Johnson Invader Transmitter

[Brian Carling]

On 16 Nov 97 at 17:36,  Rod, N5HV wrote in the TEMPE BOATANCHORS
LIST:

> Can anyone tell me something about the Johnson Invader transmitter?
> Tubes, modes, size & weight, reputation?

Rod, and the group,

The Johnson Invader is primarily designed as an SSB transmitter.
It will also do AM at reduced power.

It must have been introducedd around 1960-63 I would guess.
Not in their 1958 listings in the ARRL Handbook anyway!

A look in QST for Sept, 1961 produces an E.F> Johnson ad for the
Invader (pp 88-89)

200 watts INPUT on SSB/CW and 90 watts on AM.
VFO built-in. Sold new for $619.00 which was a LOT of money back
then! (LIke about $2,000 today I would guess!)

They don't say in the ad what tubes it used, but I bet someone here
can tell us. I would guess that they used a pair of 6146s but I could
be wrong.

The July 1961 QST has a much more detailed TWO PAGE ad for the
Invader with many special features listed, such as the VFO heater
being on all the time, even when the rig is turned off, so that you
have zero warm-up drift! (Pages 90-91) but they STILL don't tell
which tubes they are using!

HOWEVER!!! I fnd a REVIEW of the Invader on Page 44 of the JUly 1961
QST Magazine!!

It uses oodles of tubes (about 20) including FOUR in the power supply
section alone! The final RF amp does indeed use a pair of 6146-s.

IT's a crystal filter type rig, and was widely regarded as the
transmitter of choice in its day. OF course Collins soon shot them
out of the water by coming out with their S-line transmitter which
was more compact and had many great features also. The 75-S1 must
have been out around the early 60s also.

Other tubes in the Invader:  6U8 12AU7, 6AH6, 12AT7, 6CX8, 12BY7
Driver, 6T8, 6AL5, OA2, 5R4, 5U4, 6X4 etc.

The rig includes VOX, and runs on 80, 40, 20, 15 and 10m.
It uses a PI-Network output, and boasts a claimed harmonic
suppression of 60 dB.

Perhaps some of the other fellers on this group can tell you more
about their actual experiences operating the Invader. I have never
used one, and have only seen them occasionally when they show up at
hamfests, which seems to be rare!

It looks to me like they were not all that popular due to thepricing
and the thin wallets of many young hams back then (grin!)


73 to all

Bry, AF4K





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*** 73 from Radio AF4K/G3XLQ Gaithersburg, MD USA  *
**  E-mail to:  bry at mnsinc.com                     *
*** ICQ: 3910641  ***
**  http://www.mnsinc.com/bry/                     *
****************************************************
AM International #1024, TENTEN #13582. GRID FM19. Using a SWAN 250 on 6m,
Other rigs: Valiant, DX-60/HG-10, FT-840, TM-261, Ameco TX-62, Gonset Communicator III
HTX-202...TEN-TEN #13582, DXCC #17,763 Bicentennial WAS

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