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[Amps] 10 KW CCS ON 6M...USING THE 3CX-6000A7... PART 30. Success at Las

Subject: [Amps] 10 KW CCS ON 6M...USING THE 3CX-6000A7... PART 30. Success at Last !!
From: "jim.thom" <>
Date: Tue, 1 Aug 2023 00:09:12 -0700
List-post: <>
OK, the 2  (brand new)  x Ameritron ALS-606's only put out barely 300w on
6m (and only 400w on 75m). Ready to tear our hair out. Plan C was the new
ALS-1306...which actually does work.

Cut to the chase. 10 kw CXR out with aprx 600 w of drive. (brand new
Coaxial dynamics 25-60 mhz, 10 kw calibrated slug). Line section with the
10 kw slug / meter has the pep kit installed. Line section with 1 kw slug,
between ALS-1306 and input to the tube amp....(to measure drive into tube
amp). Line section with 25 watt reflected slug between ALS-1306 and input
to tube amp....(used for tweaking the PI tuned input, with it's 2 x air
variable caps).

Jennings ceramic vac tune cap....and a Swiss made (Comet) ceramic vac load
cap. All testing done on 50.125 mhz.

The big dummy load consist of 32 x 1600 ohm globars (18" long) in parallel
to make the 50 ohm commercial DL. 7-16 Din on output of tube amp and also

B+ sagged quite a bit with a CXR. But with every 1 volt AC going in, he has
aprx 25 vdc coming out. The line sagged 6 vac from the street, so we lost
150 vdc. Then another 125 vdc through the 40 ohm glitch R. No load B+ was
5900 vdc. Loaded to 3.125 amps of DC plate current, it drops to just 4300
vdc. (It would have been 4575 vdc without the above pair of V drops). Then
you have the typ 5-10% drop in the B+ supply anyway. Then the small V drop
across any 2 of the 4 x strings of diodes in the FWB.

On SSB / CW, it drops very little. This is the difference between a static
load....and a dynamic load. Total of 30 uf of filter caps (2 x 60 uf @ 4 kv
oil caps in series), so we don't have a huge amount of energy stored in the
caps. (522 joules).

Plate current = 3.125 amps
Grid current = 500 ma
Loaded B+ = 4300 vdc

DC input = 13,437 watts.
Power output = 10 kilowatts.
Anode Dissipation = 3437 watts.
Eff = 74.4 %

Bias can be toggled between 50 ma idle and 200 ma...(Class AB). (toggle
switch changes the tap on the series diode string, used for bias).

Special thanks to John Lyles, K5PRO, for his assistance on Saturday,
conducting some SRF (self resonance freq) tests on some doorknob caps, on
his Vector impedance meter. (Old HP 500 khz to 108 mhz unit). We changed
out the bypass caps at the cold end of the fil choke.

Scott designed and built the HV supply.  I designed the unique RF deck.
(Scott  also built the RF deck).
The 80-15m 3CX-6000A7 amp will be the next project....already in the works.
I have most of the RF deck designed.

Later.... Jim VE7RF
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