[R-390] Below 8mhz problem.
James Miller
[email protected]
Tue, 22 Jan 2002 21:06:17 -0500
Go to Chuck Rippel's 390 page, he discusses the variable IF and
troubleshooting. The "below 8 mhz loss" appears to be a common problem,
possibly a failure in first variable IF. Check the miniature coax
connectors at the top of the RF module. I believe the first mixer
oscillator is injected through one of those connectors. Here's the web
site for further reading:
http://www.r390a.com/VARIF.htm
Jim Temple wrote:
>
> Hi Roger,
>
> I have found that E209 before the 1st mixer V202 has a voltage of -.85 in
> standby. The other RF deck points are up to spec's. This indicates to me
> that something before the 1st mixer is bad.
>
> I will check all the coils, switchs, rotary contacts, and whatever plugs in,
> and thouroughly clean and inspect. When finished, I will get back to you
> and the list.
>
> Thanks for the suggestions, everyone!
>
> Regards,
>
> Jim
>
> ----- Original Message -----
> From: "Roger L Ruszkowski" <[email protected]>
> To: <[email protected]>
> Sent: Tuesday, January 22, 2002 7:53 PM
> Subject: Re: [R-390] Below 8mhz problem.
>
> >
> > Jim,
> >
> > More than one problem here.
> > So what did you expect?
> >
> > The receiver will not hear the signal generator at all, so I have not
> been
> > able to align the variable IF's.
> >
> > No signals but the Cal tones are killers.
> >
> > It sounds like an oxidized contact point in the antenna relay. As its from
> > the massacre
> > you will likely find some crud in the box.
> >
> > Do some ohm meter checks on the antenna relay Pin inside on
> > Mini BNC to pin in triax connector . Pin to pin should give
> > continuity and pin to ground should be open.
> >
> > Do you hear the antenna relay click as you go into cal mode and
> > out of cal mode to mgc?
> >
> > Strap the break-in pin on the back terminal board to ground.
> > Operate the break-in switch off and on.
> > Do you hear the relay in the audio deck click and kill the audio hiss?
> > Do you hear the antenna relay click?
> >
> > If a the relay is clicking and a couple operations do not clear it.
> > It will open up and can be fixed. Some course paper ("newsprint")
> > can be used to clean the contacts. Rain condensation has likely
> > dirtied the contacts.
> >
> > Get a very good small Philips screw driver and really lean into it as you
> > take the very small screws out of the cover plate on the relay and
> > look into the contact cavity. (dead spider or what ever in there).
> >
> > Poor performance under 8.
> > is .5 - 1, 2-3 and 4-7 all equally bad?
> >
> > Look into the first mixer tube socket for crud.
> > Look into the fist mixer Z cans for crud.
> > Again likely just weather oxidation in a contact.
> > Look at the RF band switch for crud.
> > Likely you will pull a can off its contacts, open it up
> > and put it back down and every thing will work no
> > trouble found The normal experience.
> >
> >
> >
> >
> >
> > Pull it all apart and clean the contacts (De Oxit preferred)
> > Use what ever you have but
> > 1.) do not ever tell this mail reflector you did it.
> > 2.) If what you use causes other problems always infer
> > the trouble came with the receiver and was not self inflected.
> >
> > Work over the antenna relay and get some signals coming through.
> >
> > Read the manual. Read Chuck Ripples web pages.
> > Down load and read the handbook.
> >
> > As this was one of those receivers you will want to one day
> > pull the every deck. pull all the tubes and all the RF deck cans
> > and give every contact a cleaning.
> >
> > On the first IF .5 - 8 Mhz.
> > Again, just because its been outside, you may find a cap
> > in the RF cans to be shorted. These will come apart and
> > can be cleaned up. The little rubber disk between the
> > cap sections gets stiff. Read Chucks and Dave Medley's
> > R390/A and R390 web sight maintenance tips. The adjustment
> > caps are in the RF and crystal decks and share a common
> > problem. Do not take down any you do not have to. If and only
> > if it is shown to be the problem. Aggravation exceeds return on
> investment.
> >
> > Then go read the books again,
> > Get all the stuff you need to treat the items correctly.
> > Then go read the books again.
> > Acquire a large rewarding stock of choice beverage.
> > Do not start celebrating prior to completion of the task.
> > Then just jump in and do it.
> > Do not be intimidated.
> > If it goes wrong stop and ask.
> > It may take an hour or two to get mail back at 0 dark thirty
> > But some one will gladly talk you through it.
> > When its all done, just let your self go and revel in it.
> >
> > While your at it you will want to give the gear train a good bath.
> > a 32 to 40 hour ordeal is about typical.
> >
> > Your only going to do it once and your only have to do it
> > because some fool let those fine receivers set out over
> > winter in the weather.
> >
> > A good semi PM could get done on the depot bench in 4 hours.
> > 8 hours was average for a tech his first year out of school.
> > (to do it all and do it right)
> > So 16 hours your first few times around is ok.
> >
> > Roger KC6TRU
> >
> >
> >
> >
> >
> > "Jim Temple"
> > <[email protected] To:
> <[email protected]>
> > ville.edu> cc:
> > Sent by: Subject: [R-390]
> Below 8mhz problem.
> > [email protected]
> > h.net
> >
> >
> > 01/22/2002 02:58 PM
> >
> >
> >
> >
> >
> >
> >
> > Hello to the group,
> >
> > I recently bought a "massacre" R-390 and completely tore it down and
> > cleaned
> > and replaced all the "problem" caps.
> >
> > I have already replaced the 100pF cap at T-207 with no luck.
> >
> > The problem I have is that the calibrator is strong and loud on all bands
> > 8mhz and above, and below 8mhz is barely audible and extremely faint.
> >
> > The receiver will not hear the signal generator at all, so I have not
> been
> > able to align the variable IF's.
> >
> > The fixed IF hears fine, but the signal is injected directly into the IF
> > module. With the variable IF's, the signal can not be heard while input
> > into
> > the balanced antenna input.
> >
> > Perhaps a kind soul has experience with the problem described and will
> > offer
> > some hints as to a possible fix.
> >
> > Thanks.
> >
> > Jim Temple
> > Louisville, KY.
> > 73, KF4ICZ
> >
> >
> > _______________________________________________
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> >
> >
> >
> >
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>
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