Anyone been successful in building an amplifier at 6 meters? I have a
couple and was thinking about trying it.

Doug N4IJ

Should work just fine. I haven't done it, but I do have a 4-400 and am
thinking about just what you propose.

See:
http://www.g8wrb.org/data/Eimac/4-400A.pdf

Scott
N0EDV

SNOWDEN wrote:
Anyone been successful in building an amplifier at 6 meters? I have a
couple and was thinking about trying it.

Doug N4IJ

On Tue, 12 Sep 2006 23:16:20 GMT, "SNOWDEN"
wrote:

Anyone been successful in building an amplifier at 6 meters? I have a
couple and was thinking about trying it.

I've not seen a 4-400 amp on six,, but they are rated to 110 MHz and
the book shows just shy of the legal limit out at 75 MHz.

I don't know how difficult the'd be to neutralize.
Sounds like fun and I think they'd be a better tube for six than
3-400s or 3-500s.

Good luck,


Doug N4IJ


Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

Roger (K8RI) wrote:
On Tue, 12 Sep 2006 23:16:20 GMT, "SNOWDEN"
wrote:

Anyone been successful in building an amplifier at 6 meters? I have a
couple and was thinking about trying it.

I've not seen a 4-400 amp on six,, but they are rated to 110 MHz and
the book shows just shy of the legal limit out at 75 MHz.

I don't know how difficult the'd be to neutralize.
Sounds like fun and I think they'd be a better tube for six than
3-400s or 3-500s.
=====================================
Up to the mid 1970s type 4-400 transmitting valves (tubes) were used in
the UK in Band 1 (approx 45-65 MHz )TV transmitters.
For a 7 kWatts area transmitter there were 7 chassis of 2 valves each.
So they should be excellent for the 50 MHz amateur band.

A very early design can be found in QST March 1967 ,pages 11 - 15.
Titled : Six-Meter Kilowatt with 4-400As or4-125As.

The design involves 2 valves (tubes) in push-pull config.

Although push pull RF Power Amps are nowadays no longer or not
frequently used , I feel it is still interesting reading and might give
some ideas for a homebrew amplifier.

If you can't find the article , I can send you a scanned copy of the 5
pages.

To email me remove the obvious chars from the above address.

Frank GM0CSZ / KN6WH

On Wed, 13 Sep 2006 13:09:43 +0100, Highland Ham
wrote:

Roger (K8RI) wrote:
On Tue, 12 Sep 2006 23:16:20 GMT, "SNOWDEN"
wrote:

Anyone been successful in building an amplifier at 6 meters? I have a
couple and was thinking about trying it.

I've not seen a 4-400 amp on six,, but they are rated to 110 MHz and
the book shows just shy of the legal limit out at 75 MHz.

I don't know how difficult the'd be to neutralize.
Sounds like fun and I think they'd be a better tube for six than
3-400s or 3-500s.
=====================================
Up to the mid 1970s type 4-400 transmitting valves (tubes) were used in
the UK in Band 1 (approx 45-65 MHz )TV transmitters.
For a 7 kWatts area transmitter there were 7 chassis of 2 valves each.
So they should be excellent for the 50 MHz amateur band.

A very early design can be found in QST March 1967 ,pages 11 - 15.
Titled : Six-Meter Kilowatt with 4-400As or4-125As.

The design involves 2 valves (tubes) in push-pull config.

Although push pull RF Power Amps are nowadays no longer or not
frequently used , I feel it is still interesting reading and might give
some ideas for a homebrew amplifier.


Many years ago, there was an article in QST (I think) that used a pair
of 6C21 radar pulse modulators in Push pull with copper pipe for a
tank circuit. I don't remember what they used for a link but I think
it was just a u-shaped piece of smaller tubing.

That thing would put out today's legal limit with a sneeze. Even more
if you turned the driver on.

Unfortunately 6C21s are big (bout 16" tall), difficult to find, and
expensive. I used to pay $5 USD each.

If you can't find the article , I can send you a scanned copy of the 5
pages.

To email me remove the obvious chars from the above address.

Frank GM0CSZ / KN6WH
Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

Doug:

It was the wide use of these tubes (along with others like the 4-250 and
4-1000) in the TV and FM broadcasting industry that made them so plentiful
and allowed "used pulls" to be so readily available to hams. Amp designs
using them have been around for decades. I just looked in the 1965 ARRL
handbook and they have a 4-250 amp for 6 meters. A little homework should
turn up many more.

Good luck,

Roger K6XQ

Hi Doug,

I could load a diagram for an amplifier in the files or photos section of
the yahoo rfamplifiers group if you'd like. Post a want over on the group
and we'll help where possible. No problem putting a 4-400 on 50 MHz.

http://groups.yahoo.com/group/rfamplifiers/

cheers,
skipp


: SNOWDEN wrote:
: Anyone been successful in building an amplifier at 6 meters? I have a
: couple and was thinking about trying it.
: Doug N4IJ