figured it'd be a cool wall hanger if worse came to worse. The tube compliment is:
-6AQ5
-6L6
-807
-4-65A





There's a built in filament transformer and the center tap that would normally be grounded seems to be connected to a phono jack like it was meant to key the tube. Not really sure what's up there. It seems like a lot of stages for just a basic osc/power tube transmitter in CW. Definitely interested in what people have to say on it.
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VK3LU

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Re: Anyone recognize this hamfest purchase?
« Reply #1 on: August 15, 2021, 01:13:01 AM »

Hi,
Is there any chance of getting the images reduced in sized? It is impossible to view them.

Nev
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W1RKW

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Re: Anyone recognize this hamfest purchase?
« Reply #2 on: August 15, 2021, 03:30:52 AM »

this depends on the browser being used but if you right click on an image you'll get some other image viewing options.
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VK3LU

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Re: Anyone recognize this hamfest purchase?
« Reply #3 on: August 15, 2021, 03:59:33 AM »

I am using a Samsung tablet and there is nothing I can do about image size..

Nev
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W9IQ

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Re: Anyone recognize this hamfest purchase?
« Reply #4 on: August 15, 2021, 04:05:04 AM »
















- Glenn W9IQ
« Last Edit: August 15, 2021, 04:08:52 AM by W9IQ »
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

N8FVJ

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Re: Anyone recognize this hamfest purchase?
« Reply #5 on: August 15, 2021, 05:00:40 AM »

It is a transmitter with plug in coils for the frequency.
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OK4FX

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Re: Anyone recognize this hamfest purchase?
« Reply #6 on: August 15, 2021, 05:58:54 AM »

If there is a page with pictures which don't fit into your browser window size then you can paste small javascript into address bar and execute it.

For example, this code will resize all pictures wider than 800px to 800px:
Code: [Select]
javascript:var%20i,L=document.images.length;for(i=0;i<L;++i){document.images[i].style.maxWidth='800px'};false();
You can save this code into your browser bookmarks for convenience.
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Mira OK4FX

K8AXW

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Re: Anyone recognize this hamfest purchase?
« Reply #7 on: August 15, 2021, 11:05:11 AM »

To me it looks like a homebrew crystal controlled transmitter with what could be a link coupling to the antenna.

Does the piece of Plexiglas on the right move and does it have or provisions (holes) to mount a coil of 2 to 5 turns?
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A Pessimist is Never Disappointed!

K6BSU

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Re: Anyone recognize this hamfest purchase?
« Reply #8 on: August 15, 2021, 12:19:33 PM »

It's an interesting home brew.  Some good parts in there in case you want to turn it into something more useful.

Hard to imagine it takes an 807 just to drive a 4-65 pentode...unless that's an audio tube to modulate the screen grid?
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AC2EU

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Re: Anyone recognize this hamfest purchase?
« Reply #9 on: August 15, 2021, 01:57:28 PM »

i vote for "crystal controlled transmitter" as well.
Looks like a transmitter I built when i was 11, except i used an old radio chassis and octal tubes for the build.

A mentor looked at the effort and asked if the free form tank coil was "foot warmer" . I was crushed...

K6BSU

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Re: Anyone recognize this hamfest purchase?
« Reply #10 on: August 15, 2021, 07:54:40 PM »

I suppose you could plug a xtal into two pins of the octal socket.  OTOH, I wouldn't design a xtal oscillator using a 6AQ5 unless you could find a way to reduce power dissipation in the xtal. 

The next job is to reverse-engineer the circuit and publish the schematic diagram.  Until then, we are just guessing.
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KM1H

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Re: Anyone recognize this hamfest purchase?
« Reply #11 on: August 16, 2021, 07:03:28 AM »

Seems to be a 6AQ5/6L6/807 lineup which could be used from 160 to 10M with WW2 surplus FT-243 crystals which fit the empty socket.
Run the 807 as a doubler and no neutralization needed on the higher bands, that shield helps.

Hook up an external modulator for AM.

Carl
Ham and homebrewing since 1955

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K3UIM

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Re: Anyone recognize this hamfest purchase?
« Reply #12 on: August 23, 2021, 08:32:11 AM »

AXW: It looks like a 2 turn ling is incorporated on the far right of the coil.
I could be wrong, though. It may just be a bit of a gap in the turns. And BSU has a good suggestion about the schematic.
Charlie
« Last Edit: August 23, 2021, 08:35:44 AM by K3UIM »
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Charlie. K3UIM
Where you are: I was!
Where I am: You will be!
So be nice to us old fogies!!

AC2EU

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Re: Anyone recognize this hamfest purchase?
« Reply #13 on: September 20, 2021, 02:23:39 PM »


Too much work.
Probably got scrapped for the aluminum...

AC9QC

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Re: Anyone recognize this hamfest purchase?
« Reply #14 on: September 20, 2021, 07:42:14 PM »

No, not scrapped. I bought it as a wall hanger in all probability. The doublers are a genius idea though, I didn't think of that. When I get it out of storage I'll try to get something going on reverse engineering it.
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