Mon Jun 27, 2016 7:45 am
OK. If you are really serious about working on this unit, the first thing you should do is pull down the PDF of the Siratrol manual and read it over so you can get a sense of what the equipment can do as you have it. According to the book (found it in about 2 mins with a Google search), the receiver board you have will actually do 30-54 MHZ, so you cover the 6 meter ham band with it and I'd bet you could sufficiently drop it to get into 10 meters if you really wanted to - if you have a ham license of course. However, with a low band board you don't really have many practical options unless you hold a commercial license for a business channel.
It's not enough to just purchase a crystal and solder it in place of another one, you have to align the receiver and make sure it's on frequency to whatever channel you select. And, no you can't make a low band receiver do VHF or UHF. If by some unlikely chance you did find an frequency for low power operation and you ordered & changed the crystal, you had better have a DC voltmeter, an RF signal generator that can also generate 1000hz for alignment, and a frequency standard for discriminator adjustment handy to realign the receiver. A radio shop can do it for you, but you're looking at bench charges, probably .5/hr labor minimum. Shops now typically charge $80/hr and up for labor. You specifically asked about equipment - so that's the minimum you need to bench the unit for a channel change. Oh, and all the necessary probes, clips etc... to attach to the test points and do RF signal injection, not to mention a soldering iron, a desolder station (or solder wick) to work on the board, and a new crystal itself for the crystal swap.
If you want to do either VHF high band or UHF, you're going to need to find a used receiver board somewhere and swap it out. You now have an additional problem on VHF and UHF in that the Siratrol RF boards are older technology and will probably have adjacent channel receive issues with the new narrow-band standards now in effect if you have an adjacent channel user (ducting, CCI, etc etc...).
The 30-second version of all this is that the low band receive board is a paperweight. Dump it & get another board if you want to do anything serious with the unit. And brace your wallet because you're fixing to spend probably three figures to get it running on a VHF or UHF channel. Before you play with the tone decoding.
Brevard County EM - retired (31 years govt. service), it's mid-point career change time! Also system operator of
http://www.newcaprice.com, the support site for privately owned Caprice PPV's.