Yeah, those old "Benton Harbor Kilowatts" did a pretty good job on AM - not
quite as good as a Viking II or a Viking Ranger, but pretty good. Those old
1625 modulators and a real high-level plate-modulation transformer did a
pretty good job. When you consider what we had to pay for one, it enabled a
lot of us, except for poor kids like me that had to build things on old
junked broadcast receiver chassis from whatever junk and WW II surplus we
could scrounge up. BUT we had fun and we learned a lot -back in the old days
!! I still have fun!
73,
Charlie,K4OTV (licensed 1957)
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Tom W8JI
Sent: Wednesday, January 08, 2014 8:06 PM
To: Bill Cromwell; topband@contesting.com
Subject: Re: Topband: DX-100 adventure contiunued
> So far I haven't found the line voltage lower than 125 Volts and in early
> afternoon it was at 130 volts. The transmitter was working and no problem
> with the finals at all before I did the recap. I did the power supply
> recap in all three power supplies because the low voltage supply was
> getting really hot. I'm not sure what the high voltage was before the
> recap so it may not be all that much higher now.
DX100's run high on high voltage because the filter choke does not have
enough inductance for the bleeder current. It does not reach "critical
inductance" until the PA is drawing nearly full current.
> Two or three hams have mentioned the neutralizing circuit for the finals.
> I would have suspected that too. But - the DX-100 doesn't have a
> neutralizing circuit!
That's correct. It does not have neutralization. I added it in mine, but it
isn't problematic without it if you stay off 10 and 15 meters.
> A few hams have suggested that the DX-100 is just a piece of junk anyway.
It certainly wasn't the best rig, but it is generally fixable and a great
learning platform. Even with the bandwidth and other issues, it works OK
below 20 meters for old boatanchor use like AM.
73 tom
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