[AMRadio] Ongoing Quest: Legal Limit AM Amp

[Rick Poole]

Just a few thoughts to start the day...

1.  I know that the difference between a DX-100 and the legal limit 
is about 1 "S" unit.  But, an "S" unit is an "S" unit.  I have seen 
plenty of times, although on SSB, where an "S" unit made the 
difference between, say, phone-patch quality (for running traffic for 
boats at sea) and not.  Not that I'm going to be running phone 
patches on AM, just using that as an example.

2.  QSL on the part about using the best antenna... plan is to do 
that and THEN add power.  Current antennas are a 160-meter inverted V 
at 60 feet with open-wire feeders, and a half wave coax-fed 
off-center-fed dipole at 35 feet.  They both work pretty well, but 
the plan is to get both of those up higher, in the spring.

3.  I considered using a commercial pair-of-3-500's amp like the 
SB-220 or TL-922, but the ones I've looked at appear to be too 
power-supply limited to get true legal limit especially on AM.  I 
have a TL-922A and get 1200 watts PEP out of it at best, on 
SSB.  Yes, I know that there is no measurable difference between 1200 
and 1500 but per (1) above, if I can't get at least X4 amplification 
(1 "S" unit) then it's not worth doing.  Anyway, nothing I can buy 
for less than around a thousand bucks is likely to be very happy 
running on AM for very long.  Now, a Chippewa... :-)

4.  I don't "have to ask for a schematic to build one of the simplest 
pieces of ham gear" but it has been more than 40 years since the last 
time I home-brewed a high-power amp (or much of anything else, for 
that matter), so if an article was available on the web that 
describes a reasonable design AND perhaps offered suggestions on 
where to get the necessary parts, that would be very helpful.

5.  I'm acutely aware of the dangers of high voltage.  I'm currently 
restoring a 30L-1 including rebuilding its power supply, and I'm 
comfortable that I know what I'm doing and will still be here when it's done.

Rick WA1RKT