[Johnson] Attenuator, connectors for Thunderbolt

[Glen Zook]

The bias plug on the Thunderbolt is the same "layout"
as the Motorola, General Electric, etc., microphones. 
However, the diameter of the insulation on the plug is
sometimes too large to fit the connector on the
Thunderbolt (I have worked on two Thunderbolts for
customers in the last month).  I had to find the
remains of an old microphone that had a thin
insulation on the plug and then cut and file it down
to where it would fit.

NEVER run a Thunderbolt (don't even turn it on!)
without the bias plug being inserted and an external
relay connected properly to switch the bias between
standby and transmit.  Both modes require a bias, it
is just a different amount.

As for the antenna relay connection on a lot of the
Johnson transmitters (the HC6/U type), I do
manufacture reproduction ones of these.  Click the
zcomco URL at the end of this message for more
details.

As for the filter capacitors:  The oil filled seldom
go bad.  But, if they are the dry versions and if the
rig hasn't been used for a while, they are definitely
suspect.  You may have to change them out.

Glen, K9STH


--- Mahlon Haunschild <mahlonhaunschild@cox.net>
wrote:
 
For the bias connector, you can use the four-pin
insert from the Amphenol microphone plug used on
gazillions of Motorola 2-way (Motrac, et al)
microphones.  The "proper" connector uses this exact
same insert, but with a small backshell.


=====
Glen, K9STH

Web sites

http://home.attbi.com/~k9sth
http://home.attbi.com/~zcomco

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