MA-18-1(?)

[Chuck Penson]

Got this message from a fellow looking for details on the solid state
replacements for the tubes in Heath VTVMs.  If anyone can help him out
please respond directly to him.

Many thanks!

Chuck / WA7ZZE



--------- Begin forwarded message ----------
From: "John H. Gibson" <gibson at alma.edu>

I remember when Heath sold solid-state replacements for the vacuum tubes
in their VTVMs. I believe the part number was IMA-18-1(?), but I do know
that
these solid-state replacements appeared at the same time that the IM-18
VTVM came on to the market.

I have several old Heathkit VTVMs and would like to install solid state
replacements for the tubes in at least a couple of them. Do you know what
was inside
the two components of the IMA-18-1? I assume a pair of FETs for the 12AU7
replacement, and a pair of diodes for the 6AL5 replacement, but I would
like details.

One other question: Have you seen a good circuit for a battery
replacement for the VTVM? I assume I can do something with a 317 voltage
regulator, but I am
curious to know what others have done.

Merry Christmas and 73
John Gibson
Office phone: (517) 463-7187
Secretary: (517) 463-7198
Office FAX: (517) 463-7076
Home phone: (517) 463-3632
e-mail: gibson at alma.edu

--------- End forwarded message ----------

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