Hello to the Amps Group.
A couple of weeks ago, I picked up this Clipperton L at a local hamfest.
I really wasn't in the market for an amp, but the price was too good and the
Clipperton L always beckoned me due to it's compact size for a 2KW PEP amp.
Seems
like quite a little powerhouse in a small package. The case was a little
scuffed up, but paintable, and the front panel and meter is pristine.
Well, I wasn't disappointed. The inside was fairly clean, just a thick layer
of dust on the bottles. It has the relay-switched tuned input and the 10m
mod.
I was a little worried that the original Dentron-branded tubes might be
weak, but it does 1200 -1300 watts out on SSB!! WOW !!
I used it this past weekend on the CQ WW DX Contest (SSB) and picked
up a few new countries including some Africans and B1Z (China)!
Anyway, to my questions. The manual gives absolutely NO indication of
HOW to set the ALC, only that it is "negative going, adjustable from rear panel"
I am driving it with a Yaesu FT-101E. Adjusting the pot on the back of the
amp causes the ALC indication on the FT-101E to go from nearly nothing to
lots and lots of action, with the same drive and output. I can put a two
tone input to the transmitter and adjust the ALC until the power starts to
drop off, but my YO-100 scope shows it flat-topping. How do I know when the
ALC pot on the amp is in the correct setting for my transmitter?
Here is a seat-of-the-pants approach that I took:
I drove the transmitter with a two-tone signal from the YO-100, increasing
the drive until just before it started to flat-top. This was somewhere
between 100 and 150 watts out. I did this on 40 meters into a dummy load.
Then with the amp on, I adjusted the the ALC pot to where the ALC on the
FT-101 meter was at the bottom (left ) of the green "good" area.
Does this seem good to you? It still doesn't seem like it has any real
"control" of the transmitter. I can still drive the transmitter harder, and
the output goes up, but the meter goes out of the green "good" area as the two
tone
display on the scope starts to flatten.
I thought that proper ALC should throttle the transmitter power back so that
it would not overdrive the amp. I can't tell that the ALC is actualy
regulating the power out of the transmitter, or just giving the operator an
indication of where it is operating.
Another question is just how hard can this amp work? The book says 1000
watts input 100% duty cycle. Does that mean I can safely run it at 650 or so
mA on RTTY?
On the CW voltage position, I get 1800V no load. Tuned with 60 watts in, the
Voltage drops to
about 1550 V, and the Ip is 650mA, for 1007.5W, (+/- the resolution of the
amp's multimeter).
I get right at 700 watts out into a dummy load.
How much can the power supply provide without burning up?
I saw a post, related to the Clipperton-L, where someone was claiming the
572Bs can run 250 mA each for a total of 1.0 A, and getting 864 watts out.
Now if the plate voltage is at say 1500 volts, (CW position), this would be
1500 watts input. At 864 watts out, that would leave the 4 572Bs dissipating
636 watts,
or 159 watts each. This is within the specified limit of 160 watts plate
dissipation. Can this really do this??? Will the tubes really take this??
Will the power supply handle this???
Can it be used on the high voltage position for morse code for another 2-3 dB
out?
BTW, I fully understand why amplifiers of this era were rated under the old
FCC limit of 1000 W DC INPUT.
And I also know that it is the first 300 - 500 watts that makes the
difference, not the last 300.
At the same time, I don't have another $10dB for a Henry or Alpha. And those
are a lot harder to sneak into the house past the XYL :-)
BUT, I would also like to know what this amplifier is really capable of
doing, safely, without splatter, and without seriously compromising tube
and/or powersupply life.
At the same time, I would also like to see it performing to its full
potential and making as big of a signal as possible, when needed.
After all, isn't that why we use amplifiers?
All thoughts are appreciated.
73 es God Bless,
Rick, WD8JJA.
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