[Milsurplus] Some microphone and handset test data

[jhaynes@alumni.uark.edu]

H-33()/PT handset for radio has a 7 wire cord and a U-161 connector.
Is the U-77 connector any different?  They seem to be interchangeable.

H-156/U handset for telephone? has a 4 wire cord and same connector as
above.  Won't key the radio transmitter.  But if the radio has pins
B-E-H of the connector grounded, then open the connector and move red
wire from E to F and the handset will then work with the radio.

H-156/U uses a TA-117/PT carbon microphone element, which appears to
be interchangeable with the Western Electric T1 element used in 500-style
telephones.

a TA-117/PT undated has a resistance of 60-75K ohms.
a TA-117/PT Audiosears dated Dec 75 has a resistance of 3.5K ohms.
a TA-117/PT Audiosears dated Jun 83 has a resistance of 500 ohms.
a T1 Western Electric dated 51-84 has a resistance of 600-1000 ohms.
two new T1 elements from Mike Sandman have resistances of 300-500 ohms.

So it appears the correct resistance for a T1 element or a TA-117/PT is
in the range of 300-1000 ohms, and anything much more than this is bad.

Mike Sandman sells an electret replacement for the T1.  I haven't yet
got any listening test reports, but installed in a H-156/U handset it
makes the SSB transmitter output kick up at least as well as a carbon
T1.  Presumably it should sound better and last forever.

The H-33()/PT handset uses a different carbon element.  Anybody know where
to get replacements for these?  One I have is a Roanwell, dated 2-53,
and is pretty close to a dead short.

A T-32 mike retrofitted with a Western Electric F1 element (used in the
older F-series handsets, as on the 302 style telephones) dated 5/43
has a resistance of 150-170 ohms.  I'll have to dig out some more F1
elements to see how typical this is; but of course all the extant F1
elements are likely to be old.