Re: [IRCA] SP 600 /R390

["Bob Young" <youngbob53@xxxxxxx>]

I think Patrick meant a 390A Charles, and it probably is a peak limiter like 
the others, but mine works one hundred times better in the 390A than any 
other I've got in many different boatanchors, especially in the 388 and 
SP-600's. I just turn it on to the minimum and it doesn't seem to chop the 
peaks very much if at all but the noise is way below the audio level of the 
station, works very well in mine. I've got a couple of 390's but have to 
change the PTO in one of them before I can use it and the other also needs 
some work,

Bob Young
analog, MA
KB1OKL


>From: Charles A Taylor <MWDXer@xxxxxxx>
>Reply-To: Mailing list for the International Radio Club of 
>America<irca@xxxxxxxxxxxxxxxx>
>To: Mailing list for the International Radio Club of 
>America<irca@xxxxxxxxxxxxxxxx>
>Subject: Re: [IRCA] SP 600 /R390
>Date: Sun, 06 May 2007 14:32:24 -0400
>
>At 10:02 AM 5/6/2007 -0700, you wrote:
> >Bob,
> >
> >I never knew that. Then the R-390 does have an honest Noise Blanker and
> >not a Noise Limiter as the SP 600 had. Now that is interesting. I wonder
> >what kind of circuit the R 390 uses? Anyone know? That diode set up in
> >the SP-600 never did anything much except distort the audio as you
> >mentioned. That was the only reason I sold the SP 600. It was one great
> >receiver and netted me a lot of great DX through the years. One thing I
> >really miss is the crystal phasing. I wish the crystal filters in the
> >SPR4 had phasing.
> >73,
> >Patrick
> >Patrick Martin
>
>Patrick,
>
>AFAIK, the R-390's NOISE LIMITER is essentially the same as the R-390A's
>NOISE LIMITER. Neither are noise blankers in the proper sense of the
>term. All they do is chop off the audio at a predetermined level as set
>by the operator by adjusting the LIMITER pot. Like the SP-600, they tend
>to distort the audio.
>
>The R-390A is the result of a cost-reduction contract written by the US
>Army Signal Corps with Collins Radio Corp. The R-390A was a great deal
>cheaper per unit than the R-390. But the R-390A has the mechanical
>filters, and THAT, sir, is the important difference! Every receiver, w/
>the exception of the R8B, that I have owned I've had to supply either
>a crystal lattice filter or a mechanical filter to supplement the
>selectivity characteristics.
>
>The lack of a good product detector and a good noise blanker are the
>prime drawbacks of the R-390 family.
>
>And the noise blanker of the R8B is "finicky" in that, if the incoming
>signal is above a certain level, the NB ceases to operate. I think
>that's because the R8B's NB has an AGC input to the NB.
>
>Now go climb a tree!
>
>Kindest regards,
>
>Charles
>
>
>Charles A Taylor, WD4INP
>Greenville, North Carolina
>
>
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