Smallest Dual-6146 HF Transmitter?

[Brian Wood]

You ask a lot! In order to get 100% modulation at the plate, you need to
have the same power level as the transmitted signal, namely 100W. That's why
the DX-100 has such a big modulator, with concomitant big, heavy
transformers. And with tubes, you need high voltage, which usually means big
transformers too.

Here's an idea. Get a DX-100 but get rid of the big heavy case, transformers
and AM modulator. It will be pretty lightweight with all that out of there.
Find a 100W mono or stereo amp intended for home stereos. Use its output to
drive the plate. The DX-100's modulator has an output on the rear panel that
was intended to drive public address systems, and you could feed the signal
in there once you removed the internal modulator. You would need to keep the
modulation xfmr, but it's not nearly as big as the others. Replace the big
bulky power supply with a modern 250W switching power supply such as an
Astec LPS-250, which is lightweight and small (but has gawdawful noisy fans
that you'd want to change). Step it up to the needed 800V with a
transformer.

Hey, it could work...

GL & 73,

Brian, W0DZ

-----Original Message-----
From: Heathkit Owners and Collectors List
[mailto:HEATH at LISTSERV.TEMPE.GOV]On Behalf Of kd4e
Sent: Wednesday, August 22, 2007 7:56 PM
To: HEATH at LISTSERV.TEMPE.GOV
Subject: [HEATH-TEMPE] Smallest Dual-6146 HF Transmitter?


I am looking for a compact dual-6146 transmitter,
preferably 160-10M, or something with a dual-6146
final that I can modify.

It must either be designed to handle AM plate modulation
at 100W or have enough room in the final RF section for
me to modify it.

It must include a power supply suitable to the application.

No industrial size hernia-makers need apply, I need this
to be semi-portable.  (I guess that means an efficient
design on an aluminum chassis.  It's best if the PS is on
a separate chassis.)

Based on what I have learned these past few days it seems
best that I abandon my quest to plate modulate my Heathkit
HW-100.  Sigh.

I will bring my HW-100, & the HP-23b PS/SB-600 Speaker, and
SB-610 scope (the scope is not functioning, may be the crt)
to TARCfest in Tampa this Saturday - to sell or to swap for
what I need.

Sure appreciate all of the wise counsel - I learned a lot!


--

Thanks! & 73, doc, KD4E
Personal: http://bibleseven.com/kd4e.html

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