[Collins] Test
kirklandb at sympatico.ca
kirklandb at sympatico.ca
Wed Apr 8 23:00:33 EDT 2009
I believe Dennis has an unfair advantage ..... his wife use to assemble the 30L-1's.
Well, its not really unfair.
> From: jefferis at antelecom.net
> To: g369n849j at weather.net
> Date: Wed, 8 Apr 2009 18:55:01 -0700
> CC: Collins at mailman.qth.net
> Subject: Re: [Collins] Test
>
> Greetings all,
>
> A nice tutorial thread! Ah, yes, the 30L-1 power switch replacement
> challenge. Not easy. About a year ago Mr. Dennis Brothers told me me
> how he does it. I have notes from the telephone conversation, but I am
> not sure I can articulate it in writing well enough to be worthwhile,
> even though I think I can do it now, if forced to. He described the
> power switch replacement as the "most difficult repair to do on a
> 30L-1". I believe I read a recent post indicating that he is a CRA
> guest speaker at Dayton this year. If someone going to Dayton could
> corner him and get a good description of the procedure, IMO, it would
> be a great subject for the "Journal".
>
> Bob, KF6BC
>
> Brian - I am glad to hear you have things under control now.
>
> Bob, KF6BC
> On Apr 8, 2009, at 4:44 PM, Dr. Gerald N. Johnson wrote:
>
> > On Wed, 2009-04-08 at 09:06 -0700, Brian Harris wrote:
> >> The bridge I am talking about is the one that is used for tuning the
> >> plate tank, not the DC metering. This bridge is supposed to be a
> >> factory aligned thing that you don't touch but I know it's off
> >> because
> >> when I adjusted the amplifier according to the manual, the plate
> >> tune/load settings were not optimal. I think I will determine the
> >> optimum plate/load setting for each band and then attempt to tune the
> >> two bridge controls (an R and a C) so that the meter indication is
> >> correct but not before surfing the web to see if someone has a better
> >> way of doing it.
> >>
> >> {the manual I have shows an adjustment technique}
> >>
> >> Brian Harris phone 214-763-5977 email cosmophone at yahoo.com website
> >> www.myhamshack.com/wa5uek
> >>
> >> --- On Wed, 4/8/09, Dr. Gerald N. Johnson <geraldj at storm.weather.net>
> >> wrote:
> >>
> >> From: Dr. Gerald N. Johnson <geraldj at storm.weather.net>
> >> Subject: Re: [Collins] Test
> >> To: "Brian Harris" <cosmophone at yahoo.com>
> >> Date: Wednesday, April 8, 2009, 10:43 AM
> >>
> >> On Wed, 2009-04-08 at 08:00 -0700, Brian Harris wrote:
> >>
> >>
> >>> Most definitely the list is working.
> >>>
> >>> {But only when I use a different address than the one I'm
> >> subscribed
> >>> with.}
> >>>
> >>> I have been working on the 30L-1 with the weird output tank
> >> behavior
> >>> and found the problem yesterday. A terminal on the
> >> bandswitch that
> >>> shorts the various tank coil sections as you progress from
> >> 80 to 10
> >>> meters was cracked to the point of no continuity. This lack
> >> of
> >>> shorting is what I figured the problem was but I expected
> >> the culprit
> >>> to be one of burned contacts rather than a broken terminal.
> >> Anyway,
> >>> because of this, as you went up in frequency, you always had
> >> the
> >>> entire tank coil present although the loading capacitance
> >> decreased in
> >>> large steps as it should.
> >>>
> >>> {That sure explains the tuning you saw.}
> >>>
> >>> In addition to this easy fix and the missing T/R relay,
> >> there were
> >>> other problems the previous owner left me (some people
> >> should just not
> >>> work on electronic equipment). The three screws that hold
> >> the
> >>> aluminum panel that divides the RF section from the power
> >> supply to
> >>> the inner rear panel were missing along with two of the four
> >> 1/4" tall
> >>> metal standoffs that hold the loading capacitor away from
> >> the front
> >>> panel. By the way, you cannot remove the front panel on a
> >> 30L-1.
> >>> It's spot welded to the aforementioned divider panel.
