[IRCA] Tuning 1-KHz splits with 2-KC bandwidth (R-390A)
At 07:43 PM 5/6/2007 -0400, you wrote: >Hi Charles, > >Yeah I did, I've been using the 1 KHz filter for that, I'll try your >method and let you know how it works for me, thanks. >I find that most people don't really differentiate between 390's and >390A's especially if they don't own them, that's part of the reason why I >assumed Patrick meant a 390A, also in private correspondance he mentioned an A, > >Bob Bob, The 1-KC bandwidth is too "tight" for AM work, in my opinion, It precludes being able to hear 2 and 3-kHz voice components which are very helpful...maybe essential, for intelligibility. | 2 | | kHz | | |__ --- 151015201530 | | || | 1521 Above is how I think you're tuning BKBSA-1521. The 2-kHz passband centers on 1521. As you can see, 1520 carriers are going to be audible as they are inside the passband. | 2 | | kHz | | |__ --- 151015201530 | | || | 1521 Above, you've "slid" the R-390As frequency up so that it reads something like "1522" on the dial. 1520 carriers are outside the passband. In slowly tuning across 1520 upwards, you should note that the 1521 het appears rather abruptly, As you continue to tune upward, the het should disappear abruptly. That's the sharp-sided shape factor of the R-390A mechanical filters working. The R-390 doesn't have that shape factor. As a matter of fact, the 1-kHz passband is shaped more like a sinewave. Only a crystal lattice filter replicates the shape factor of the mechanical filter. Cheers! Chaz-O Charles A Taylor, WD4INP Greenville, North Carolina ___ IRCA mailing list IRCA@hard-core-dx.com http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: irca@hard-core-dx.com
Re: [IRCA] Tuning 1-Khz splits with 2-KC bandwidth (R-390A)
Tuning splits on 390's is fun. I like to offset tune in 2 or 4 position, as does Charles. Sometimes, reception is clarified by turning on BFO, offsetting by a Kc, and zero beating, with audio set about 2/3 while riding RF gain. Cheap & effective. z ** See what's free at http://www.aol.com. ___ IRCA mailing list IRCA@hard-core-dx.com http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: irca@hard-core-dx.com
[IRCA] Tuning 1-Khz splits with 2-KC bandwidth (R-390A)
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 ___ IRCA mailing list IRCA@hard-core-dx.com http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: irca@hard-core-dx.com
