TH28 Date: 10 Oct 92 00:10:26 EDT (Sat) From: wa2ise@kb7uv.#nli.ny.usa (BOB) Subject: TH28 mod files The below info is a merge of multiple sources, which almost agree. I have NOT tried or verified this info, proceed at your own risk! I bought a couple of TH28A's recently in the States and the guy in the shop did the mods for me on the spot. The features I have on the radios Rx AM 118.000 - 135.995 Tx/Rx FM 136.000 - 173.995 Rx FM 340.000 - 399.995 Rx FM 400.000 - 519.995 Note: The poor thing does not like being tuned much over 500 MHz, it beeps at you in complaint. Here are the diode settings that are in my radios: ! o o o o ! ! ! ! ! ! I.C. o o o o ! !_______________ ^ ^ D15 D12 o o o o ! o o o o ^ ^ D11 D8 I can therefore confirm that the above freq. ranges and the above diode settings definitely work !! Cheers, Iain Campbell iain@vision.rs.ch ___________________________________________________________________________ additional info (source:jonathan@nova.decio.nd.edu (Jonathan Bradshaw) who got it from:LAIRDPG@lub001.lamar.edu) NOTE: Diodes D15 & D14 are NOT present in the American version. 4) Remove diodes D8 and D10. 5) Install one of these diodes in D14. (AM and FM are switched automatically according to the frequency range.) To switch between the modes, press the [F] key for one second, then press the [LOW] key. This will switch between: a) Amateur VHF band (136 Mhz to 174 Mhz). b) 340 Mhz band (340 Mhz to 400 Mhz). c) Aircraft band (118 Mhz to 136 Mhz). To get the extended amateur UHF receive, press the [BAND] key while in the 136 Mhz to 174 Mhz mode. -------------------------------------------------------------------------- From: unbham@jupiter.sun.csd.unb.ca (UNB Amateur Radio) 4) Receive from 118 Mhz to 136 Mhz. (AM) This mod comes from simply holding down F and hitting LOW. If this is all you want, don't cut anything. By just cutting diode 9, you enable the wide band receive on UHF (from 400-520) and from 360-400 by hitting F and LOW. I would be careful when cutting diode D10 out though, I did it (I've done surface mount mods before) and my row 3 keys stopped working (MEM, 3, etc) I am positive I didn't clip the wrong diode because I clipped the connection leading out from the diode (you'll see what I mean...) Derek NOTE: I haven't tried or verified this, proceed at your own risk! And do not transmit outside of legal bands. WA2ISE