GRAPES 56KB Modem FAQ

What comes in a Full Kit?

The Full Kits include 3 printed circuit boards, the parts for the PCB's, a State Eprom, 37 pages of documentation (including 11x17 schematics) and a support diskette.

What other parts will I need? To complete the construction of your 56K modem, you will need to supply a case, interconnecting cables and connectors, a power supply and frequency determining crystals. The power requirements are 0.5A @ +5 volts and 0.1A @ -5 volts.

How do I drive the modem? The documentation provides instructions to modify your tnc-2 for operation as a "kiss56 tnc". However, the tnc-2 serial port is limited to 38.4kbps, so you may want to use the Ottawa PI2 Card to fully utilize the modem. The PI cards are easily capable of sustained 56kbps thruput (they've been tested to over 460kbps!). The cards are available from the Ottawa Amateur Radio Club for about $135 US.

What software will I need? Most users typically run some version of KA9Q NOS on their computer to drive either the kiss56 tnc or the PI cards. We run the latest version of JNOS110 on the GRAPES 56k Wide Area Net. If you plan use JNOS with the PI cards, make sure that the PI driver has been compiled in.

What about transverters and amplifiers?

The 56K modems output 1 milliwatt on 29 MHz, so you will need to purchase a transverter to convert the 29 MHz to your desired band. The transverter chosen should switch as quickly as possible in the 5-15 msec range to be effective. Usually any linear transverter used for SSB will work, provided it switches fast enough.

We use the Microwave Modules MMT 432-28S and MMT 220-28S units. Both output about 10 watts. They are available for about $250US thru Advanced Radio Technology Limited, Bramley U.K. Telephone 0113-236-1973, fax 0113-2361-1988. They also stock the full line of MMT linear amps with outputs up to 100 watts.

Maple Leaf Communications (Bob Morton, VE3BFM) ships the SincLabs 220 transverters for about $280 US. We have two of these 10 watt units and they seem to work fine. We believe he's working on a new 35 watt transverter. For more info, contact Bob at 705-435-0689 or RR #1, Everett, ONTARIO,Canada, L0M 1J0.

If I just order a documentation set now, will you later allow credit for it? Yes, documentation sets are creditable towards the full parts kits or board sets and the board sets are also creditable towards the full parts kits.