High Voltage Non-HRM 100W Build Started

Overdrive Special, Steel String Singer, Dumbleland, Odyssey, Winterland, etc. -
Members Only

Moderators: pompeiisneaks, Colossal

User avatar
Bob-I
Posts: 3791
Joined: Thu Feb 02, 2006 10:06 pm
Location: Hillsborough NJ

Re: High Voltage Non-HRM 100W Build Started

Post by Bob-I »

Structo wrote:I know Bob but I have found that if the input side is 4-6v DC higher, I get the desired overtones.
And if I' hit 120MPH on the freeway, the laundry will be done. :wink: :roll:

What you have is a coincidence. If the tolerance of the grid load resistors is slightly different, bias of the tube changes etc, everything will be different.
BobW
Posts: 793
Joined: Mon Feb 06, 2006 8:15 pm
Location: Huntsville, AL

Re: High Voltage Non-HRM 100W Build Started

Post by BobW »

Tone Merc, you should be able to solder to the back of the pots unless they are AL (but doubt, it). You may need to scrape or slightly sand the back of the pot with a scotchbrite pad to get the surface down to bare metal. I have had no problems using this method.
You do not have the required permissions to view the files attached to this post.
User avatar
Structo
Posts: 15446
Joined: Wed Oct 17, 2007 1:01 am
Location: Oregon

Re: High Voltage Non-HRM 100W Build Started

Post by Structo »

The PEC pots have stainless steel covers.
Tom

Don't let that smoke out!
BobW
Posts: 793
Joined: Mon Feb 06, 2006 8:15 pm
Location: Huntsville, AL

Re: High Voltage Non-HRM 100W Build Started

Post by BobW »

Structo wrote:The PEC pots have stainless steel covers.
Thanks Tom, that explains it all...

Unless I'm missing something, I see no advantage to using a potentiometer w/ a stainless back, when the terminals would most likely oxidize first.
User avatar
jelle
Posts: 2391
Joined: Sat Feb 04, 2006 7:55 pm
Location: New Jersey

Re: High Voltage Non-HRM 100W Build Started

Post by jelle »

Bobw, what type of coax is that?

Thanks!

Jelle
User avatar
David Root
Posts: 3540
Joined: Fri Aug 04, 2006 3:00 pm
Location: Chilliwack BC

Re: High Voltage Non-HRM 100W Build Started

Post by David Root »

If you use the copper bussbar a la HAD you can use any kind of pot, and the more coax runs you have to pots the better you'll like it!

Took me a couple of amps to figure that out.
BobW
Posts: 793
Joined: Mon Feb 06, 2006 8:15 pm
Location: Huntsville, AL

Re: High Voltage Non-HRM 100W Build Started

Post by BobW »

Jelle, Thanks for noticing. The white coax is a MIL-C-17 version of RG-142. Teflon jacket and dielectric, 18 AWG Au/Cu center conductor and braid.
BobW
Posts: 793
Joined: Mon Feb 06, 2006 8:15 pm
Location: Huntsville, AL

Re: High Voltage Non-HRM 100W Build Started

Post by BobW »

David Root wrote:If you use the copper bussbar a la HAD you can use any kind of pot, and the more coax runs you have to pots the better you'll like it!
I agree David. If you zoom into the pic posted , you can see solid core wire attached to a few of the left pot terminals. I found once most of the wiring was in place, attaching the ground buss to the solid core pot jumpers made the build easier.
mlp-mx6
Posts: 1111
Joined: Sat Feb 04, 2006 4:24 pm
Location: NW Atlanta

Re: High Voltage Non-HRM 100W Build Started

Post by mlp-mx6 »

Bob, I do the same thing. I'll have 4 or 5 solid-core ground wire jumpers sticking straight out, and I'll just lay the buss bar in them and curl them around the bar, then solder. Works great.
Wife: How many amps do you need?
Me: Just one more...
talbany
Posts: 4696
Joined: Tue Mar 28, 2006 5:03 am
Location: Dumbleland

Re: High Voltage Non-HRM 100W Build Started

Post by talbany »

Iv'e attached both shield to the pot casings and to the SC ground buss and I honestly can't tell any difference noise .. The only thing I see that could be of any advantage is securing it to the pot casing helps secure the coax less chance of it breaking/bending at the pot lug if the buss get's bent for whatever reason..FWIW

Tony
" The psychics on my bench is the same as Dumble'"
BobW
Posts: 793
Joined: Mon Feb 06, 2006 8:15 pm
Location: Huntsville, AL

Re: High Voltage Non-HRM 100W Build Started

Post by BobW »

Thanks Tony, I agree. After seeing the initial chassis pics a few years ago, I followed HADs way of attaching the shields to the back of the pots.
Drumslinger
Posts: 374
Joined: Wed Nov 23, 2005 4:31 am
Location: USA

Re: High Voltage Non-HRM 100W Build Started

Post by Drumslinger »

I too like wiring the shield to the pots. Just makes things easier.
Chris333
Posts: 107
Joined: Sun Mar 05, 2006 3:20 am

Re: High Voltage Non-HRM 100W Build Started

Post by Chris333 »

BobW wrote:Jelle, Thanks for noticing. The white coax is a MIL-C-17 version of RG-142. Teflon jacket and dielectric, 18 AWG Au/Cu center conductor and braid.
Where do you get that stuff? My coax melts like butter whenever you get the iron near the conductor...
kd
Posts: 102
Joined: Fri Mar 17, 2006 2:10 pm
Location: South Texas

Re: High Voltage Non-HRM 100W Build Started

Post by kd »

Where do you get that stuff? My coax melts like butter whenever you get the iron near the conductor..
One source is Steve Slater at Apex Jr. Good prices too.
http://www.apexjr.com/




Ken
User avatar
Structo
Posts: 15446
Joined: Wed Oct 17, 2007 1:01 am
Location: Oregon

Re: High Voltage Non-HRM 100W Build Started

Post by Structo »

Chris333,

The melt back is primarily why a lot of us prefer Teflon insulated hookup wire and shielded cable.
It doesn't melt and although it is sometimes difficult to strip it pays dividends in appearance and functionality in the end.

Be careful when buying the shielded cable as a lot of it has high capacitance which can rob the high frequencies if you are not careful.

Besides, Alexander used it so I do too. :D
Tom

Don't let that smoke out!
Post Reply