Bill can comment further, but the BPF should be in the signal path in both RX and TX mode.?
In TX mode it cleans up the signal before it goes to the PA. This means that higher-order harmonics of the signal produced by the exciter -- copies of the signal at multiples of the transmit signal -- are filtered out and not amplified by the PA. These would be removed by the LPF anyway before they could hit the antenna, but removing them before the PA helps with signal quality because the PA isn't having to amplify signals at multiple bands simultaneously.
In RX mode the BPF keeps the other bands away from the input to the mixer. If you didn't have the BPF in place you would expect to get a higher noise level in the audio at best, and distortion from strong signals in other bands at worst.
On Wednesday, April 2nd, 2025 at 3:54 PM, epif18 via groups.io <epif18@...> wrote:
Well, I did some more troubleshooting and this is what I found:
I stuck some troubleshooting code at the beginning (first line) of loop().? Draw a line on the display.? Well, looked like setup never exited.? Stuck that code in various places in .ino and eventually found that swrSetup() was hanging up.? I have the SWR_AD7991 installed but not the transformer (shorted RF In to RFOut). I commented #define V12_LPF_SWR_AD7991 out.? Then I commented out swrSetup() and 66.9 ran!
?
Looks like it's not in the latest code on github (KI3P/SDTVer066-9) that was updated 2 weeks ago.
?
I've shut down my radio and brought it back up and all is good.
?
Still a little noisy on 40M but 20M seems to be working great.
?
While I'm at it, when should the BPF_TX and _RX be in or out?? I attached a test cable to the LPF ACC Control connector and those signals are different moving from 66.4 to 66.9.? In 66.4, BPF_RX was out in SSB mode and in when in CW mode.? In 66.9, it appears that BPF_RX is "in" in both modes.?
Thanks
Mark KU3O
?
