The PHILCO Phorum
Signal generator test leads - Printable Version

+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Various and Sundry Categories (https://philcoradio.com/phorum/forumdisplay.php?fid=37)
+--- Forum: Test Equipment (https://philcoradio.com/phorum/forumdisplay.php?fid=31)
+--- Thread: Signal generator test leads (/showthread.php?tid=24333)


Signal generator test leads - patmat2350 - 05-11-2023

Sorry for the newbie question... I've been searching and have not yet achieved enlightenment... or maybe this is so basic no one talks about it?

But I have a new signal generator in one hand and a tube radio in the other, and they need connecting.
I understand that at a minimum I need to put a capacitor in line with the "hot" lead to avoid toasting the signal generator.
Fine, but what's a good way to do this?

- I doubt that a string of alligator clips and caps flopping around on the workbench is right.
- Could make up a lead with a cap soldered in, but the idea of a solid-lead cap with no strain reliefs flopping around in a cable doesn't sound right either.
- And if this is SOP, wouldn't there be ready-made test leads for this? Not finding any...

RE: Signal generator test leads - klondike98 - 05-11-2023

Depending on the radio and the band being aligned there are different cap values called for in alignment instructions. Don’t know how much difference it can make however. I just use the alligator clip approach.

RE: Signal generator test leads - patmat2350 - 05-11-2023

As long as you touch the right place, maybe little importance. Slip and touch B+, that won't do the generator any good!

I may need to learn about alignment, for starts I just want to inject signals ..

RE: Signal generator test leads - DaleHCook - 05-11-2023

klondike98 Wrote:I just use the alligator clip approach.

So do I, but have made my own with very short leads and booted small clips for such purposes.

RE: Signal generator test leads - patmat2350 - 05-11-2023

For the record, here's the advice from Elements of Radio Servicing (1947):

   

462ron - 462ron - 05-12-2023

Pat, I’m using an old Heathkit SG-8 that was my dad’s. I reworked it by replacing the original connectors on the front of the cabinet with BNC type which is more compatible with newer test leads. While doing that, I inserted a cap to the center pin or hot side so it’s always there and I don’t need to worry about cobbling together anything before connecting to a radio. If I remember, I think I used a .01 mfd/630 volt unit. Works great on anything I’ve used it on so far!

Ron

RE: Signal generator test leads - DaleHCook - 05-12-2023

462ron Wrote:I’m using an old Heathkit SG-8 that was my dad’s. I reworked it by replacing the original connectors on the front of the cabinet ...

About 40 years ago I used a number of pieces of vacuum-tube EICO and Conar test equipment that my father built from kits in the '60s when I was young. I eventually replaced almost all of them with GR and Heathkit instruments, but still use two of them (EICO 625 emission tester and 950A LCR bridge) - the rest are shelf queens. Some of them used the 2-conductor button mic jacks that were so common on EICO and Heathkit equipment in the '60s. I never replaced any of those jacks because 40 years ago parts jobbers were still common all over the country and I could get those plugs easily and cheaply for making custom cables.

RE: Signal generator test leads - RodB - 05-12-2023

I use the loosely coupled approach. I feed the generator signal to a coil of wire through a .1mfd cap. Then move the coil close to the radio to get the correct signal strength. When I have to inject the signal I use a .05mfd cap with an alligator clip soldered to a lead.