On Sat, 25 Mar 2023 10:33:07 -0700 (PDT), Mike Peace wrote:
On Sunday, April 30, 2000 at 2:00:00 AM UTC-5, John Siegel wrote:
One more suggestion in case you do not already have the tubes. There
are some other versions out there with unusual filament voltages that
may be available cheaper. Some years ago I bought 4 4X150Ds at a
hamfest at an amazingly low price. Most buyers were passing them up
because they have 25.2V filaments instead of 6.3 Since I was building
the amp I saw no problem in choosing the filament transformer to match
the tubes instead of vice-versa. However my amp was for 2 meters so I
can't help with HF amp ideas for these tubes.
John
Bill Fuqua wrote:
At 04:30 AM 4/30/00 -0700, you wrote:
In article <390B919A...@bigfoot.com>, cesn...@bigfoot.com says...
I'm trying to find a schematic for an 80-10m HF amplifier using a pair >> > > >of 4x150a (4cx150a) tubes. An amplifier using these tube should provide me
about 500 watts. Can anyone help.
Chris
NG3F
ng...@bigfoot.com
This is not exactly help, however, look for 'all' the articles for
4CX250 amps. There are hundreds of articles. The 150 is the little
brother of the 250. It is 'plug and play' except that you must run
lower plate and screen voltage.
The 4X150A/7034 tubes are electrically identical to 4CX250B's. They are
even rated for 250 Watts plate dissipation. The plain 4X150A may not be. >> > Look for the /7034 versions. Also, I have found that only about half of my >> > hamfest purchases of these tubes are good. So, make sure you have
plenty on hand when you are ready to fire up the amp. I am taking a
homebrew tester for these tubes to the Dayton Hamvention sense
I will be looking for some more there. Often you can get them for $5 each >> > if their condition
is unknown to the seller which works out to usually to $10 to $15 each for >> > good tubes. If they have any dents in the radiator at all, no matter how small,
don't buy them. Most likely they will have internal shorts. Also, check for the
obvious, cloudy glass around the seal, rattles and discolored radiators. Also,
an ohm meter to check filaments and for shorts is handy.
These tubes life time is very sensitive to filament voltage. DO NOT RUN
6.3 volts on the filament. Keep as close to 6.0 as possible. Or, maybe put in
a relay to drop the filament voltage a bit while in standby. Just a half a >> > volt will make quite a difference in life time. But, on the other hand they
are still
quite cheap.
One more comment, don't consider grounded grid, zero bias operation.
Their grids
will not take it.
good luck
es 73
Bill wa4lav
I'm also looking for a 4CX250 10 thru 80 schematic, Especially hoping
for the Galaxie 2000 schematic that uses (6) 4XCX250 tubes. I like
the idea of using the high grid voltage version 4X150D. Happy for any
reply, Mike
You have replied to a 23-year old thread.
"Mike" may not even be among us now.
You will be better off starting your own thread.
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