"That is WAY too small!"
"Where do you think you're sticking that??"
"Wow, nice wood."
With an extra 120V secondary power transformer from Antek (w/ 2 x 6.3V heaters @ 2A) , some 6BQ5's and 12AT7s from my stash of tubes, and a few feet of nice walnut left over from another project, I've embarked on an extremely small footprint RH84 build. The top plate on the chassis measures 6" x 10". Because of the small size of the chassis (and the 120V secondary), this will use a voltage doubler to achieve 300V B+ (see this thread where I talked about the PSU).
Here's a layout picture now that I've received all my parts:
The walnut is 1/2" thick mitered at the corners and the top plate is 1/8" aluminum. I used small blocks at the corners to support the top plate and to reinforce the miters. The bolt near the front left is for the toroid under the deck, the choke (back left) is a Hammond, and the OPTs are 5W Transcendars (I'm very excited to use these).
All holes are drilled and the switch/IEC/fuse is mounted (upper right of this pic):
As you can see, this is a tight fit (that's what she said!). I'll mount the voltage doubler 'module' (built on a terminal strip) just behind the power transformer. I'm still working on the best place to fit the filter caps (2 x 220uf, rather large). Anyone have practical advice on placement of these with regards to the OPTs or tube sockets? I'm thinking 'between' the OPTs on the underside to give me as short as possible B+ runs after the filtering.
Finally, here we are with everything test fit:
I'm thinking inputs on the front right of the top plate and volume control on the right side of the front walnut 'apron'.
So far, so good. I'm a bit worried about how tight the power supply is, but you know what they say about good things in small packages (that's what she said!).
"Where do you think you're sticking that??"
"Wow, nice wood."
With an extra 120V secondary power transformer from Antek (w/ 2 x 6.3V heaters @ 2A) , some 6BQ5's and 12AT7s from my stash of tubes, and a few feet of nice walnut left over from another project, I've embarked on an extremely small footprint RH84 build. The top plate on the chassis measures 6" x 10". Because of the small size of the chassis (and the 120V secondary), this will use a voltage doubler to achieve 300V B+ (see this thread where I talked about the PSU).
Here's a layout picture now that I've received all my parts:
The walnut is 1/2" thick mitered at the corners and the top plate is 1/8" aluminum. I used small blocks at the corners to support the top plate and to reinforce the miters. The bolt near the front left is for the toroid under the deck, the choke (back left) is a Hammond, and the OPTs are 5W Transcendars (I'm very excited to use these).
All holes are drilled and the switch/IEC/fuse is mounted (upper right of this pic):
As you can see, this is a tight fit (that's what she said!). I'll mount the voltage doubler 'module' (built on a terminal strip) just behind the power transformer. I'm still working on the best place to fit the filter caps (2 x 220uf, rather large). Anyone have practical advice on placement of these with regards to the OPTs or tube sockets? I'm thinking 'between' the OPTs on the underside to give me as short as possible B+ runs after the filtering.
Finally, here we are with everything test fit:
I'm thinking inputs on the front right of the top plate and volume control on the right side of the front walnut 'apron'.
So far, so good. I'm a bit worried about how tight the power supply is, but you know what they say about good things in small packages (that's what she said!).
Here's where I'm at for cap placement:
The caps on the right are for the voltage doubler. I'd mount them to a terminal strip along with the required diodes and fix it to the wooden apron. I'm still playing with placement on the filter caps (the ones on the left). I'd like to use the mounting screw of the terminal strip they're on as the star ground point. Any foreseen issues with having the caps so near the OPT leads? I could also move them to between the two OPTs, but doing so then gets in the way of the speaker binding posts to a certain degree.
The caps on the right are for the voltage doubler. I'd mount them to a terminal strip along with the required diodes and fix it to the wooden apron. I'm still playing with placement on the filter caps (the ones on the left). I'd like to use the mounting screw of the terminal strip they're on as the star ground point. Any foreseen issues with having the caps so near the OPT leads? I could also move them to between the two OPTs, but doing so then gets in the way of the speaker binding posts to a certain degree.
SOAF = significant other acceptance factor.
McMaster-Carr is a source of "acorn" nuts and many other useful items.
