DuFlon.wbst@Xerox.ARPA (07/15/85)
I am in the market for a >30 MHz scanner/receiver, and have the
following questions and comments:
The Yaesu FRG-9600 seems like a nice unit. It's general coverage
from 60 to 905 MHz, CAT computer and video interface options, and
logical user interface are features I would like to see, especially for
a reasonable price ($459 mail order). Recient messages about ICOM and
Yaesu FRG-8800 battery backed-up RAM containing REQUIRED operating
parameters have me worried. Does anyone have first-hand knowledge if
this is the case with the FRG-9600? Planned obsolescence (or required
maintenance, if the company will be willing to do it into the distant
future) is not a desirable feature in a receiver. BTW, the Kenwood
R-2000 does not have this problem.
Is there any reason that a good quality, 25 element UHF/VHF/FM
television antenna on a rotor wouldn't be as good or better than a
"scanner" antenna? The frequency coverage is about the same, it is
directional, and the antenna feed is low loss 75 ohm coax. I am aware
that impedance matching would be necessary if the scanner input is not
75 ohms.
Finally, thanks to Bob Parnass for his recient review of scanner
features, specifications, and their operation. It was most helpful to
those of us trying to figure out what's out there, and what features are
important.
Ray DuFlon
DuFlon.wbst@Xerox.ARPAparnass@ihu1h.UUCP (Bob Parnass, AJ9S) (07/21/85)
x > ............ Recient messages about ICOM and > Yaesu FRG-8800 battery backed-up RAM containing REQUIRED operating > parameters have me worried. > ............. Planned obsolescence (or required > maintenance, if the company will be willing to do it into the distant > future) is not a desirable feature in a receiver. BTW, the Kenwood > R-2000 does not have this problem. I wouldn't let the RAM/backup design deter one from buying a new ICOM R71A, as I think most people that buy one new will be swapping it for a later model before the lithium battery runs down. The FRG8800 problem, on the other hand, sounds like one that will affect owners of new and used FRG8800 receivers alike. > Is there any reason that a good quality, 25 element UHF/VHF/FM > television antenna on a rotor wouldn't be as good or better than a > "scanner" antenna? The frequency coverage is about the same, it is > directional, and the antenna feed is low loss 75 ohm coax. I am aware > that impedance matching would be necessary if the scanner input is not > 75 ohms. TV Antennas as Scanner Antennas: Textbook Answer 1. Because the lowest TV channel is around 56 MHz, a TV antenna doesn't excel in the 30 - 40 MHz range. 2. Because most stations one would monitor on a scan- ner use vertically polarized antennas, loss due to cross polarization would be experienced if using a horizontal antenna with a scanner. TV Antennas as Scanner Antennas: Experimenter's Answer 1. If you already have a TV antenna installed, try it on the scanner. Although I think you'll do better with a scanner antenna, my philosophy on receiving antennas is: if you can hear what you want to hear, USE it! I use coat hangers soldered into banana plugs on the back of 3 of my scanners. 2. The difference between using a 75 or 50 ohm antenna systems for a scanner receiving antenna is insigni- ficant. The input impedance at the antenna ter- minals of a multi-band scanner is not a constant 50 ohms over the entire frequency range, and 75 ohms is close enough. 3. Remember that there are situations in which one doesn't want a "good" antenna. I monitor a local fire department frequency shared by dozens of towns, but I'm only interested in my own. For this purpose, I use the built-in telescoping antenna, collapsed down a few sections. The majority of scanner purchasers aren't hobbyists, and are content with the telescoping antenna furnished with the radio. Most hobbyists use the "ground plane" type of antenna with a coil in the vertical element for multiband recep- tion. These antennas are made by Antenna Specialists and Radio Shack, among others. The trap is designed to allow reception on 2 or 3 of the conventional bands. Avanti's 801 scanner antenna looks weird, but it too is designed for reception within discrete frequency ranges. A new trend in monitoring is the availability of continu- ous coverage, wide band receivers. Now that reception of the 72-76, 200-400, and 800-1300 MHz bands is practical, one may consider using a set of antennas, each optimized for a particular band, or a single, broad band antenna. Hustler makes a broad band discone antenna for scanner use that sells for about $30. This brings me to another subject. My Hustler discone wouldn't fit on the porch of my apartment, so I'm buying a multi-acre farmette. I won't keep cows in my barn (aka/inlaw suite), nor grow corn, but rather will plant an antenna crop. Netnews submissions and listening activities will, of necessity, be limited during this busy time. -- =============================================================================== Bob Parnass, Bell Telephone Laboratories - ihnp4!ihu1h!parnass - (312)979-5414
mikey@trsvax (07/23/85)
75 to 50 ohm mismatch at the scanner is a 1.5:1 SWR, not much to worry about. And some of the 75 ohm aluminum shiellded cable is VERY LOW loss for the price. As for the TV antenna, it's probably designed to mount horizontally, with a mast up the center. Trying to mount it vertically may be a problem both mechanically and electrically, as a mast in line with the elements will probably affect it a lot. Don't get me wrong, I've used "other" antennas for lots of stuff like scanners and even transmitting. I'm now using an old Radio Shack VHF high band only base monitor antenna for a 2 meter transmitter. Believe it or not, I had to CUT the length down to make it tune. I get EXCELLENT results. (This is the old antenna that was discontinued in 1977 that has a base loaded coil. They sold a base version and a mobile version that were nearly identical. There was a taxi company near me that used the mobile version for their taxis, seems $16.95 was a lot cheaper than the Motorola antenna.) On scanners, almost anything will work. Just get the antenna OUTSIDE and get it as HIGH in the air as you can. mikey at trsvax KA5MJQ