Questions on Paraglow kit and pic

[fitz]

I am building an old Paraglow kit and had a couple of questions. I have attached a pic of work in progress. Still quite a bit more work to do. I am going at a relaxing pace by just working for about an hour a night. I'm in no big hurry. lol

1. I want to implement the PGP8.1 center tap switch. Will I run into any problems with hum if I run a twisted magnet wire pair(like the original ground wire) from the center tap lug on the transformer to a switch next to the original power switch ? I would like to keep the two switches next to each other just for aesthetics but wondered about such a long run across the chassis.

2. Has anyone had any experience with mounting the hum pot shaft up thru the chassis ? I was thinking of doing this in the center of the chassis between the input jack and the power transformer. But again, I am worried about possible hum problems with the extra heater wiring.

Thanks for any help.

 

[RPMac]

I've thought about inverting the hum pod so the shaft is toward the top plate and drill a hole to align with it. I don't think the shaft of the stock hum pot is long enough to come through the top plate for access, so a slot would have to be cut in the shaft end to use a screw driver to adjust. Or get a hum pot with a longer shaft.

I thought about the switch idea, but bought the soft start kit for this issue. But the room under the hood for them, just isn't there.

You may not like this idea, but if you plan to tweak later, you may want to consider a suggestion from Paul B. Buy some Paramount top plates and build the Paraglows on them. I intend to do this some day, but can't take the Paraglows out of my system.

Because of the direct coupling, you will be limited on the 2A3 tubes you can use.

 

[Grainger49]

I brought my Paramour (1) hum pots through the top plate.  It worked well.  If there is room for the nut and any thread left, you can bring it through the plate.

 

[Paul Joppa]

You may or may not have noticed, but we reversed the hum pot some years ago - it's a handy idea. I did it on my Original SEX amps when I converted them to 300Bs long ago, placing the pot as you suggest in the center (left/right).

The center-tap standby switch has a long history, but I have always opposed it. Too much voltage is switched, and it will eventually destroy the switch. If you must, is a 15-amp 240v switch rating. The return wire should ground the center tap at teh same place it is otherwise grounded, and twisted wire is ideal for the length from there to the switch and back. However, the voltage between the wires is the full DC voltage, which is 500v or so with the PGP8.1 and no load, so you want to use 600-v rated wires. They are not that common, most wire is 300v or less, and magnet wire is unreliable as a high voltage insulator, there are too many possible holes or nicks in the insulation.