813 rig

[ve6pg]

..somewhere on here is a dwg of a rig using 2 813s...cant seem to find it again. can anyone assist?..

..tim..

..sk..

[Pete, WA2CWA]

http://www.amwindow.org/tech/htm/813/813.htm

[VA3AEX]

Tim, good talking to you today on 40M even with my DX100 sorching ...  got the Ameco plugged in but small receive loop doesn't seem to giving me anything...Alex

[W2WDX]

To this day I am still embarrassed about that schematic. If I had the software I have now, not to mention the technical knowledge, it would have been done much better.

Maybe one day I redo it and send it in. Heck I was using some scribbled drawing Tom K1JJ originally submitted it with. But the drawing doesn't matter, the performance of the rig is what matters. And this things is a beast.

John, W2WDX

[Steve - K4HX]

Why be embarrassed? The drawing you made was a heck of a lot better than the one I had up there previously. Your effort is appreciated and has been used by more than one AMer.  TNX!

[KL7OF]

I built that rig from that schematic.......works FB OM...altho I wear glasses now

[ve6pg]

..thanks...i knew the dwg was about somewhere...i have obtained a homebrew amp, grid driven, thru a bank of swamping resistors...nice piece...i just wanted something to refer to...hope to get it in here shortly...


..tim..

..sk..

[ve8xj]

This is great I have been looking for a schematic like this for a while.

Stupid question.....The neutralizing plate on the bias circuit is new to me though it does make sense. Is as the schematic suggests one plate on one tube all that is required ?? Or am I naturally supposed to assume that both tubes get the same treatment ?

Steve : Any pictures from the inside of your rig would be great someday to get a sense of how some people have laid this out in the past.

[K9PNP]

To this day I am still embarrassed about that schematic. If I had the software I have now, not to mention the technical knowledge, it would have been done much better.

Maybe one day I redo it and send it in. Heck I was using some scribbled drawing Tom K1JJ originally submitted it with. But the drawing doesn't matter, the performance of the rig is what matters. And this things is a beast.

John, W2WDX

I wouldn't worry about that.  I looks a lot better than the "draft" schematics for some of my hmbr equipment.  Some of them are still on the envelopes or whatever I had at the time.  As long as it works...

[K1JJ]

This is great I have been looking for a schematic like this for a while.

Stupid question.....The neutralizing plate on the bias circuit is new to me though it does make sense. Is as the schematic suggests one plate on one tube all that is required ?? Or am I naturally supposed to assume that both tubes get the same treatment ?

Yes, you have it correct - just one tube gets the treatment.

Since the two tubes are in parallel and in the same phase, a sampling from one plate off one of the tubes is all you need to pass some RF to the feedback circuit.

You can experiment with the size of the plate and the distance from the tube so that the adjustment capacitor tunes in the middle of its range. When doing a "cold" neutralization, you will see the feedthru signal null out quite well when everything is working right, indicating full neutralization and cancellation of the tube's undesirable feedthru capacitance.

T