Woooosh right over your head!
----- Original Message -----
From: Jim Whartenby via R-390 <r-390@mailman.qth.net>
Reply-To: Jim Whartenby <old_ra...@aol.com>
To: 'R-390 Mailing List' <r-390@mailman.qth.net>
Sent: 1/12/2025 3:33:27 PM
Subject: Re: [R-390] R-390 IF Deck
________________________________________________________________________________
Les
No, I meant the R-725/URR, see: https://sv7apq.blogspot.com/2019/03/the-
r725urr-and-tropicon-project.html
The story was that the phase distortion caused by mechanical filters when the R-
390A was used for direction finding caused errors in the DF circuits. Using
the R-390 IF in the R-390A chassis and a few mods to make it work eliminated
these location errors. There are other stories in the above article but one
comment supports the DF story.
Jim
Logic: Method used to arrive at the wrong conclusion, with confidence. Murphy
On Sunday, January 12, 2025 at 03:08:42 PM CST, Les Locklear
<leslockl...@hotmail.com> wrote:
The R-390/URR predates the R-725/URR. you’re thinking about the R-390A/URR…
Sent from my iPadFrom: r-390-boun...@mailman.qth.net <r-390-
boun...@mailman.qth.net> on behalf of Jim Whartenby via R-390 <r-
3...@mailman.qth.net>
Sent: Sunday, January 12, 2025 2:57:26 PM
To: 'R-390 Mailing List' <r-390@mailman.qth.net>
Subject: Re: [R-390] R-390 IF Deck OH, so it is an R-725 wannabe?
Logic: Method used to arrive at the wrong conclusion, with confidence. Murphy
On Sunday, January 12, 2025 at 01:12:01 PM CST, Jacques Fortin
<jacque...@videotron.ca> wrote:
Jim, with all due respect, Byron is asking about the IF deck of a R-390 (a non-
A, if you prefer).
No mechanical filter in there, but a 6 stages IF strip....
73, Jacques, VE2JFE in Montreal
-----Message d'origine-----
De : r-390-boun...@mailman.qth.net <r-390-boun...@mailman.qth.net> De la part
de Jim Whartenby via R-390
Envoyé : 12 janvier 2025 13:56
À : 'R-390 Mailing List' <r-390@mailman.qth.net>
Objet : Re: [R-390] R-390 IF Deck
Where is S504? I see S501, S502 and S503 but no S504 in the schematic or parts
list.
I personally think that the 8kc mechanical filter now has a high insertion loss
due to the internal "rubber" isolator turning into goo or perhaps a weld
connecting a wire to a disk has failed. I have seen both. If one has any
mechanical skill and patients, the filter can be repaired by careful
disassembly and replacing the "rubber" isolator. If it is a broken weld, the
filter is toast. The filter repair info is in the Pearls of Wisdom,
IIRC.Regards,Jim
Logic: Method used to arrive at the wrong conclusion, with confidence. Murphy
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