Re: Topband: DX-100 adventure - progress

["ZR" <zr@jeremy.mv.com>]

Ive been using a 6AH6 in the VFO and regulating the screen and plate with a 
120V 5W zener and suitable dropping resistor and a 47uF 'lytic with a 
.01disc. Grid drive is still sufficient for 100W+ on 10M with full audio 
after those mods are also done.
A 6AH6 is also the better tube in the VF-1, Johnson 122, Globe Champs and 
others using a 6AU6.
The change to choke input on the LV goes back decades since the original way 
was too much LV for some circuits for long reliability.
I use a scope to get ripple down in all circuits to where I like it since 
most of my customers use them on AM but it shouls also help on CW.
I did make a few contacts in the Stew using a 1939 Meissner Signal Shifter 
at 7W and a 1934 National FB-XA receiver.
Carl
KM1H


----- Original Message ----- 
From: "Charlie Cunningham" <charlie-cunningham@nc.rr.com>
To: "'Bill Cromwell'" <wrcromwell@gmail.com>
Cc: "'top Band'" <topband@contesting.com>
Sent: Saturday, December 21, 2013 12:21 AM
Subject: Re: Topband: DX-100 adventure - progress


> Hi, Bill!
>
> That's great! You're good to go with the elecrolytics, then!
>
> BTW - as for the chirp on the signal - the DX-100 VFO  and voltage 
> regulator
> was pretty much  what they sold separately as the VF-1 vfo. The DX-40 had 
> a
> socket to power it, but I never could get rid of the chirp, until I built 
> a
> separate PS for the VFO. The OA2 gas tube just wasn't stiff enough to
> eliminate the chirp. You might be able to eliminate most of the chirp by
> replacing the gas tube with a Zener Diode. By the time you get up ro a 100
> volts with the Zener, it's really avalanche breakdown and has a pretty 
> stiff
> knee. Might improve your chirp!
>
> Have Fun!
>
> 73,
> Charlie, K4OTV
>
> -----Original Message-----
> From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Bill
> Cromwell
> Sent: Friday, December 20, 2013 11:12 PM
> To: Charlie Cunningham
> Cc: 'top Band'
> Subject: Re: Topband: DX-100 adventure - progress
>
> On 12/20/2013 11:00 PM, Charlie Cunningham wrote:
> > 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
> Hi Charlie,
>
> In the DX-100 there is already a big honking pair of bleeder resistors
> so that the bleeder is divided with one half across each half of the
> series pair. I think that's what you meant. The DX-100 originally had
> two caps rated at 450 volts in series and the bleeder set up that way.
>
> 73,
>
> Bill  KU8H
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