Receive chain details

The 21 element X-pol yagis from YU1CF of Antenna Amplifiers offer 24.1dBi gain for the stack of 4 yagi.

The receive chain consists of a cavity Low Noise Amplifier (LNA) followed by a 2nd stage LNA to provide the gain necessary for a high performance SDR. This setup provide optimum P1dB and bandwidth.

The choice for the 1st stage of the RX chain is high performance cavity LNA with gain of 20.5dB and NF 0.26dB. Its has its 2nd amplifier stage on the  PCB  replaced with Bandpass and Elliptic filters.  The LNA is from Radio Astronomy Supplies and was made by Tommy WD5AGO and has P1dB +12dBm and was chosen due to my high noise city location.

The 2nd stage LNA is Kuhne LNA. Its gain is 20.4dB and NF 0.31dB. Its got good IP3 specifications (typ =27dBm) and Helical filters for good selectivity.

The four LNA's and three relays up the tower fed from X-pol yagi's drive two separate receive systems.

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This diagram shows how all the software packages work together to keep track of the moon, correct for doppler, log contacts and decode Q65 or JT65.

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The two separate H and V pol receive systems drive a LinkRF IQ+ SDR receiver. This allows for 4 separate WSJT-X instances to operate on H, 45, V and 135 degrees polarisation. Amazing to watch as signals come inat different polarisations due to faraday rotation.

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I run two Kuhne transverters (H-pol & V-pol) that feed the two receivers in the K4D. This system runs in parallel with the IQ+ SDR and provides 0 and 90 degrees (H&V) inputs to two WSJT-X instances

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The IQ+ feeds IQ stream to Linrad SDR which is an application on the PC. Linrad provides drives MAP65 which is used for a band scope as well as 4 instances of WSJT-X.

While this is happening two Kuhne transverters are used to feed the two receivers in the Elecraft K4D

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