RF Switch - Initial Testing

Discussion about this major DATV Project. See https://wiki.batc.org.uk/The_Portsdown_Transmitter
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M1ASR
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Joined: Mon Dec 11, 2017 8:24 pm

RF Switch - Initial Testing

Post by M1ASR » Fri Mar 02, 2018 2:51 am

Hi, I am building the transmitter in stages and have come to testing the RF Switch. I don’t have a Spectrum Analyser, so just using a signal generator and scope for testing prior to connecting the FM. The unit switches bands as designed. However, I noticed that the sine wave amplitude drops by about 1.5db across the switch. Wondered if this was normal? The voltage to the ADG904 is ok at 2.75v.

The DC voltage at pin 10 is 0.5v (RFC) which looks correct given the values of R1&R2. However, this 0.5v is present at all the 904 output pins even when ports switched off, wondered if this was correct?

Logic side working fine and switching 904 correctly.

Wanted to check before I connect FM to RF Switch.

Thank you in advance.

Graham M1ASR
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