[Boatanchors] DX-100 adventure - progress

[Rob Atkinson]

I don't know much about the DX100 but with a choke input filter, 50
mfd filter cap seems like way more than enough and 100 seems dangerous
frankly.  Maybe not to you but to components in the rig.  Is that the
stock value?   Every time you key the h.v. that thing charges and
stresses the components--the choke and plate iron secondary.   I used
to think if a little C is good more is better until stuff caught on
fire hi hi.   if the choke is around 10 H you can probably do okay
with 20 mfd.

73

Rob
K5UJ

On Fri, Dec 20, 2013 at 9:27 PM, Bill Cromwell <wrcromwell at gmail.com> wrote:
> 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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