Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Opry Audio on March 23, 2021, 08:14:27 pm
-
Seems like kind of a silly thing to be asking about but I’ve struggled with it! Occasionally I’ll wire up a shielded cable and it will look great.. on the volume pot for example, and it will ground the wiper of the pot. Can anyone offer some tips to insure that this doesn’t happen? Am I not leaving enough insolation on the ungrounded lead? I’m grounding only one side obviously. Also wondering how everyone gets the grounded lead looking so nice? I twist it up as much as I can but occasionally there are a few stray strands. Really trying to improve this part of my builds!
-
Just like to add that I also tin the stranded wire, I mean some stray strands at the base of where the wire was stripped. Maybe I’m using too small diameter
-
Look in Sluckey’s scrapbook, heat shrink, Doug has info here in this forum, search his tips
-
Look about 3/4 the way down this page
https://el34world.com/Hoffman/instructions.htm
-
There are some subtle points in all this. Doug uses RG174 which is the standard, flexible, and works very well for those with excellent soldering technique. Its inner conductor is robust. RG174's Achilles heel for those of us not so skilled is the inner core insulator, which melts fairly easily and can result in a shorted lead.
RG316, a coax cable type with similar electrical properties to RG174, uses Teflon as the insulator which does not melt at usual soldering temps and thereby avoids this problem. RG316 is stiffer, but I find it easier to use.
-
There are some subtle points in all this. Doug uses RG174 which is the standard, flexible, and works very well for those with excellent soldering technique. Its inner conductor is robust. RG174's Achilles heel for those of us not so skilled is the inner core insulator, which melts fairly easily and can result in a shorted lead.
RG316, a coax cable type with similar electrical properties to RG174, uses Teflon as the insulator which does not melt at usual soldering temps and thereby avoids this problem. RG316 is stiffer, but I find it easier to use.
I've used RG174 in the past and while flexible, it is a little finicky to work with as acheld mentioned. I recently ordered some RG316 based on what I've read in this forum. Never heard of it before but sounded good. I am using it in my current build and am very happy with it so far. The outer jacket is a very thin layer, so it takes a little practice to remove that and not disturb the shield underneath. As acheld said, the inner jacket is teflon so for those us who have the dexterity of a gorilla, it is much less likely to cause a short. So far, I really like it.