Topband: DX-100 adventure - progress

[Charlie Cunningham]

BTW, Biii - tip/suggestion  - for those series-connected electrolytics you
probably should put a pair of equal value resistors - one across each series
capacitor, as the leakage currents will not be equal in each capacitor in
each series string and the DC voltage won't divide equally across each
capacitor unless you put individual "bleeder" or "swamping" resistors across
each cap in the series pair to equalize the DC across each capacitor in the
series!  I'll be interested to see how it turns out! I never had a DX-100
"Benton Harbor Kilowatt"!  I did  have a DX-40 for a while, but no 160 on
that one, though! I do have an EF Johnson Navigator in pretty good condition
that needs to  have all of its electrolytics replaced because of their age.
I does have 160 (and 11 meters also!).

Good luck and Merry Christmas!

73,
Charlie, K4OTV

-----Original Message-----
From: Topband [mailto:topband-bounces at contesting.com] On Behalf Of Bill
Cromwell
Sent: Friday, December 20, 2013 10:27 PM
To: 'top Band'
Subject: Topband: DX-100 adventure - progress

Hi,

Recently I posted about my DX-100 and an effort to get it usable in time 
for the Stew Perry. I have made progress and it looks like I'll have it 
ready to use in time and never mind about the holidays, the holiday mail 
overload, etc.

I successfully recapped and tested the "low voltage" supply and changed 
the circuit to choke input. I like doing that and some other hams 
suggested doing it, too. So I did. The VFO and RF stages - excluding the 
finals - sound very good on 160 through 40 meters. No chirp shows up at 
all until I get to 20 meters and there is barely enough chirp to notice 
if I pay attention. 15 meters and, finally, 10 meters there is 
noticeable chirp and some drift. I didn't really let it warm up well 
before I tried those higher bands. I was more interested in the 160 
meter operation since that is the immediate goal.

I had to order new caps for the high voltage final amp plate supply. I 
thought I had suitable caps but mine would have given me only 50 uF with 
a pair in series. That is NOT enough. I am afraid the new caps will not 
arrive with enough bench time left to make it for the Stew. So I doubled 
down on the caps I already have. I built two banks of caps with two caps 
each. Each set is a series pair of course and the two sets of caps are 
in parallel to give the needed 100 uF at 900 volt rating. The center 
connections of the two banks are also connected in parallel so that the 
bleeder sees them as *ONE* pair of caps in series. The thing is built on 
a pair of terminal strips with reinforced connection points to 
accommodate the bleeder and switch wiring that was already in the 
transmitter. I have it completely fabricated AND mounted in the DX-100. 
This weekend I'll get to wire it and test it. Hopefully it will be ready 
to operate. I'll be cleaning up some other messy wiring that previous 
owners left in there and then put all the screws back in place. A little 
DeOxit on a few more controls and then the smoke test.

And then... CQ de KU8H.

If the caps don't work out for some reason I can hope the new ones 
arrive in time. I started taking pictures so maybe I'll finally do some 
on-line show n tell when I'm done.

73,

Bill  KU8H  aka  Santa Claus
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