[IRCA] Tuning 1-Khz splits with 2-KC bandwidth (R-390A)

[Charles A Taylor <MWDXer@xxxxxxx>]

At 03:23 PM 5/6/2007 -0400, you wrote:
>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
>

OK, Bob.

Did you read after my observations about R-390()/URR's noise limiter,
the right way to tune in 2-KC bandwidth for 1-kHz splits?

Instead of "straddling" your desired station in the center of the 2-KC
bandwidth (which puts the "even" channel at the edge of, and inside
the passband), tune the R-390A AWAY from the "even" channel so that
your "split" is at the high or low edge of the passband. Then the
excellent shape factor of a good mechanical filter really shines.

2 kHz is about optimal if that's all you have. But the R-390A's 4-
KC bandwidth is better for intelligibility, in many instances.

Back in my last year of the Navy (1972, in Coronado, CA), I bought a
nice GR-78 communications receiver kit from Heath Co. I added an I-F
jack (455 kHz) to the back apron, and bought a Collins 2.1-kHz
mechanical filter. Built a "Q-5er" receiver tail end around that
mechanical filter. Took them to the Philippines 1972-1973.

For DXing, I used the "Q-5er." The audio was somewhat muffled, but
Collins mechanical filters were (and still are) expensive, and I
didn't want to buy a 4-kHz mechanical filter. For general listening,
I listened through the GR-78's I-F and audio strip.

So you see, you don't need a phasing control on an R-390A.

Know what I mean, Vern?

Trees at yah!

Charles A Taylor, WD4INP
Greenville, North Carolina 


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