Hi folks.
Tom W8IJ says regarding HV-power supply voltage drops.
<It is very typical to have less than 10% sag
<when a properly designed and constructed capacitor input supply is
<operated off a normal residential power line.
Well,,I'm not a technical guru so the only thing I can do is to
look in ARRL handbooks (or similar) and read transformer manufacturers
specs. Also I look at the factory amps folks are using in there shacks.
Not often, or more right to say never have I seen an amp with less than
10 percent voltage drop. My friends AL1200 has more, and he is not able
to get full US legal limit because to less drive, So he does'nt suck
maximum current. (Yea,, I know some of it has to do with some drop of
voltage from the house power line)
More typical in real life is that amps PS drops abt. 15-20 percent.
What do you say folks out there, do you look at your HV meters??
Tom also say:
<It would be much simpler and less expensive to find out what is wrong
<with your conventional capacitor input supplies and correct that,
before
<going into the unnecessary expense and design headaches of a choke
<supply. A choke input supply is ONLY necessary when you have power
mains
<supply problems you can't correct without using a low power factor
load.
I'm using my homebuilt choke PS, I still don't feel any headaches.
The reason for my choke is to "cut off" the not needed high level of
high voltage during no load condition. The choke and its bleeders does
that perfectly, so my sag therefore looks less at full load. This trick
give me the pleasure of more RF output because I can run more HV to the
tube without risking an internal ARC in the tube during no load.
Dear Tom, in my case its all about RF power, NOT power mains problem.
As long as I belong to those poor guys with +10 percent sag in my
various "conventional" HV supplys I'll stick to my choke.
One time I saw and tested a Henry 4K Ultra. Wow,, keydown and HV dropped
from 4200 to 3800V. Output was way way more than legal US limit.
Very impessing to me, I tought,what's the magic with this power supply ?
Sure thing it had an choke. Moreover I study the schematics of Henry
8K Ultra. 3phase 220v and export models 3phase 380v, they all have
choke power supplys. Collins commercials from the 60's have all chokes
incl. the 30S-1.
Tom also says,
<If you have a varying load current, choke design is critical!! I hope
<you find a VERY good choke designer for your custom choke so you don't
<need to purchase three or four chokes just to find one that works.
Well, the designers at Henry radio must then be VERY good !
I belive this is the scheme, the use of choke power supply is to costly
for todays Ham radio amplifier manufacturer. More parts, more weight
etc.
Manufacturers gives us products capable of all the power we need (right)
anyway without any costly chokes.
73's Hakan
--
FAQ on WWW: http://www.contesting.com/ampfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
Sponsored by: Akorn Access, Inc. & N4VJ / K4AAA
|