View Full Version : What leads should be used with old Heathkit tube voltmeter?


Thyratron
08-27-2008, 12:58 AM
I wasn't quite sure on which board I should ask this, but since I think these meters still get some fair use in old TV work, I'll try here. Recently I found a Heathkit V-7A in nice shape (and with the added bonus of a Mullard 12AU7 in it), but missing its leads. This is the one that has the banana-plug sockets for the common and AC connections, and the 1/4 inch "headphone" socket for the DC. Can I just use any everyday leads, or do I need something in particular? Also, what type of lead should be used in the (unusual) DC jack?

Tube TV
08-27-2008, 06:20 AM
If im correct yours would have originally has 2 different test leads .
Later on they put the a switch in the probe so that you could select the 1 meg resistor for measuring DC voltages .
Mine is the model newer , made about 1962 .
looks like this one
http://www.heathkit-museum.com/test/images/im-11.jpg
Personally , I did not like the switching type probe , and I prefer the 2 inividal main probes .
I found that the switching one was fat , and was not all that easy to get into tight spaces . , and somtime the switch gets bumped
You can use a regular probe for the DC measurement but you need the 1 meg resistor in it .
Once you get them all fixed up the Heathkit VTVM's are really a great instument , and are one of the most handy items on the bench .

Please note , If you make a DC lead , be sure that you put the 1 MEG resistor at the probe tip , not at the plug end as this will cause you to have false DC readings .

I think I have some probe & lead , wiring info , I'll post in up tommarow ...

Tube TV
08-29-2008, 04:36 AM
Found this site .....
Thought you might enjoy it .


http://www.heathkit-museum.com/test/hvmv-7a.shtml