Dave, not referring to your problem, do you notice a big difference when changing polarity? Wondered if it was worth the cost and effort to add polarity to my M2 antennas. Thanks for the info. Mike
-----Original Message----- From: Ant Lefebvre anthony.lefebvre@gmail.com To: Dave Julian ddjulian54@yahoo.com Cc: AMSAT BB amsat-bb@amsat.org Sent: Tue, Feb 8, 2022 12:06 pm Subject: [AMSAT-BB] Re: IC-9700 and PS 70 not playing well together
Dave, I use a comet duplexer CF-4160N to avoid desense issues. It acts as a bandpass filter with 60dB of rejection from your 2m TX. The dummy load is on there, because I read somewhere it acts better with one attached since it would expect to be connected to something vs open. https://www.dxengineering.com/parts/cma-cf-4160n
73 -Ant NU1U
On Tue, Feb 8, 2022 at 11:41 AM Dave Julian via AMSAT-BB amsat-bb@amsat.org wrote:
Just got a new SSB SP 70 preamplifier for my IC-9700 andhaving an issue with working 435 RX satellites like RS-44. The amplifier works fine but I am getting terrible overloaadfrom the 2M TX signal. It causes the OVF light to come on and very distorted audio. I have lowered the RX gain and TXpower on the IC-9700 but by that time it kind of defeats the purpose of a preamplifier. My set-up is an M2 2MCP22 with fixedpolarity on 2m and a 436CP30 with the PS-70Cm polarity switch for UHF. I have about a 200' run on LMR-400 to the base of the towerwith lightning arrestors then about 40' of RG-213 to the antennas. For testing I have the Sp 70 preamplifier temporarlyinstalled at the base of the tower. No preamplifier for 2m. Power to the preamplifier is over the coax from the IC-9700.I am looking any any suggestions on sorting this out. I have removed the PS 70 at this point to avoid damage theradio or preamplifier. ThanksDave WB9YIG -----------------------------------------------------------
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