Dick wrote:
What's the best small diameter (<0.25") low loss coax?
How nuts do you want to get? You shouldn't need anything better than a good RG-59 (75 ohms) for a 30' run. For that, I'd probably use Belden 1426A if I were restricted to < 0.25". Good foam RG-6 (also 75 ohms) like Belden 1694A is better, if you can tolerate 7mm diameter (.275"), but at 30' the difference in attenuation will be less than 1 dB.
Note that GPS antenna manufacturers often specify (and supply) 75 ohm RG-59 instead of 50 ohm RG-58, notwithstanding that the antennas and GPS units are 50 ohms. This is because the effects from the relatively small mismatch are more than outweighed by the typically 2 dB/100 ft. loss advantage of RG-59 over RG-58.
At 1 GHz, the losses per 100' of some candidates are: 1/4" Heliax: ~4.5 dB (~5 dB at 1.5 GHz) Belden 1694A: ~6 dB (foam RG-6; 7mm diameter; some brands worse) RG-401: ~7 dB (1/4" semi-rigid coax) Belden 7808A: ~7.5 dB (low loss RG-8X; some others much worse) LMR-240: ~8 dB (low loss RG-8X) Aircell 7: ~8 dB (note: this is 7mm, a bit larger than 1/4") Belden 1426A: ~8.5 (foam RG-59; some types/brands worse) Aircell 5: ~9.4 dB (5mm OD) Best regards, Charles _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
