[R-390] R390-A questions

Thu Jul 27 17:19:55 EDT 2006

I agree with all you guys are saying but if I had just dropped (guessing) 
$1200 to $1500 buck for a pro rebuild I would box it back up and have the 
rebuilder deal with the problems and pay the shipping back.  I know that 
puts the radio at risk again because of the shipping issue but that's what I 
would do....unless of course the owner is capable and equipped to get into 
the gear train etc....

It may require dropping of the front panel and who knows what.....why go 
through all of that when you just paid good money to have the radio gone 
through and it develops a problem like this right after delivery.

It may turn out to be a broken gear clamp which will require 
replacement....it just gets deeper and deeper.

Bob have you talked with the restorer about the problem?

I've been on both sides of these type issues having done restorations for 
payment on R-1051's and a few R-390 series radio's.  It's no fun but I would 
expect to have to make it right if I were the guy that just got paid good 
money....

Cecil...

----- Original Message ----- 
From: <n4buq at knology.net>
To: <r-390 at mailman.qth.net>
Sent: Thursday, July 27, 2006 3:28 PM
Subject: Re: [R-390] R390-A questions

> If you are lucky enough to get the "driven" gear back onto the wide gear 
> in
> the same tooth as it was when the radio was last aligned, then you should
> be okay; if not, you will probably have to do an alignment (or keep trying
> to get the original teeth meshed).
>
> If things have slipped enough, you may have to do a mechanical alignment 
> as
> well to ensure the cams are where they are supposed to be in relationship
> with each other.  It depends on which gear slipped as to whether this 
> might
> be necessary.
>
> I'm not trying to scare you, but want you to know what all might have to 
> be
> done to get the radio back to operating as it should.  You can do all of
> this, but you might have to ask some more questions and feel free to do 
> so.
>
> Barry - N4BUQ
>
> On Thu, 27 Jul 2006 15:43:58 EDT, Flowertime01 at wmconnect.com wrote :
>
>> Bob,
>>
>> The problem you describe here reads like a RF band switch alignment
> problem.
>>
>> You also describe a split gear slip problem. I though Barry did a nice
> job
>> responding to that problem for you.
>>
>> The spring in the split gears need not be maxed out to get the job done.
> A
>> wimpy spring or a missing spring in a split gear is not a show stopper.
> Get
>> enough tension on the springs by rotating one of the gears against the
> springs in
>> the gears to get some tension on the springs. then go a bit more or less
> until
>> the teeth on both gears line up. Then you need to slide the gear on or
> off
>> the shaft until the split gear runs against the wide gear and both sides
> of the
>> split gear stay engaged in wide gear and the tension remains on the split
>> gears from the split gear springs.
>>
>> The idea of the split gears is to remove some of the gear lash when you
>> change directions when tuning up and down in frequency. Too much tension
> and the
>> whole gear train give you R390 wrist. Too little tension and the springs
> start
>> to fall out.
>>
>> The minimum tension is longer gear life and you can live with a little
> lash
>> in the gear train when tuning. Nothing sacred in the gear train set. Play
> with
>> the clamps, alignment and adjustments until you get a feel for working
> with
>> them and getting them to run in line and smooth. If you brake a clamp ask
> here
>> on the reflector for a part. someone will make you a reasonable offer to
> cover
>> postage and aggravation of getting it in the mail.
>>
>> -------
>> But now the first two bands do not work correctly unless the megacycle
> change
>> knob is tuned lower than the click stop (or whatever you call it).
>>
>> -----
>> This stop would be the detent.
>>
>> The Rf band switch changes from 999. to 1.000
>> at 1.000 to 1.999
>> at 2.000 to 3.999
>> at 4.000 to 7.999
>> at 8.000 to 15.999
>> at 16.00 to 31.999
>>
>> We would call these the RF band octaves. There is one set of RF
> transformers
>> and a slug rack for each of these band octives in the Rf deck..
>>
>> You can set the Rf band switch with a meter as described in the manual. I
> do
>> not recommend this operation. As you tune up and down the band and change
>> octaves the RF band switch changes. Some gears take care of this. You can
> read
>> about it in the manuals.
>>
>> Do you have a copy of the Y2K manual from the Net?
>>
>> The RF band switch changes as needed. It should seat the switch wafers in
>> their centers when the detent on the MC knob hits the center seat. You
> can adjust
>> the detent spring in or out for more or less tension. Again less tension
> is
>> good. But enough so the MC knob set still when the KC knob is spun.
>>
>> If you have to go past the MC change point and then back up to get the RF
>> band switch to set up and enable an octave for you, the switch is out of
>> alignment.
>>
>> The RF band switch alignment is independent of the cam alignment, Zero
> adjust
>> and KC band over run alignments. You can do the RF band switch alignment
