AWalker@RUTGERS.ARPA (*Hobbit*) (04/22/85)
How easy would it be to modify the code in a modern PLL HT to enable tuning out-of-band? It would be nice to have some additional receive range without those kludgey band shifter antenna bolt-ons. I would think you can tell the PLL to do whatever you want, you just have to get the software to believe this. _H* -------
parnass@ihu1h.UUCP (Bob Parnass, AJ9S) (05/01/85)
x Out of Band Coverage for 2 Meter Portables > How easy would it be to modify the code in a modern PLL HT to enable tuning > out-of-band? It would be nice to have some additional receive range without > those kludgey band shifter antenna bolt-ons. I would think you can tell the > PLL to do whatever you want, you just have to get the software to believe > this. Changing the firmware in a 2m ht is not for the faint of heart. The older ICOM IC2's range may be extended to 140 - 150 MHz by cutting and soldering, no new components needed. 73 magazine detailed two ways to extend the coverage on the older Kenwood TR2400. One method used the injec- tion signal from the transmit PLL on receive, although the frequency display wouldn't track the true receive frequency. This resembles the old trick of placing the receive crystals into the transmit crystal sockets of older crystal controlled CB radios so they could transmit on 10 meters. Nowadays, 2 meter portables are used for non ham activities, particularly for warfare in the Middle East and Central America. Not wanting to miss a major market segment, Japanese manufacturers have started adding additional frequency coverage capabilities into their 2m rigs. The ICOM IC02AT's coverage can be modified by the addi- tion of a few diodes. The Kenwood TR2600A already cov- ers 140 - 160 MHz on receive right out of the box and can transmit the same wide range by cutting a two com- ponent leads. -- =============================================================================== Bob Parnass, Bell Telephone Laboratories - ihnp4!ihu1h!parnass - (312)979-5414
McAfee.ES@Xerox.ARPA (05/06/85)
I thought that this information from JE1RYH would be of interest to the net. Pete KD6HR ---------------------------------------------------------------- Date: 3 May 85 19:06:14 +0900 (Friday) Subject: Re: Modified PLL rigs To: HamRadio^.ES From: JE1RYH <Ozaki.FX> cc: Ozaki Reply-To: Ozaki.FX Do you think that ICOM, YAESU, KENWOOD and others are making separate CPUs for each band of rigs? No! They use same CPU for series of rigs(e.g. IC-02, IC-03, IC-04s). Nonetheless, they even use the exactly same CPU for JA's, Europes, USAs and other contries( you know, their band plans are bit different from one another). So, you can simply change your rig to cover freq ranges as wide as the CPU has been programed. What makes all the differences are the DIODES and some registors. It's just combination of those diodes and registors to tell CPU which mode(freq range) to operate. For example, my IC-03N (which might be IC-04A in the States) would display 50MHz, 144MHz, 220MHz, 440MHz, and even 1200MHz, too. Of course, it does not receive nor transmits on other bands, because PLL circuit is made for 440MHz band only. Our band plan for 440MHz band is between 430.00MHz thru 439.99MHz, but I could easily enlarge its coverage from 420MHz to 450MHz, by cutting one lead of a diode. If you have thumb wheel type rig, it's much easier to widen its coverage. Try to find the chip named 9122 near the PLL circuitry, that's a programmable devider which control PLL to determine the output frequency. Maybe, you'd have to study a bit about PLL circuits, but once you know the principle of its operation, it would be nothing to change it to whatever the ways you want to. Have fun with your PLLs. 73 & 88s de JE1RYH -- Yuki Ozaki ----------------------------------------------------------------
larry@extel.UUCP (05/16/85)
I have thought many times of attempting to get my IC02AT to cover a larger frequency range primarily to recieve the NOAA weather forcast. I have tried to get a service manual from Icom America without too much luck. Has anyone else gotten one? Ok so I got adventursome and opened up the little monster after it losts its memory in cold weather. Pushing the reset switch fixed that by the way. After finding the diodes used to program the band plan I decided to quit rather than destroying the thing as the diodes were acutally surface mounted transistors. While I am pretty well equiped to work on small circuits I don't have much experience with SMC's. Has anyone been more adventursome than myself and would you like to share? Larry WA9QOO ihnp4!tellab1!extel!larry
ron@brl-tgr.ARPA (Ron Natalie <ron>) (05/20/85)
> > I have thought many times of attempting to get my IC02AT to cover > a larger frequency range primarily to recieve the NOAA weather forcast. I don't know, but 20 MHz is an awfully big shift. You'd better be pretty close to the transmitter, or willing to retune your radio away from the ham bands. Why not go down to radio shock and by a weatherradio. -Ron
larry@extel.UUCP (05/27/85)
Actually receiving NOAA is a moot point as I don't want to mess with the SMC's on the digital board anyway. Larry