I would leave that Clipperton V alone, and preserve what's left of it.
It's a pretty rare bird these days. If I didn't live so far from you
(only 800 miles or so), I'd buy it from you just to restore it, as
poorly as it may have operated when new.
Back in the olden days around WWII-vintage or so, iron transformer
windows were generally considered good for roughly 100 VA CCS per square
inch of window area. My dad had a Xerox copy of a NBS circular
describing transformer design; I still have my copy somewhere. Through
the years, I've found that to still be a reasonable way to guess at an
unknown transformer's possible capability, based upon transformer iron
formulations of that time period. Remember: that's CCS, not ICAS.
I've run Heathkit HP24 power supplies at 600W CW output over weekend
contests, keeping the transformer cool simply by placing a small muffin
fan over the top of the cage. Otherwise, they run hot enough during a
contest that you can't touch them.
Steve, K0XP
On 3/7/2024 3:06 PM, wb0gaz via Amps wrote:
Had a few helpful off-list replies - in a nutshell, the KVA of the
transformer remains unknown.
The HV secondary of the "V"'s transformer is probably about 800V (so through a
doubler gets you to the 2200-2250V plate voltage.
I had initially thought of a GI7B russian tube (have some, and sockets) on 6M,
however, the 2200-2250V plate supply would starve the tube (2500V seems like a
better fit) and augmenting the HV transformer (either by boosting the 220V
primary up by 10% or so, or adding 100V or so to the secondary winding) might
(or might not) work based on whatever is in my walk-in junkbox.
So, I much appreciate the off-list replies, however, the HV supply voltage
would be a problem and the current capability of the transformer in the
envisioned application is unknown.
73 Dave WB0GAZwb0gaz@yahoo.com
On Thursday, March 7, 2024 at 02:45:05 PM MST,<wb0gaz@yahoo.com> wrote:
Follow-up to my original post (trying to assess the utility of the
Clipperton V's power transformer) ---
I found an internal photo of a Dentron Clipperton L amplifier in a youtube
video (URL below.)
https://www.youtube.com/watch?v=HViv6rBtTvw
While the transformer appears to be the same overall size (at least comparing picture of
transformer vs. cabinet with with my amplifier's transformer vs. cabinet width), the
schematic of the Clipperton L shows a low- and high-voltage tap on it's power transformer
(and the rectifier/doubler board has eight electrolytics populated; this amplifier's
rectifier/filter board appears to be the same PCB but only six electrolytics populated.)
Also, the "L" has filament and control voltage windings, but lacks the bias and
screen supply windings of the Clipperton V's transformer.
On Thursday, March 7, 2024 at 01:35:11 PM MST,<wb0gaz@yahoo.com> wrote:
I've got a Dentron Clipperton V (2M 500W single 4CX250) amplifier, purchased
used some years back (when shipping was cheaper!).
It looks like it's in clean but not pristine condition.
I've never used it, and my fixed-station circumstances somewhat discourage tube
QRO on VHF.
From everything I've read (and just looking inside at the "RF Deck" design),
I'm inclined to agree with commentary that it's not a very effective RF design for 2M
(lumped output tank elements, open frame T/R relay, etc., as if it was designed by
someone that hadn't looked at VHF amplifier designs of the same era.)
So, I'm interested in whether the amplifier (cabinet, metering, power supply, cooling
path, etc.) could be re-purposed, by cleaning up the power supply (replace components in
the HV rectifier/voltage doubler circuit) and replacing the "RF Deck" (but with
what, not decided.)
About the power transformer - what is done with this in terms of a project is
dependent on the power transformer (assuming it's not dead, which I'd verify)
capability as much as anything else.
In the spirit of "look before leap", I'm eyeballing the power transformer (which in the
manual is just "power transformer" with no other spec.) It has two primary windings (so
115/230V primary), a HV secondary winding that uses a voltage doubler to generate the (claimed)
2250V plate voltage, and several auxiliary windings (filament, 12V control, negative V for grid
bias, positive V for screen voltage.)
The transformer's core dimensions (excluding the windings) are 3-1/2" x 5-1/4" x
4-1/4".
By comparison, my Dentron GLA-1000B's power transformer (same, excluding the windings) are
3" x 3-1/4" x 4".
Comparing the cubic inch volume of the two transformer cores yields that the
Clipperton-V is about 1.8 times that of the GLA-1000B's power transformer
(whose only duty other than HV appears to be four sweep tube 6.3V filaments, so
it has a bit more work to do there.)
Given that a GLA-1000B can deliver 500-600 watts (including whatever drive
power passes through, maybe 75-100 watts), would comparing core volume (above)
be a reasonable way to estimate the power transformer power thru capability?
Thanks for any comments, observations, or (if you're in Colorado) a plea to
rescue the amplifier!
73 Dave WB0GAZwb0gaz@yahoo.com
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