> >> Perhaps that's
> >>> why nobody ever responded to my question about its
> >> removal...either
> >>> how to or you can't. To remove the bandswitch you have to
> >> back it out
> >>> after you have removed the tubes and various other things
> >> that are in
> >>> the way. By the way, the reason the bandswitch terminal was
> >> broken is
> >>> because the former owner mishandled it as he/she took it out
> >> so he/she
> >>> could replace the On/Off switch. This person apparently
> >> failed
> >>> Soldering 101 as they did a lousy job of replacing the
> >> switch also.
> >>>
> >>> {There is that unfortunate characteristic amongst some
> >> Collins
> >>> collectors.}
> >>>
> >>> Today I will reinstall the tubes, replace the missing
> >> standoffs and
> >>> see how it performs after I align the tuned input circuits.
> >> I am
> >>> fairly certain the metering bridge circuit needs tweaking.
> >> I don't
> >>> know of a procedure for doing this but I'll figure one
> >> out.
> >>>
> >>> {Last time I did that to a Dentron, I unhooked a wire here
> >> or there
> >>> and inserted my "standard" meter for current. Voltage was
> >> easier, and
> >>> the resistors had all drifted. You could check them with a
> >> good
> >>> ohmmeter and simply replace them all with 1% film resistors
> >> and have
> >>> confidence in the metering.}
> >>>
> >>> P.S. As a newly retired (laid off Nov 2) EE with a
> >> background in RF,
> >>> Analog, Digital and Software Design, I really enjoy posts
> >> from you and
> >>> a few others on the list that are also technically strong.
> >>>
> >>> 73,
> >>>
> >>> Brian Harris, WA5UEK
> >>>
> >>> email cosmophone at yahoo.com
> >>> website www.myhamshack.com/wa5uek
> >>>
> >>> --- On Wed, 4/8/09, Dr. Gerald N. Johnson
> >> <geraldj at storm.weather.net>
> >>> wrote:
> >>>
> >>> From: Dr. Gerald N. Johnson
> >> <geraldj at storm.weather.net>
> >>> Subject: [Collins] Test
> >>> To: collins at mailman.qth.net
> >>> Date: Wednesday, April 8, 2009, 9:15 AM
> >>>
> >>> CQ CQ is this list working?
> >>>
> >>> --
> >>> 73, Jerry, K0CQ, Technical Advisor to the CRA
> >>> All content copyright Dr. Gerald N. Johnson,
> >> electrical
> >>> engineer
> >>>
> >>>
> >>
> >> ______________________________________________________________
> >>> Collins mailing list
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> >>> Help: http://mailman.qth.net/mmfaq.htm
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> >>>
> >>> This list hosted by: http://www.qsl.net
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> >>> http://www.qsl.net/donate.html
> >>>
> >>>
> >> I'm an EE because I was a ham first. I started out at a time
> >> when
> >> everything was tubes, but in college power was tubes, small
> >> signal was
> >> germanium transistors, ICs hadn't yet been invented. I worked
> >> at Collins
> >> my first job with BSEE in broadcast, very high power with
> >> people who did
> >> the ham gear earlier. I didn't worship Art and didn't
> >> appreciate his
> >> treatment of hired slaves and took a leave of absence for
> >> graduate
> >> school and haven't been back.
> >> --
> >> 73, Jerry, K0CQ, Technical Advisor to the CRA
> >> All content copyright Dr. Gerald N. Johnson, electrical
> >> engineer
> >>
> >>
> >>
> > I have downloaded 30l-1-_5th-ed-06-02-sec4.pdf. In section 4.7 it
> > describes how to set the capacitor.
> >
> > What this is is a pair of volt meters, one on the filament for the
> > input
> > voltage, and one on the plate through the plate to grid capacitances
> > (as
> > described in section 3.8). The voltmeters have opposite polarity and
> > so
> > when the voltages seen by the diodes are the same (taking into account
> > the voltage dividers on both) the meter shows zero and the stage
> > gain is
> > as designed. If the plate load Z is off a little as you run the
> > drive up
> > the PA will clip and that will show on the meter. If the PA isn't
> > resonant, the voltage gain will be low. If the loading isn't right the
> > gain voltage will be off.
> >
> > ______________________________________________________________
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> >
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>
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