This is probably the page you're looking for:
http://www.nj7p.org/Tube4.php
Jeff, KC2OBG
From: Steve Wedge
To: drakelist@zerobeat.net
Sent: Wednesday, September 21, 2011 8:59 PM
Subject: [Drakelist] Tube data online
I can't seem to get to the root page,
Hi Guys,
Am I cursed here, or what...?!
After literally weeks of flawless, dependable service, the PTO in my Drake T-4X
transmitter has returned to its good ol' wobbly self again (SIGH!). It started
last night---thinking that maybe the PTO signal was being affected by something
external to it,
And as Garey has reminded me many times:
"We do this for fun, right?"
73,
Al, W8UT
www.boatanchors.org
www.hammarlund.info
"There is nothing -- absolutely nothing -- half so much
worth doing as simply messing about in boats"
Ratty, to Mole
On 9/22/2011 2:01 PM, Eddy Swynar wrote:
*/Hi Guys,/*
Eddy -
The cap that was the problem in Steve's PTO was C145, which is the main resonating cap for the
variable inductor. This is the long, brown or silver tubular cap on the bottom of the board. The
schematic is marked 85 pF, but Steve's was coded as 90 pF and measured 92.5 pF. C143 and C14
Steve -
Your PTO is on the way back. I finally got the time to pack and ship it. It's been sitting on the
bench, running for the last week or so with the counter on it. It stays within +/- 100 Hz from day
to day, just sitting in the open. I turned the counter so I could see it from my desk
Hello all,
Were those trimmer caps the work of the team of ladies assembling and
testing the PTOs? Could it be that they started with the main resonating
cap and then added those trimmers as needed to get the PTO dead on?
Kris KM2KM
- Original Message -
From: "Garey Barrell"
To:
Hi Garey,
Originally---in my T-4X---I replaced C89 (3000 pfd.) with two 1500 pfd. s.m.
caps in parallel. The white tubular cap that I was referring to at 33 pfd.
is---I think!---either C86, or C87 on the T-4X schematic, both of which are
(unfortunately) simply marked with an asterisk therein...
Kris -
There is no trimmer cap in the original PTOs. There are small, selected NP0 caps used to trim the
main resonating cap. I suspect a tubular NP0 was less expensive than a 'decent' quality trimmer,
eliminated the possibility of a 'golden screwdriver' attack, and long term stability of fix
Hi Guys,
For a look-see at the suspect tubular capacitor that I am referring to in my
T-4X PTO, go to this website:
http://www.wb4hfn.com/DRAKE/DrakeArticles/TechTips/PTO-Repair.htm
Scroll down half the page to where you see the heading "ELECTRICAL FAILURES":
the photograph with the arrowed
Eddy -
OK. That's what I call 'Version 4' (of 17) variation of the PTO. The cap I replaced on Steve's,
(same version, just different component designators,) was C88, which is the main resonating cap.
C89 is a DC block, and would have little to no effect on the stability of the oscillator, un
Yes, that is a 'trim' cap and should be less than 10 pF or so. It's not likely to have much effect
on the stability of the oscillator. More likely are the caps on the 'other' side of the board,
shown further down, the two brown tubular caps to the left of the Diode D13 are 45 pF each. That's
Did ICM make crystals for Drake, since Drake did not make their own?
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Search for numerchron tymeter. Suitable replacements occasionally come up on
ebay. You may have to buy a desk clock and get the part out.
Kihwal, K9SUL
On Sep 6, 2011, at 10:56 AM, Hunter Ellington wrote:
> As long as we are on the C4, is there a source for a replacement digital
> clock?
There is of the numerchron (or what ever the correct name is) timers on ebay
right now (search under Drake).
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