[R-390] Poor man's R389

[Cecil Acuff]

It has been suggested that for beacon hunting on LF the AGC should be 
disabled on receivers that have AGC, mainly because of the atmospheric noise 
in that part of the spectrum.  Static crashes would keep the radio 
desensitized due to constant AGC action.  That being said frequency 
selective voltmeters are a great choice.  I think with the proper mods they 
make excellent  LF/VLF receivers.

I'm currently massaging a very nice W&G SPM-15.  It has a built in 
selectable low pass filter that begins to roll off at 620 Khz. It has three 
crystal filters...3.1 Khz, 1.9 Khz and 25 Hz.  The 25 Hz is great for beacon 
hunting.  It has flywheel tuning in selectable steps down to 1 Hz and 
digital step tuning with selectable step sizes.  Has a 600 ohm output for 
connection to an external amplifier or headphones.

I would imagine it cost more new than the 389 did in it's day....but it was 
designed as a piece of test equipment.

It's built like a tank and I would expect it to be shielded internally to 
the hilt. (it's portable and can be battery powered)

But that's just my 2 cents worth....

May not be for everyone....

Cecil....


----- Original Message ----- 
From: "Bob" <enigma_y_2000 at yahoo.com>
To: <r-390 at mailman.qth.net>
Sent: Monday, March 13, 2006 1:40 PM
Subject: [R-390] Poor man's R389


