[R-390] Re: R-390 digest, Vol 1 #919 - 3 msgs

Mon, 8 Dec 2003 09:12:34 -0800 (PST)

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> Today's Topics:
> 
>    1. Re: R-725, the new Holy Grail (Barry Hauser)
>    2. Re: R-725, the new Holy Grail (Scott Seickel)
>    3. The R-725 and the DF story? (John KA1XC)
> 
> --__--__--
> 
> Message: 1
> Date: Sun, 07 Dec 2003 18:54:53 -0500
> From: Barry Hauser <[email protected]>
> Subject: Re: [R-390] R-725, the new Holy Grail
> To: [email protected], [email protected]
> Reply-To: Barry Hauser <[email protected]>
> 
> Hi Todd and gang --
> 
> I'm pretty sure it's been done -- backwards and forwards -- fitting
> an R-390
> IF deck into an R-390A and the other way around.
> 
> Irony Dept.: Just imagine sometime in the not so recent past -- a
> pilgrim
> buys what looks like an R-390A, possibly missing its tag and later
> learns he
> has no mechanical filters and the IF deck looks funny.  There was
> probably a
> time when they were viewed as deficient, second rate, bolyxed,
> whatever.
> Long before the concept of @RARE@ was fully developed in modern
> society.
> 
> One school of though is that, yeah, you can fit a '390 IF deck to a
> '390A,
> or maybe better off just getting an R-390 to keep your "A" company
> and
> switch off when conditions and program content call for it.
> 
> Barry
> 
> 
> 
> ----- Original Message -----
> From: <[email protected]>
> To: <[email protected]>
> Sent: Sunday, December 07, 2003 6:32 PM
> Subject: Re: [R-390] R-725, the new Holy Grail
> 
> 
> > Very interesting to see how desirable the R-725 has become as
> reflected on
> > the end price in the auction. That has spurred my interest in the
> conversion of
> > installing/modifying an R-390 I.F. strip to work in an R-390A.
> Looks like
> with
> > a few hours of time and some re-wiring one could have a working
> clone of
> the
> > R-725. I think the combination would be a good one if someone's
> main
> interest
> > was in Broadcast/Shortwave listening and/or ham-band AM phone
> operation.
> You
> > would have the serviceability and newer design of the R-390A RF
> chassis
> and the
> > somewhat smoother audio of the R-390 I.F. in one package. 73 Todd
> Roberts
> > WD4NGG.
> >
> >
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> 
> 
> 
> --__--__--
> 
> Message: 2
> Reply-To: "Scott Seickel" <[email protected]>
> From: "Scott Seickel" <[email protected]>
> To: <[email protected]>
> Subject: Re: [R-390] R-725, the new Holy Grail
> Date: Sun, 7 Dec 2003 20:12:45 -0500
> 
> 
> 
> > Very interesting to see how desirable the R-725 has become as
> reflected on
> > the end price in the auction.
>  73 Todd Roberts
> > WD4NGG.
> 
> 
> I think the overall condition of it really helped it's value.  It is
> really in sweet condition.  Personally, I can think of a really lot
> of better stuff to buy for $1600 than that radio.  Just my opinion.
> Sure a lot of you agree.
> 
> Scott
> 
> 
> 
> --__--__--
> 
> Message: 3
> From: "John KA1XC" <[email protected]>
> To: "R-390 reflector" <[email protected]>
> Date: Mon, 8 Dec 2003 00:36:18 -0500
> Subject: [R-390] The R-725 and the DF story?
> 
> Since we're on the subject, I'd like to bring up a question that's
> been on
> my mind about the reported purpose of the R-725 and its DF friendly
> IF deck.
> Is DF use really the case, or is this just a story that gets
> repeated?
> 
> While I've often read this explanation, I've never seen any
> documentation referring to what actual DF equipment or systems the
> R-725 was used with. I'm very familiar with the need for carefully
> characterizing the IF phase or group delay characteristics for
> particular
> applications, but I am unfamiliar with any needs for DF. Maybe I
> don't
> understand this requirement but could there be another explanation?
> The
> following is my reasoning.
> 
> DFing to me means determining the location of an emitter
> From what I know about the major HF DF systems used (such as the
> giant
> Wullenwebber arrays that were deployed world-wide) they could be
> simplified
> into three parts:
> 
> i) the antenna array which is used to receive and resolve the emitter
> bearing
> ii) the receiver which allows you to listen in and provides a
> conditioned
> IF output
> iii) the display processing equipment which takes the IF signal and
> extracts
> the amplitude information and puts it in a form which can be used to
> create
> a rotating polar display. This gives you the familiar DF scope with
> the
> propeller shaped display indicating bearing.
> 
> The whole point of this is that it is the emitters amplitude which is
> being
> plotted against bearing, and I just don't see the emitters phase
> components,
> or the IF's, coming into the equation. I've also heard stories told
> by DF
> and intercept operators of such centers being filled with racks and
> racks of
> R-390's, R-390A's, and R-391's, but don't recall R-725's being
> mentioned
> much if at all.
> 
> Perhaps I'm missing something in the above explanation, but I DO have
> some
> applications in mind where linear IF phase would be handy.
> 
> 1) Radio-location, defined as determining where the *receiver* is
> located
> based on known transmitters.
> 
> The transmitted signals contain precisely timed pulse information
> which can
> be translated to distance, so having an IF that preserves the phase
> (and
> therefore the timing) of the pulses is important. But there was lots
> of
> 
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