Ron-
Your suggestion sounds very credible due to the fact that my problem
worsens as I cycle the relay more (add more heat in coil) plus creating heat in
PA area. Thank you!!
Byron.
----- Original Message -----
From: [EMAIL PROTECTED]
To: [EMAIL PROTECTED] ; [EMAIL PROTECTED]
Cc: Garey Barrell
Sent: Tuesday, April 29, 2008 3:49 PM
Subject: Re: [drakelist] TR-4 TX Hang-Up
I saw once where the relay iron core was expanding do to the heat the coil
generated around it, which to this point is normal. But in this case as the
core expanded it shorted against a bare coil winding. The core itself being
at ground potential, when shorted against the coil winding provided the ground
path to key the relay. Once the relay was unkeyed by removing power, it
cooled, and worked again as normal until it heated up again. So don't put
aside the possibility of a heat related problem in the relay itself.
Ron / WB4HFN
-------------- Original message --------------
From: Garey Barrell <[EMAIL PROTECTED]>
>
> Garey Barrell made an utterance to the drakelist gang
> ----------------------------------------------------------------------
> Byron -
>
> OK. Relays take more coil current to "pull in" than they do to "hold
> in". It takes a certain amount of current through the coil (pull) to
> drag the armature from it's non-energized position to the energized
> position. It takes much less current to (hold) it once there, so slight
> leakage might NOT be sufficient to pull, but more than enough to hold.
>
> I don't know of any good way to touch up the panels. The original
> "paint" is so thin, (I actually think it is more a dye (anodize?) than
> paint, but don't know for sure,) and as a result any sort of paint ends
> up looking worse than the mark! For a small mark or two, it might be
> possible to just "fill" the mark to the level of the panel, but a string
> of numbers would be a real challenge. Never could understand people
> that do that sort of thing, especially on the front panel!!
>
> I just saw your order. There are scans of both the 34-NB and the 34-PNB
> manuals, with quite a bit of information, plus I have added a photograph
> of the board itself with active components and alignment info
> annotated. There is also a Voltage table for the NB, which has not been
> previously published. It's really a straightforward design, and most
> units in the field benefit from an alignment.
>
> A lot of the components are common between the TR-3 and TR-4, but every
> once in a while they threw in a curve like that cap to keep us off
> balance! :-)
> < BR>> Your CDs will go out tomorrow. Thank you!
>
> 73, Garey - K4OAH
> Glen Allen, VA
>
> Drake 2-B, 4-B, C-Line & TR-4/C Service Supplement CDs
>
>
>
>
> Byron Tatum wrote:
> >
> > "Byron Tatum" made an utterance to the drakelist gang
> > ----------------------------------------------------------------------
> > Hey Garey-
> > Thank you for the comments and help. I start nights at work and
> > will have several to complete, then I will get back into the TR-4. I
> > will measure voltage as you suggest, looking for a slight voltage
> > drop. Then I will check out relay itself.
> > I am beginning to think that it is the magnetizing of pole piece
> > and relay wear that is the problem. If it was a leakage to ground on
> > the 6EV7 pin #1 lead you might think the set wo uld go into TX on its
> > own (relay energize) every now and then, of which I have never saw it
do.
> > One other thing- I bought a nice TR-4 from a fellow, based on
> > several pictures, but the photo angles, due to glare, covered up (of
> > all things) a ham's DL # engraved on the front panel in tiny lettering
> > , immediately to the right of "TR-4" on front panel. Do you know of a
> > touch up paint that matches the darker grey of that front panel area?
> > I got the set for a decent price, it was nice and had the built in
> > NB, but had a problem (as advertised). I found T-9 to be burned out in
> > center area of coil form. I had a spare T-9 from a parts unit TR-3.
> > Thank goodness I opened up the TR-3 T-9 transformer before I installed
> > it -- it had a 56 pF cap in it that was not in the TR-4 T-9. Otherwise
> > the coils looked the same. Anyway, I clipp ed out the capacitor and all
> > went OK after the repair. That is not a fun repair for sure!!
> > CUL, Byron.
> > ----- Original Message ----- From: "Garey Barrell"
> > To:
> > Sent: Tuesday, April 29, 2008 1:46 PM
> > Subject: Re: [drakelist] TR-4 TX Hang-Up
> >
> >
> >> Byron -
> >>
> >> Well things were going well until you pulled the tube out of the
> >> socket! :-)
> >>
> >> There are a limited number of possibilities in that case. The relay
> >> coil leads go through the feedthrough bypass caps _under_ the power
> >> connector. Of course the relay lead to the 6EV7 is the one UNDER the
> >> Jones connector, the last one in the "arc" of feedthroughs there.
> >> (C92) There are no more components between this feedthrough and t he
> >> 6EV7 tube socket. The other relay coil lead goes directly the +250V
bus
> >> via the next feedthrough cap along the arc, (C91). So the voltage
> >> measured at the tube socket pin with the tube out should be exactly
the
> >> same as the +250V bus. Any drop would indicate leakage. See attached
> >> photo from my CD (at reduced resolution).
> >>
> >> So..... Leaky C92, leaky tube socket, pinched wire. One possibility I
> >> have seen a few times is the "down" stop on the relay gets hammered
down
> >> over the years, allowing the armature to actually touch the pole piece
> >> of the coil. The pole piece is slightly magnetized, and if the
armature
> >> physically is in contact with it, it will "stick". An easy check is to
> >> slip a piece of paper in to prevent metal to metal contact between the
> >> two. The " down" stop can be bent back up to prevent this contact.
> >>
> >> Let us know what you find!!
> >>
> >> 73, Garey - K4OAH
> >> Glen Allen, VA
> >>
> >> Drake 2-B, 4-B, C-Line & TR-4/C Service Supplement CDs
> >>
> >>
> >>
> >>
> >> Byron Tatum wrote:
> >>> Hello-
> >>> I have an unusual problem perhaps someone could shed some light on:
> >>> I have a TR-4 in 29K serial range that functions normally
> >>> except it will not go back into receive, until after approx 30 second
> >>> delay, after the mic button is released or the function switch turned
> >>> back to "SSB". This condition worsens (longer delay) the more you
> >>> frequently you transmit. The sidetone disappears but T-R relay will
> >>> not release.
> >>> I have tried different known-good 6EV7 tubes, have replaced a lot
> >>> of the coupling / bypass caps in T-R circuits, did resistance /
> >>> voltage checks, adjusted the VOX / VOX delay controls, tried other
> >>> tubes in T-R circuit, etc. to no avail.
> >>> What is real curious about this is that while waiting for it to go
> >>> back into receive and T-R relay is engaged, IF YOU PULL THE 6EV7 FROM
> >>> ITS SOCKET THE T-R RELAY STILL DOES NOT RELEASE. I suspect the issue
> >>> is with the lead that goes from T-R relay coil to pin #1 on 6EV7
> >>> (somehow allowing enough leakage to ground?) or could it be the T-R
> >>> relay coil itself?? I made sure socket / pins and all are clean on
> >>> 6EV7.
> >>> Any help appreciated, thanks.
> >>> Perpl exed,
> >>> Byron WA5THJ.
> >>>
> >>
> >
> >
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