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IF tap point for panadapter?  

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summitradio
(@summitradio)
Active Member

Is there a way to get a real 8 mhz IF tap point for the 930 or 940 to use the sm 220.  The IF out of the back is at audio (useless) The plan is to find a good tap and rewire the IF jack on the back to use it.  

 

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Posted : 14/12/2018 3:30 pm
ak6ok
(@ak6ok)
Member Admin

I am not an expert on that subject but I do know a guy that is. I'll try and get him over here to answer this one! Thanks for posting!

Jeff AK6OK

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Posted : 17/12/2018 2:51 pm
dave
 dave
(@dave)
New Member

I have not actually tried tapping the IF chain in the TS-930, but it seems to be relatively easy. 

The TS-930 has rear panel connector for an IF output, designed for use with the SM-220 Station Monitor.  Unfortunately,  that is from the 4th IF stage, 100 kHz, and is designed solely to allow visual examination of the transmit signal waveform, and is extremely narrow banded. 

For a Panadapter, the best tap would be from the 1st IF, which is 44.93 Mhz.  This signal is the output of the RF unit after the first mixer, and its bandwidth is only limited by the input Band Pass Filter for the selected band.  This signal can be tapped at the "RIF" input to the signal unit.

The 2nd IF, 8.83 Mhz, the center frequency for SSB and CW filters, is often discussed as useful for an IF tap to a Panadapter, but the input from the 1st IF Amp/Mixer stage to the 2nd mixer is filtered through a crystal filter which limits the bandwidth to 10 kHz. 

The next time I have my TS-930 on the bench, I will connect the 1st IF to my SDR to see if it can be useful.

Cheers

Dave

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Posted : 18/12/2018 4:38 pm
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