On 11/2/25 06:03, Bob D. wrote:
Nice job.
Please correct me if I'm wrong. I'm an old fart but novice amp constructor.
If amp is to be used strictly with a modern exciter that employs
"pre-distortion", I can do away with a lot of filter capacitance. Then no
need for soft start and glitch protection, if needed at all, will not need
to be as stout.
Considering for my 6m amp project using a gs35b. Also, plan to use metal
film caps in the supply. Very low ESR, self healing, don't dry out, and are
becoming competitive with electrolytic caps, thanks to electric vehicles
use.
As a retired broadcast engineer I don't understand the brute force kind
of power filter used in many power supplies. Most huge amplifiers that
must not contained detectable hum component use the "high pass" kind of
"filter network" DC power filter. Aided with a six phase rectifier an
oil filled 4.µFd capacitor (at 50. k Volts) is all that is used.
At 3.6 k Volts (@ ≈.7 Ampere) two 10. µFd at 4. k Volts with an inductor
(filter choke) between them resulted in no detectable hum in the 1 kW
(peak of sync) NTSC output using oil filled capacitors.
The important aspect of this kind of power supply is when there is a
tube arc there is not enough energy stored to cause permanent tube damage.
A 2. kW Tetrode cost over $4,000. (UHF TV translators)
--
Ron W4BIN - Understanding is much better than
knowing how.
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