The Amp Garage

I'm thinking that this will be the last update, before a build. I managed to put together something of a standard schematic. It's still not entirely like most, but it's a start. So with this revision, I have included the layout, the new schematic, my original format schematic, a Bill of Materials, a...

I updated the drawing, and left it as the same revision. The major change was to correct the component labeling to have sequential numbers. I found an error where I had a ground in the wrong place on the Tone Stack. I had to add a missing capacitor to the Volume pot, giving it the next highest numbe...

Here's the latest revision. The same schematic, but I've completed a layout. When I have the chance, I will draw a schematic that conforms more to convention. In the meantime, take a look and comment please.

Jack

12Jan14 - Note: See below for update to rev-D.

Here's an updated version of my concept drawing of 10thTx's. He redrew it to a more readable schematic, along with a layout. If his doesn't get posted here, it can be seen over on the Hoffman Amp Forum.

Jack

11Jan14 - Note: See rev-D below

Thanks for posting. I've got lots of the little 7-pin tubes, and some drawings of my own, that I hope to turn into builds. I can't remember if I posted it here, but I have a hard time keeping things in my head these days. So, if there's math involved, I put it into a little program: 12/21/13 Amp Uti...

Here's a concept drawing that I made of Jeff's circuit, using a triode as the CF. And rather than his PI, I used the second triode in the tube as a Cathodyne PI. Saved adding another tube. The PI was taken from Merlin's book. Forgive the unconventional schematic. I draw literally like it might be a ...

I've been away from Amateur Radio for so long. I was a regular listener, back in the day. With an occasional contact. I didn't chase contacts for the sake of such. If I heard something really interesting (mostly non-radio), I would politely step in with my call. If after the second time I wasn't ack...

It would be fun to get some of us TAG hams together on the air. I have a modest station up & running on 15, 20, and 40 meters. But I don't get on the air much any more either unless I have a reason to. Maybe this would be a good reason. The last time I tried to tune up my Icom 745, I pressed the ke...

de KS4VS.

Mine is current, but I've been inactive so long that I've forgotten my code.

Amps have been a fun return to tubes, in the recent few years.

Jack

That's great, Jack! I'll be happy to help where I can, and probably be posting updates here as I get more experience. Get a good soldering rig if you don't have one already- there are some fine-pitch pads on the board. I do need to use something different, for this build, as my typical soldering se...

Martin - I'm very impressed with your invested time, on this instrument. I recently purchased one, to build over the Winter. I am just now discovering this thread, and have it bookmarked. I will try to post pictures of my contruction, but thinking it will be drawn out for a while. Thanks for sharin...

In your schematic, one of the inputs has a closed circuit jack that grounds the signal when nothing is connected. The other jack is an open circuit, but the grid is still tied to ground through R1, acting like a grid leak resistor. Verify that your closed circuit jack is working, to complete this pa...

Most of my experience, since my return to tubes in recent years, has been the repair/restoration of old amps. 90% of what I've found on them, with the 60Hz hum (regardless of pot position) has been the decoupling caps in the power supply. As yours is a new build, I'd say begin by lifting the signal ...

I know that this is an old thread, but I'm interested in the #3 schematic. Did you ever get around to making a sketch of yours? Thanks.

Jack