McMaster-Carr is a source of "acorn" nuts and many other useful items.
Shot of the voltage doubler 'module':
The diodes will be run to the separated tab along with a transformer secondary lead and the middle tab on the main terminal strip is the other connection for the secondary. The unsoldered outer tabs will be B+ and ground. Also pictured is a CL90 on the power switch. Is this the best place for it anyone?
Here's another glamor shot to make sure this all fits:
Above includes binding posts. I may switch these out for something fully insulated, but I had these in my parts stash and gold = high SOAF.
Tim to break for the day as I realized I forgot to order a couple of things (10uf power rail cap and bleeder resistors) and the beer catalog cover has reminded me that there other important things to do with my day...
The diodes will be run to the separated tab along with a transformer secondary lead and the middle tab on the main terminal strip is the other connection for the secondary. The unsoldered outer tabs will be B+ and ground. Also pictured is a CL90 on the power switch. Is this the best place for it anyone?
Here's another glamor shot to make sure this all fits:
Above includes binding posts. I may switch these out for something fully insulated, but I had these in my parts stash and gold = high SOAF.
Tim to break for the day as I realized I forgot to order a couple of things (10uf power rail cap and bleeder resistors) and the beer catalog cover has reminded me that there other important things to do with my day...
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There really should be a fuse between the mains and the power switch, since the switch is apparently plastic in this instance you could get away with placing it after the switch. With a metal switch in a metal chassis a fuse between it and the mains will protect against a short to chassis assuming that the chassis is properly grounded. (It has happened to me)
Never done point to point with a busbar before.
"Be gentle, this is my first time."
Any tips? It's grounded on the upper right, where the star ground will be located. Input grounds will be at the left terminal strip side (bar is not connected to chassis here). I don't know where the gigantic Orange Drops I ordered are going to fit. Might have to find a smaller coupling cap.
Also, what think ye of the 12AT7 heater wiring? I went right down the middle of the socket so it could stay well twisted. I could also run one connection around the outside (this is 6.3V parallel heater wiring).
"Be gentle, this is my first time."
Any tips? It's grounded on the upper right, where the star ground will be located. Input grounds will be at the left terminal strip side (bar is not connected to chassis here). I don't know where the gigantic Orange Drops I ordered are going to fit. Might have to find a smaller coupling cap.
Also, what think ye of the 12AT7 heater wiring? I went right down the middle of the socket so it could stay well twisted. I could also run one connection around the outside (this is 6.3V parallel heater wiring).
Oh yeah. I hope this busbar arrangement works out.
Is that an Orange Drop in your pocket or are you just happy to see me?
Had to switch to bigger terminal strips because things were getting too cramped. Luckily I had only soldered at the sockets so far.
So I've got a 100k pot on hand, but I'm not sure how to squeeze it in here. I do not have a proper preamp at the moment or I wouldn't bother. I may have to route out the rear of the front panel to make it work because there just isn't room for a bracket w/ extension in there, unless it's right next to the power transformer. I suppose this entire build is pretty much right next to the power transformer, though...
Is that an Orange Drop in your pocket or are you just happy to see me?
Had to switch to bigger terminal strips because things were getting too cramped. Luckily I had only soldered at the sockets so far.
So I've got a 100k pot on hand, but I'm not sure how to squeeze it in here. I do not have a proper preamp at the moment or I wouldn't bother. I may have to route out the rear of the front panel to make it work because there just isn't room for a bracket w/ extension in there, unless it's right next to the power transformer. I suppose this entire build is pretty much right next to the power transformer, though...
I'm saving all the best innuendo for last...
Transformers and choke mounted. Running the B+ and choke leads to the filter network. That's the Nichicons. The bigger and blacker, the better.
It just barely fits in this little box:
Oiled up and ready to party:
Uh oh, we got a hummer:
So I flipped her back over and gave her a once over with my red hot iron. I'm pretty sure this was the culprit:
Transformers and choke mounted. Running the B+ and choke leads to the filter network. That's the Nichicons. The bigger and blacker, the better.
It just barely fits in this little box:
Oiled up and ready to party:
Uh oh, we got a hummer:
So I flipped her back over and gave her a once over with my red hot iron. I'm pretty sure this was the culprit: