Anyone know how to mod the Icom F-420 to TX/RX the entire 430-470 or 400-470? It is at it's stock range of 450-470.

Would love to add the ham bands to it, instead of taking my HT for lomg travels.

73!

Here's what I dug up:

This radio is a 440 MHz workhorse supplied in the 400-430 MHz Range. The radio is capable up operating at higher frequencies for a maximum bandwidth of 30 MHz. There is a hardware change and a software change. First the hardware change:

Open the bottom of the radio and place the front of the radio towards you. Locate the Tx and Rx VCOs, they are on the left side of a rectangular metal piece. The Rx Vco is at the top away from you and the Tx Vco is below that. Then locate a point marked "cp1" just to the left of that can. Adust to the highest frequency that you wish to tune and set it to just less than 7.75 volts with a high impedence voltmeter. Increasing the slug brings the lock voltage down. Then transmit at the highest frquency and adjust the tx vco for no more than 7.75 volts. You may have to make a few tranmissions adjusting slowly until you get the vco to lock. This now sets your bandwidth. Just to make sure, change to your lowest operating frequency and make sure your radio still oscillates. If not, the display will flash.

To adjust the radio in software you will need the following cable: OPC478+OPC592 The OPC592 is a special jumper cable that goes on the end of the OPC478 and connects to the mic jack of the F420. You will also need a copy of ICOM Software CSF300 that you can use to program the frequencies and adjust the radio receiver. I DO NOT PROVIDE THIS SOFTWARE! It is available on the 'Net'. This program runs on MSDOS. Using the program csf300.exe program your frequencies .5 MHz from 400 to 500 MHz. Use this program to determine the range you want to use with this radio. Please note, the low-split (400-430 MHz) version only goes up to approximately 455 MHz. This tuning procedure is generic. Now program in the frequencies you want to use. Once you have programmed your radio you now have to tune it. This is done electronically. You will now have to run a program called "adjust.exe". Run it in a DOS window directly. You will be given 4 switches to select the program. Usually "adjust /A /1" (do not tpe the ") works fine.

Set the curser at "D/A BP T1" and press "F9". This will tune the receiver front end for the best value for the frequencies chosen. Exit from the program and your radio is now tuned. Do not forget to set the squelch control in the settings screen of csf300.exe

Thanks... I'll see what I can do on this end. I got both the cable and software already...

73!

Same topic, different question...

Anyone know what the mods are to have the F420 units act like a repeater (seperate TX and RX units). I know you need the OPC-617 cable to interface the two, but I also heard that you need to make an internal jumper to the radios in order to receive certain data from each other...

Any takes on this one...?


_{(Note: I'm too lazy to wait for the lit I ordered to arrive in the mail -- the repeater was supposed to be operational two weeks ago!!)}

Hmmm...I have not heard of that; I'll have to check with my Icom source.

I would personally be careful about using a mobile radio as a repeater transmitter. If you do, make sure you invest in a good heat sink and/or a cooling fan, else your PA isn't going to be very happy with you. Also when operating in extended transmit, any SWR mis-match is going to be signifigantly multiplied.

Oh yeah. I'm well aware of that. I've installed a heavy-duty fan that sends air straight across the fins of the TX radio. This is my second successful system that I've built. The first was out of an old GE Exec II base. Converted it to repeater with a few jumpers. Knocked out a few 2m repeaters and a 467 system 60 miles away after I installed it on a mountain site. Oops!

It's down at my shop til I find a new site. The site owner said $50/month, then hiked it up to $200/month. I only paid him $100 and left the site after he told me this and when I found out that he disconnected my system and powered it off because he didn't want to listen to the subtle audio leaking out of my aux speaker.

Eh, oh well. His loss, and my gain. The site wasn't even worth the $50 to begin with... Looking at another, twice the height and a commercial site at that for around $100. Better deal me thinks.

... (blah blah blah...)

-R