Flex 1500 works great on 630m

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  • Updated 7 months ago
I am pleased how well my old 1500, once pulled out of retirement, has worked on 575 kHz. However, both RX and TX need external lowpass filters. That a LPF is needed for RX broadcast rejection is no surprise. However, the transverter DDS TX output at f=475 kHz has a glitch at 2f, which causes no end of trouble further down the transmit chain. It is easily cleaned by inserting a pi-section filter with Q=1, namely with a shunt 6.8 nF, a series 17 uh, and a shunt 6.8 nF.
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w8mqw

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Posted 7 months ago

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Andrew Russell

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Well done. I have used my 1500 in a similar way for years.
Andrew VK5CV

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w8mqw

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Thanks Andrew. I got the idea from you.