[Heathkit] For Sale - Heathkit Seneca Model VHF-1 Xmtr

[Glen Zook]

The VHF-1 Seneca actually is a VFO controlled
transmitter with provisions for crystal control.  It
uses 6146 or 6146A tubes in the final amplifier stage
(I definitely do not recommend trying the 6146B in
this particular transmitter).  The missing octal tube
is probably the rectifier.  I have something sitting
on top of my Seneca right now so I can't see just
which tube this is.  However, everything except the
driver, finals, and rectifiers are miniature tubes.

As for worth, depends on the condition.  I have seen
some rough ones go for well under $50.  Ones in
excellent condition up to $150 to $200.  Just depends
on the condition and how bad someone wants it!

I use mine with an external VXO to drive a varactor
tripler for 432 MHz CW.

When crystal controlled the Seneca makes a very good
CW transmitter.  But, when controlled from the VFO it
"chirps" to "high heaven"!  For AM the VFO is stable
enough for most operation.  The transmitter does use
"controlled carrier" modulation.  This is a form of
clamp tube modulation in which the output power of the
transmitter varies with modulation.  Same modulation
was used in the DX-35, DX-40, DX-60, and Cheyenne
(MT-1) mobile transmitters.  Johnson also used
controlled carrier modulation in a few rigs.

The 4 wires sticking up from the bandswitch into the
final amplifier section are used for neutralization.

Usually, the two longer ones are for 6 meters and the
two shorter ones for 2 meters.  Because of the
frequency difference you do have to neutralize the rig
separately on each band.  

Anyway, the Seneca was "top dog" in its day on 6 and 2
meter AM.  I have had mine since 1966.

Glen, K9STH


--- Bob Kocisko <k6pf@ix.netcom.com> wrote:

Not sure what it's worth.

=====
Glen, K9STH

Web sites

http://home.comcast.net/~k9sth
http://home.comcast.net/~zcomco

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