4-400 ideas?
Ron Harshbarger
build an HF amp. How about some ideas on the best circuit? Maybe some
references to published plans.
73
K3PID Ron
Richard Drabble
It uses 4-400 valves (ok toobs if you wish) and seems a good design.
73
Richard G1SLE
Ron Harshbarger wrote in message ...
Marty
Ron Harshbarger wrote:
>
> I have a pair of 4-400 tubes with sockets and chimneys. I would like to
> build an HF amp. How about some ideas on the best circuit? Maybe some
> references to published plans.
>
> 73
> K3PID Ron
I've built a grounded grid amplifier based upon the an ARRL Handbook
circuit shown for a pair of 3-500's and later substituted 4-400's with
the grids tied together. It worked quite well with an output only a bit
less than I was getting from the 3-500's previously used.
Marty K1FHR
BOB DUCKWORTH
grids. Use swamp resistor so max output on the TX you plan to use
will not exceed linear region of grid swing. Bias tube(s) as per data
sheet. You can do this for parallel or push-pull depending on what
sort of tank you want to mess with. You can use air wound tranny
if you only want one band.
-bob
Kf8od
Eimac news letters or Radio Handbook by William Orr
Long live QRO!
CommQuart
Only ham amp I remember using the 4-400 tubes
was the rare Heath Chippewa (sp?).
Peter
Richard Drabble wrote in message <7du5se$ven$1...@news7.svr.pol.co.uk>...
>Try looking at the cct. for Kenwoods TL-922
>It uses 4-400 valves (ok toobs if you wish) and seems a good design.
>73
>Richard G1SLE
>
>Ron Harshbarger wrote in message ...
Skip May
: I have a pair of 4-400 tubes with sockets and chimneys. I would like to
: build an HF amp. How about some ideas on the best circuit? Maybe some
: references to published plans.
: 73
: K3PID Ron
Hi Ron,
I was laughing so hard at "Bobs answer" that I almost forgot to come
back... He's trying to sound like he's an amp expert, but it comes off
like he's a CB amp/hack guy...
First, 4-400's are great tubes, lots of gain... I would find a late 70
through early 80's ARRL Handbook where a grounded grid construction
article is printed. This seems to be the most popular method for hams to
use these in newer projects.
They operate similar to 3-500z, but require the additional grid to be
dealt with, in g-grid operation, both are often tied to DC/RF ground.
This is refered to as triode operation of a tetrode. The cathode is driven
through a tuned input for best linearity. They provide less gain in gg
operation vs a pair of 3-500z.
Onward...
In true tetrode operation, they drive with much less power. Early 60's
ARRL Handbooks are great places to look for the 4-400 in tetrode
operation.
Very similar circuits using 4-125 and 4-250 are pretty much the same
tube circuit, with lower plate diss. These tubes are "little brothers" of
the 4-400. Common high gain tetrode operation, requires considerable care
in construction to avoid forced neutralization requirements (feedback
problems). Often this type of circuit is grid driven. Some designs allow
more broadband operation (without tuned input).
Most common ham tranceivers have enough drive to allow grounded grid,
triode operation of a 4-400
hope that helps....
skipp
PS, the Kenwood TL-922 used 3-500z tubes, not 4-400's as mentioned by
another Author.
Also stop by Rich Measures, AG6K's web page for amplifier information.
VE6NAP
CommQuart <comm...@erols.com> wrote in article
<7e35mu$nv0$1...@autumn.news.rcn.net>...
> I thought the 922 used 3-500Z tubes.
> Only ham amp I remember using the 4-400 tubes
> was the rare Heath Chippewa (sp?).
>
> Peter
Also the list should also include
Johnson ThunderBolt ,
Adams model 1010 Linear Amp (1956)
and a good number of ARRL handbook amps...
>
J. Andy Thompson
grid grounded. Works great! Most any amp with 3-500's can use the
4-400's if you ground the screen grid with the others. Being a
broadcaster, I have access to 4-400's, so I use them.
4-1000's also work in place of 3-1000's if you ground the extra grid.
That's my next project, since I have several of them.
Andy
W7CXA
Woody White
pix is on my web site listed below. Have 2 .jpg images
(160K & 190K) which are schematics of the PS and the rf
deck. Can attach to email if you like....Built years ago
before my documentation was as "clean and computerized"
(translate cad) as now.
Woody
--
----------- de Woody, WB4QXE -----------
Ham Homebrew/ATV Circuits -*- Scanning Electron
Microscope Images
13w...@gmail.com
Me to. Broadcaster, I mean. Am 64. Working on my last station, and first TV.
I'm writing to you asking how well will a pair of 4-400's in parallel do in at 76-82 MHz? I'm thinking 500 watts modulated with 8vsb, atsc. Need 1.20 kW. Four 4-400 in parallel? .....
Why Am I Building Such A Thing? I need to replace the amps that came with our transmitter.
I paid slightly less than the price of a space shuttle for our DTV transmitter. Modulator, encoders, combiner and mask filter work great.
The four power amps, 300 watts each, use three MRF-151G's each. Each MRF-151G runs at 40 volts 5.0 amps.
SWR's 1:1.04.
Transistors don't wear out?
These do. At 40 volts & 5.0 amps, they don't short, they don't open, but twelve new MRF-151G's make power for about eight months. Drive them harder ? They make power .....for about an hour till they blow up.
Cooling ? If this type-accepted, type approved transmitter wasn't bolted to the floor, it would hover!
I know solid state xmtrs
are used by nearly all stations. I don't think you can buy one that's other than all solid state. Had no trouble with the Harris (Gates Air) 5kw solid state AM, but the MW5 was also trouble free. (Have an MW-1 parked in my barn if
someone needs one).
So, your opinion please. Senile? or can I solve this cronic problem with four 4-400's?
Oh! Almost forgot! I found a way to get vastly improved tube life from 4-400's. Ever since I bought a station, they last up to 300% longer than when I was CE....
Joe Jurkenas
WEXZ-LD
Bangor, ME
13w...@gmail.com