> Hi,
>
> Regarding using various selective voltmeters as
> receivers, all of the ones I've used have no AGC.
>
> Bob
>
> --- r-390-request at mailman.qth.net wrote:
>
>> Send R-390 mailing list submissions to
>> r-390 at mailman.qth.net
>>
>> To subscribe or unsubscribe via the World Wide Web,
>> visit
>> http://mailman.qth.net/mailman/listinfo/r-390
>> or, via email, send a message with subject or body
>> 'help' to
>> r-390-request at mailman.qth.net
>>
>> You can reach the person managing the list at
>> r-390-owner at mailman.qth.net
>>
>> When replying, please edit your Subject line so it
>> is more specific
>> than "Re: Contents of R-390 digest..."
>>
>>
>> Today's Topics:
>>
>>    1. Re: VFO squirreliness solved FOR GOOD (Tim
>> Shoppa)
>>    2. Wanted: junker Cosmos PTO's (Tim Shoppa)
>>    3. R220-URR (mike Kana)
>>    4. Re: VFO squirreliness solved FOR GOOD
>> (DJED1 at aol.com)
>>    5. Matching info wanted (Barry)
>>    6. PTO success (DJED1 at aol.com)
>>    7. Poor mans R 389 receiver (Perry Sandeen)
>>    8. Re: PTO success (Joe Foley)
>>    9. Re: R220-URR (roy.morgan at nist.gov)
>>
>>
>>
> ----------------------------------------------------------------------
>>
>> Message: 1
>> Date: Sun, 12 Mar 2006 13:12:57 -0500
>> From: shoppa_r390a at trailing-edge.com (Tim Shoppa)
>> Subject: Re: [R-390] VFO squirreliness solved FOR
>> GOOD
>> To: shoppa_r390a at trailing-edge.com,
>> R-390 at mailman.qth.net,
>> DJED1 at aol.com
>> Message-ID:
>>
> <20060312181257.3EA9C104000A at mini-me.trailing-edge.com>
>> Content-Type: text/plain; charset=us-ascii
>>
>> DJED1 at aol.com wrote:
>> > entire threaded shaft.  I also resoldered the
>> small  caps as Les had
>> > suggested.  I put it in the radio tonight, and it
>> tunes  great- no warbles.  The only
>> > problem I have is that it's off about 2 Kc
>> end-to-end, and the variation is
>> > not linear.  I'll tweak the end point and  see how
>> close I can come- it will
>> > probably meet the original specs when  completed,
>> but won't be as good as a
>> > tweaked Cosmos.
>> > Speaking of which, I also tweaked the end point on
>> the Cosmos because it  was
>> > out by 1 Kc.  Fixed that right up, but now
>> intermediate points are out  by as
>> > much as 1.8 Kc, where they were within 0.4 before
>> I touched it.  And  the
>> > strange thing is that all the 25Kc points are off
>> the same amount- 1.8  Kc.  All
>> > the 100 Kc points are right on, and the 75 Kc
>> points are out about  0.8 Kc,
>> > and also all the same.  Very strange.  I'll look
>> at the data  tomorrow and
>> > decide if I want to tweak all those little screws,
>> or just put the  end point
>> > adjustment back to where it was.
>>
>> The endpoint adjustment does interact at least a
>> little with the calibration.
>>
>> A couple kc is the limit of adjustment possible with
>> the little
>> linearity screws.
>>
>> I think that in some cases it may be wiser to add
>> some small amount
>> of capacitance rather than tweak the endpoint. Maybe
>> I'll experiment
>> with that tomorrow, AFTER replacing the toilet AND
>> seeding the lawn AND
>> installing the ceiling fan... (meaning it probably
>> won't happen!)
>>
>> > While I was in the radio, I found I had a bunch of
>> BBODs in the IF.  I
>> > thought I had all Vitamin Q metal caps, but I was
>> mistaken.  I don't have a  full
>> > set of replacements, but I did replace C553 with
>> an Orange Drop, so at  least
>> > that is taken care of.
>>
>> Was C553 a BBOD? The IF decks I've owned had BBOD's
>> in a lot of not-so-
>> critical-for-leakage places (e.g. screen and
>> filament bypasses) but better
>> quality metal cans - Vitamin Q's or Westcaps - at
>> the filters.
>>
>> Tim.
>>
>>
>> ------------------------------
>>
>> Message: 2
>> Date: Sun, 12 Mar 2006 13:23:45 -0500
>> From: shoppa_r390a at trailing-edge.com (Tim Shoppa)
>> Subject: [R-390] Wanted: junker Cosmos PTO's
>> To: r-390 at mailman.qth.net
>> Message-ID:
>>
> <20060312182345.DA29C8C00AA at mini-me.trailing-edge.com>
>> Content-Type: text/plain; charset=us-ascii
>>
>> You guys may recall my voyage into the heart of my
>> VFO (pretty much
>> tearing down every single component in the can) a
>> few weeks ago.
>>
>> In an effort to learn more, I would like to find a
>> few truly junker
>> quality PTO's for me to tear apart and measure and
>> reassemble in
>> probably unrecognizable form. Probably prefer Cosmos
>> mechanisms but
>> I am willing to learn about others. And I am truly
>> truly looking for
>> basket cases here, whatever I do to these will make
>> Frankenstein
>> look like a wax job. I am mostly interested in the
>> stuff inside
>> the can so if parts are missing/lost/hopelessly
>> damaged on the outside
>> that is fine by me.
>>
>> Also interested in junker BFO reactors for similar
>> experimentation.
>>
>> Will trade NOS tubes (usually JAN or British
>> mil-spec) and/or
>> 390A RF deck miscellany (springs, clamps, gears,
>> etc.) for them.
>> I also have some original 390A AC filters. Will also
>> part with small
>> quantities of cash and a good but used ballast tubes
>> if sufficiently
>> motivated.
>>
>> Tim KA0BTD
>>
>>
>> ------------------------------
>>
>> Message: 3
>> Date: Sun, 12 Mar 2006 10:25:30 -0800 (PST)
>> From: mike Kana <aa9il at sbcglobal.net>
>> Subject: [R-390] R220-URR
>> To: r-390 at mailman.qth.net
>> Message-ID:
>>
> <20060312182530.63151.qmail at web82204.mail.mud.yahoo.com>
>> Content-Type: text/plain; charset=iso-8859-1
>>
>> Hi All
>>
>> I recently picked up a Motorola R220/URR receiver.
>> Did some web searches but didnt find too much
>> information on this set.  Just out of curiosity,
>> what
>> were they used for?  Any information would be
>> appreciated.
>>
>> Thanks
>> Mike
>> AA9IL
>>
>>
>>
>> ------------------------------
>>
>> Message: 4
>> Date: Sun, 12 Mar 2006 15:19:15 EST
>> From: DJED1 at aol.com
>> Subject: Re: [R-390] VFO squirreliness solved FOR
>> GOOD
>> To: shoppa_r390a at trailing-edge.com,
>> R-390 at mailman.qth.net
>> Message-ID: <2b2.632f4fa.3145dc43 at aol.com>
>> Content-Type: text/plain; charset="US-ASCII"
>>
>> Re: was C553 a BBOD?
>> No, it was a glass and metal capacitor.  I checked
>> it after pulling it  out
>> by putting 500V thru a microammeter into the cap.
>> Not even one  microamp of
>> leakage.  I checked a couple of BBOD I had laying
>> around
> === message truncated ===
>
>
> __________________________________________________
> Do You Yahoo!?
> Tired of spam?  Yahoo! Mail has the best spam protection around
> http://mail.yahoo.com
> _____________________________________________________________
> R-390 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/r-390
> Help: http://mailman.qth.net/faq.htm
> Post: mailto:R-390 at mailman.qth.net
> Unsubscribe: http://mailman.qth.net/mailman/options/r-390
>