Jim - W5ZIT wrote:
>I am trying to move a Q 202 G from the 170 mHz range down to the 147 mHz
>range and have run into a problem on the notch tuning. The high pass
>tuning works like a charm and has a good pass and notch characteristic.
>The low pass side is another story. The pass tuning works fine, but I
>can't get a notch. With the tuning rods all the way in, it is starting
>to notch, but only about 20 db.
>
>
>
Eric - WB5FLY wrote:
>Jim,
>
>Sinclair makes two harness assemblies for that duplexer. The jumpers are
>about two inches longer in the low-range harness, and that makes a world of
>difference. You can order the low-split harness directly from Sinclair. Go
>to:
>www.sinctech.com
>Make it very clear that you want the "low range" harness, as some of the
>Sinclair sales folk seemed to be unaware of its availability, the last time
>I called them. A year or so ago, that harness cost about $145. It's all in
>one piece, with crimped connections. As I recall, the low range was for
>136-150 MHz, and the high range was for 150-174 MHz.
>
>Most Bp/Br cavities will have one notch above and one notch below the pass
>frequency. I have tuned several Sinclair duplexers of this design, and they
>all tuned up perfectly once the correct harness was installed.
>
>73, Eric Lemmon WB6FLY
>
Eric - I took your advice and built up a couple of jumpers to go from
the cans back to the tee in the harness on the low pass side and made
them 2 inches longer than the old ones as you suggested and presto -
nice deep null with the tuning rods.
Thanks to all for the feedback, and thanks to the list for helping to
solve this problem.
73 - Jim W5ZIT
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