> and
>> then do the other alignments without going back to the RF band switch.
>>
>> A real little bit. Just enough to be a pain.
>>
>> The best way to set the RF band switch is to pull the RF deck and adjust
> the
>> band switch shaft by eye ball. Worry not about pulling the RF deck. Read
> the
>> manual a bit. Find a long #1 Philips screw driver to reach the green
> screws
>> behind the RF deck. Find a couple 2x4 blocks to rest the frame on. These
> leave
>> the front panel hanging in free air. Thus you can drop the front panel on
> to the
>> bench and pull the RF deck.
>>
>> Some Fellows like to stand the stand the receiver on the RF deck end and
>> remove the front panel. It then swings like a door at the bottom of the
> receiver.
>> You can get at the Dial lock, Oldham coupler spring on the KC shaft, BFO
> pitch
>> and bandwidth switch shafts.
>>
>>
>> The RF band switch is a 6 position 6 section switch. Some of the switch
>> sections carry B+. Not all sections line up real good. Look at the
> schematic and
>> find the switch sections that have B+ on them. You want this switch wafer
> to
>> align the best.
>>
>> Do not try to change the wafer contacts or rotate the wafer sections.
>>
>> Remember, yesterday this receiver worked today it does not work.
> Something
>> simple fell apart and some simple action will put it back together. The
> effort
>> to get to that simple loose part has nothing to do with the total
> problem. The
>> effort to get the receiver back together after fixing the simple problem
> has
>> nothing to do with the problem. All that extra exercise is just a slow
> screw
>> job and real work takes real time.
>>
>> After years the switch sections do not all fully mesh and align real good
> on
>> each wafer and each contact. If you just do an alignment by meter without
>> looking at the switch you can get a working receiver. But you risk having
> a wafer
>> section where the contacts just bearly make contact. Over time this just
>> bearly there contact will burn. If you look at your receiver you may see
> a contact
>> that has been burnt from a prior alignment that was just barely making 
>> it.
>>
>> Its a judgment call for best looks. Tune the receiver up through the
> bands
>> and down through the bands. Look and see how all the wafer sections look
> at each
>> change point. Loosen the clamp on the band switch and adjust it a little.
> Run
>> up and down the bands until the switch looks to get the best alignment
> you
>> can get. You want the Rf band switch to fully make at each change point
> tuning
>> both up the band and down the band.
>>
>> -----
>> The feel of the knob is definitely not  right especially when I go from 1
> to
>> 2 megacycles, there are two distinct clicks.
>>
>> ---
>> Bob, you are right on here. One click is the RF band switch moving. The
> other
>> is the detent hitting center. They should both occur at the same location
> of
>> the MC knob. OK like closer than your receiver does so the RF band
> switches
>> clean without cranking the knob both directions.
>>
>>
>> ----------------
>>  A few of the other bands also sometimes need to be fooled with
>> (megacycle change knob rocked back and forth etc.) to come in right. It
>> seems to me that the space where the springs are in between the two gears
>> comes too close together at a certain point and this is when the spring
>> falls out. Does this indicate worn parts? Also is this a major
> undertaking
>> like it seems it would be?
>>
>> -----
>> Bob,  Getting a split gear "loaded" so its springs do not fall out is
>> separate from your RF band switch problem. Do fix the split gear loading
> problem
>> first.
>>
>> -------------
>> Is it normal to have rezero the dial between bands with a newly aligned
>> radio?
>> ----
>> I think Barry explained this one for you. But every band has its own
> crystal
>> in a conversion stage. Unless two crystals happen to have the same error
> then
>> you have to zero adjust for every KC band. Part of normal operation.
>>
>> ----------------
>> And also is it normal to hear sideband artifacts
>> on strong locals as far away as 10 khz on either side of the station with
> a
>> 400' antenna no matter which selectivity position is used or was this
> thing
>> knocked back out of alignment? Thanks,
>>
>> Bob
>> Millbury, Ma
>>
>> -------------------
>> Bob,
>>
>> One hears many thing with an R390 not heard with other receivers. Some of
> it
>> can be alignment. Some can be mechanical filter ring. 400 foot antenna is
> a
>> lot of signal grabber and some broadcast band filtering may be in order
> for you
>> or out right attention.
>>
>> You may want to go to a balanced feed antenna input so you can get the
>> antenna balance and first stage of the RF transformers to tune and thus
> filter some
>> of the strong near frequency signals for you.
>>
>> Good Luck with this.
>> If you have any questions to my cryptic response here, please send some
> more
>> mail back on the R390 reflector and I will do some more details.
>>
>> Roger AI4NI
>>
>>
>>
>>
>> >
>> >
>> >
>>
>>
>>
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