[Amps] Amplifier for 630 meter band

Merv Schweigert k9fd at flex.com
Fri Nov 10 13:01:03 EST 2017


Lot of work for naught..   the power limit on 630M is 5 watts and even 
with a very poor antenna
you only need 100 to 200 watts to get 5 out of the antenna.   A single 
or two MOSFET amplifier
will do that no problem and will fit in a mini-box.

NO3M has converted a SB-1000 think it was,  he used it under his 
experimental license which has
higher power limits.   Google NO3M and there are pictures or some info.
There are a couple others on line that converted tube amps. Almost none 
use them now.
MOSFET amps are doing 80 to 90 percent efficiency,  why waste a tube amp 
at 50 to 60
percent.
No high voltage,  no fans,  much better ways to go these days, 
especially on 630M

73 Merv K9FD/KH6



> "U may well have a tough time  stuffing parts into a SB-200 chassis.  This is where a simple, bigger box would help out.  Something like a  single  3-400Z /  3-500Z would do the trick, dead simple.  Then u could also stuff a 4-400 A / B /C in there as well."
>
> Yes, it may make sense to pull some of the larger tuning and LP filtering components into a separate case, outside the SB-200 case.  One nice thing about VLF is that tolerances are very loose for things like lead lengths.  Just be sure that wires carrying high voltages are very well insulated.
>
> I'm certainly open to having a second case with the additional filtering components. That second case won't have a power supply or tubes needing cooling, which simplifies things greatly.
>
> I'm not dead set on starting with an SB-200 by any means. If a junk 3-500Z or 4-400 amp drops into my lap, I could just as readily run with that. I will check out NEARFEST on the spring and see what turns up.
>
> If anyone in New England reads this and thinks they may have a suitable amp for sale (no tubes is fine, burned bandswitch is fine, power supply must be good, price must reflect condition; looking for a low-priced junker amp for extensive modifications), please reach out to me directly.
>
> 73,
> Cathy
> N5WVR
> <n5wvr at arrl.net>
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