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" <[email protected]>
To: "'Bill Cromwell'" <[email protected]>
Cc: "'top Band'" <[email protected]>
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:[email protected]] 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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