It seemed to me there are a lot of wireless devices available now that can be incorporated in our modes of communication, particularly if those devices are no longer marketable, out-of-date, and subject to “close-out” sales. The 900 MHz cordless phone falls into this category. In some venues, they're advertised for as low as $9.99. I've read some web articles about folks using cellphones and converting them for 33 cm, but nothing about using the cheaper “cordless” phones. So, I decided to try my hand at using a 900 MHz cordless phone unit on the amateur 33 cm band. Here are my first results.
Hardware: 900 MHz analog cordless phone set, PC, dual-band FM rig.
Software: SSTV software capable of transmitting and receiving.
I purchased a VTech T2101 900 MHz cordless for $14.95. Most 900 MHz cordless phones are analog and use wideband FM modulation. Perfect! I downloaded and used Chroma Pix SSTV software (I do plan on registering my copy, it's so useful). It's available from…
Most dual-band rigs have receivable cellphone frequencies blocked above 913 MHz. So, it's necessary to have either the base unit or handset unit of the cordless phone transmit in the 902-913 MHz range. Having the base unit transmit in this range is a bonus as the base unit now becomes a full-duplex repeater and extends the useable range of the device.
The first JPG is a compressed version of my QSL card as it was transmitted from a laptop. The 900 MHz cordless phone handset was careful modified with an audio cable and 3.5 mm plug to interface with the laptop's soundcard. The handset transmitted the SSTV image on 924 MHz to the cordless phone base unit.
The second JPG is the received QSL card that was re-transmitted from the cordless phone base on 903.0 MHz to a FT-7800R dual-band FM rig. The external speaker output of the FT-7800R was connected to the soundcard of another PC.
The original NiMH battery pack has been replaced with an AC adapter for continuous service. After purchasing a 10W power amplifier and a 5dBi commercial antenna, the cordless phone is now co-ordinated as a SSTV beacon operating on 903.3 MHz in Kennewick, WA. The output is a webcam/weathercam with CW ID.