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<blockquote data-quote="s-band" data-source="post: 972954" data-attributes="member: 407744">I was clearing out some junk and found a duff thermocouple from the gas boiler. What would any normal person do with it? Make a helical antenna. I wound it on an old SMW Ku LNB and attached it to the L-Band plate. It was a bit low in frequency so I tightened it (SMW X-Line aren’t good for L band). EbNo with different amps on 25E 600bps using the Airspy with antenna on window sill:No pre-amp and 3dB cable loss: 6dBMGA 30889 (2dB NF 15dB gain) at antenna: 15dB2 ATF 10136 GaAs (&lt;.4dB NF 25dB gain) at antenna: 25dB25E &amp; 15W 10500 with GaAs LNA give about 5-7dB EbNo and not many “bad CRC”. That’s about the same as I got with the 2 turn feed &amp; a GaAs LNA on an old 35cm BSB dish probably indicating that I was not illuminating the dish very well (it should have about 13dB gain at 1.5G).25E signals are still visible when pointing at 15W and vice versa and it’s much more susceptible to interference. This pic 15W_helical_10500_gaas_lna, shows 25E sigs to the left of the 15W ones.Calculated gain, for a 4.5t helical, is around 11.5dBi. My messy one? 9-10dB? A 20 turn should give ~6dB more i.e. a decent margin. The front to back ratio might be better on a dish though.[ATTACH]93650[/ATTACH] [ATTACH]93651[/ATTACH][ATTACH]93655[/ATTACH][ATTACH]93652[/ATTACH] [ATTACH]93653[/ATTACH] [ATTACH]93654[/ATTACH]</blockquote>

[QUOTE="s-band, post: 972954, member: 407744"] I was clearing out some junk and found a duff thermocouple from the gas boiler. What would any normal person do with it? Make a helical antenna. I wound it on an old SMW Ku LNB and attached it to the L-Band plate. It was a bit low in frequency so I tightened it (SMW X-Line aren’t good for L band). EbNo with different amps on 25E 600bps using the Airspy with antenna on window sill: No pre-amp and 3dB cable loss: 6dB MGA 30889 (2dB NF 15dB gain) at antenna: 15dB 2 ATF 10136 GaAs (<.4dB NF 25dB gain) at antenna: 25dB 25E & 15W 10500 with GaAs LNA give about 5-7dB EbNo and not many “bad CRC”. That’s about the same as I got with the 2 turn feed & a GaAs LNA on an old 35cm BSB dish probably indicating that I was not illuminating the dish very well (it should have about 13dB gain at 1.5G). 25E signals are still visible when pointing at 15W and vice versa and it’s much more susceptible to interference. This pic 15W_helical_10500_gaas_lna, shows 25E sigs to the left of the 15W ones. Calculated gain, for a 4.5t helical, is around 11.5dBi. My messy one? 9-10dB? A 20 turn should give ~6dB more i.e. a decent margin. The front to back ratio might be better on a dish though. [ATTACH]93650[/ATTACH] [ATTACH]93651[/ATTACH][ATTACH]93655[/ATTACH][ATTACH]93652[/ATTACH] [ATTACH]93653[/ATTACH] [ATTACH]93654[/ATTACH] [/QUOTE]

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