Jim,
The problem is caused by overload of the RX preamp, and possibly front end of the 70 cm rig. You will still have the (same) preamp, and the converter has its own front end. So no, that will not likely do any good. Getting as much separation between the antennas, a good preamp, using the mode-J filter which Drew mentioned, and running minimum power are your best bets. With a good mode-J filter, SSB preamp, and 10' between the uplink and down link antennas, I can run 50 watts TX and barely hear any hiss. If you are using linear antennas, using different orientation between TX and RX will give you a few more dB of isolation.
People do use your suggested arrangement with a TS-2000 to avoid the downlink birdie on SO-50.
73s,
Alan WA4SCA
<-----Original Message----- <From: AMSAT-BB [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Jim Barbre <Sent: Friday, March 20, 2015 6:51 PM <To: AMSAT-BB@amsat.org <Subject: [amsat-bb] Overcoming desense on FO-29 < <Is the use of a down converter effective in overcoming desense on the <FO-29 70 cm downlink? The downconverter would convert 435 to 10 MHz. <Receiver is an SDR. (I have different ones for HF and for VHF.) <Also, what is the minimum recommended distance between linearly <polarized 2 m and 70 cm antennas on the same crossboom? Does it help <with desense if one is mounted horizontally and the other vertically? < <Thanks. <Jim Barbre <KB7YSY <_______________________________________________ <Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available <to all interested persons worldwide without requiring membership. Opinions expressed <are solely those of the author, and do not reflect the official views of AMSAT-NA. <Not an AMSAT-NA member? Join now to support the amateur satellite program! <Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb