Yep good ideas.? I'm also considering the daughter card filtering option.? Unfortunately I tried to buy from QRP labs but it didn't like my credit card for some reason.? Luckily they give instructions on most of it so I bought some of the parts from other places to try to assemble some variation of my own.
Checking with just an RTL-SDR transmitting at 7.15 MHZ I saw a harmonic at about 21 MHZ range that was at the same power as my transmit frequency.? Plus I presume lots of IMD / spurs around 0.75MHZ up and down away from the main transmit frequency at only about -30db.
So definitely need to do something to be able to use it.
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On Sun, Jan 20, 2019 at 05:31 PM, Curt wrote:
Dave
I suggest keeping this surgery within your comfort zone.? Nothing sacred about surface mount parts, but at 45 MHz keep connections short.? I am not yet considering this particular mod - but you could consider using a small daughter board connected with leads to main board.? At the moment with lower bands doing the best - I suggest the LPF filter relay issue is a bigger deal.? Here in our club build we are adding 3 relays on a daughter board.?
I have been trying the approach of using an added xtal filter at C22 - while it corrects spurious we find it inhibits CW transmit power on 40m.?
I suggest insuring your work can be reversed if correction is found not to work well enough - been there, doing that.?
73 Curt
