I'm surprised there's not more documentation for the Spectrum gear available on the web.
I scanned in the paperwork from some receiver and transmitter strips I bought in 1995 and they seem to circulate around on the web. I've even found and re-downloaded them from various web sites when I was looking for other Spectrum Manuals. If you look at a manual I scanned in as the source... I used to include my business card on the last page (don't do that any more). I also have copies of the SCR-77 Repeater/Base Manual but I think they're the VHF versions. The tx & rx paperwork I scanned in arrived new with some 224 MHz gear I bought and it also quasi covers the other bands. If you don't have it... I can send it to you or you're obviously welcome to download it off the web (from numerous places). I'll look to see if I have anything specific for the 440 band. I do have some working 443 MHz Spectrum Strips... I could measure the crystal fundamental and overtone mode if it's on a plug in set of terminals (not soldered in). Spectrum also configured their products for Oven and ambient air temp operation and of course quite a bit of parts on the board change when they set the operation up for one type or the other. I recently repair a number of modified Spectrum Modules and the savior was a working spare board to use as an example. Spectrum receives a bad rap... for a number of reasons. But I still buy, fix and use them when I can. When they're properly reworked... they can be just as good as many of the other similar products found surplus. cheers, skipp skipp025 at yahoo.com > "w4clj" <mbx-sp...@...> wrote: > > Just received the crystal for a new operating frequency but the formula > Xtal=(f-21.4)/6 shown in the manual is wrong and so is the schematic. > > A second multiplier is in place on the circuit board that is not indicated on > the schematic. Instead of the "divide by 6" factor, the manual should read > Xtal= (f-21.4)/8. This makes a big difference when ordering crystals. The > actual crystals should be in the 50MHz region but when following the manual, > one ends up with crytals in the 70MHz region. > > Does anyone have a copy of the correct schematic? > > Dave > W4CLJ >
