[R-390] Below 8mhz problem.
Jim Temple
[email protected]
Tue, 22 Jan 2002 20:37:43 -0500
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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