Experimenting with the AO-40 satellite

Experimenting with cheap & simple dish feeds:

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Simple can feeds for S band down and L band up:

- quadrifilar backfire helices (18k) for mobile testing (RHCP at the left, LHCP at the right)

- used raw materials (49k) used for the S band dish feed horn :-)

- a closer view of the RHCP/LHCP feed (80k) for S band

- ever ongoing patch feed (17k) projects

- close up view of the S band feed (116k)

- a view of the feed mounted onto a 60 cm dish (111k) with the homebrew P-HEMT LNA and modified Drake D/C

- an overall view of both L and S (115k) band dishes QRV

- the 10 litre L band (58k) can feed at the 3 m dish focus

- the horn was quickly aligned (55k) using wire, string, nails and tape (looks pretty straight...)

- close up view to verify the rust (49k) status :-)

- 300 mW at the feed after cable losses gives easily copiable CW

- 2 W at the feed gives a reasonable SSB signal on the downlink

- RX during these tests: RHCP 60 cm dish, P-HEMT LNA, Drake converter (70 cm IF), ICOM R7000

- TX during these tests: TS700A, LSM-24 transverter, PA2310 5 W amplifier, 3m dish, linear pol.

- an experimental L/S dual band feed (93k) with high L -> S isolation

simultaneous RHCP/LHCP has been implemented via a quarter wave delay plate

- a closeup view of the L band phasing (88k) with a coax 90 degree hybrid

- internal view of the phase shifting hybrid (86k) enclosure

- ellipticity of L and S feeds is excellent separately, matching also

- ellipticity of the S band feed suffers when combined with the L linear probes

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Updated 09.01.2003/Michael Fletcher