Simple QRP projects, 10m, 8m, 6m, 4m, FT8, 160m, WSPR, LF/MF, sub-9kHz, nanowaves and other random stuff, some not related to amateur radio.
2 Feb 2015
70cm AM test with low cost modules
This evening I listened for G6ALB on 70cm. Andrew is 3km from me. We both have V2000 vertical co-linear antennas. He was using a very low cost SAW locked TX module, which produced as much FM as AM when modulated with an electret mic. The biggest problem was Andrew's low power and low level of modulation. He needs more mic gain, more TX power (10dB more?) and some pre-emphasis on the audio. TX power today was very low milliwatts. From 433.925MHz up to at least 433.990MHz a lot of squeaks and whistles could be heard, presumably from more local ISM devices. I was receiving G6ALB using an FT817 at about RS41 on FM and weaker on AM. This very initial test produced results that were expected. To use a super-regen module on RX (the intention is a very simple AM voice transceiver) will require G6ALB to be considerably stronger than on these first tests.
Watch George Smart and VK3YE latest Videos:
ReplyDeletehttps://www.youtube.com/watch?v=4leNjynR0DM
https://www.youtube.com/watch?v=TR5WNbspIKI
https://www.youtube.com/watch?v=57HIvGXePD0
I have mine on order 5 for £2.50 delivered inc RX module
73 Steve
Inspired by this post and a mild evening, I did a range test with a UHF module to a 1/4 wave antenna 8 metres high.
ReplyDeleteIt could be heard through suburbia on a handheld 1.5km away. https://www.youtube.com/watch?v=oL1HnjDvT1Q
3km should be possible assuming an 8 metre antenna height both ends.
If a module was fitted onto the top of a small beam that should further the range and eliminate the losses of feeding the RF via a long length of coax.
ReplyDeletePity they are fixed to one frequency. Although as Peter demonstrates this can be varied slightly depending on where the Bias pot is set,
There can be so many different uses for these with a bit of experimenting and thought, APRS beacons comes to mind etc..
73 Steve