I've never had a desense problem operating 5w into linear satellites U/V or V/U with a 817/d74. I would suspect 817/817 would be the same.
For grin's I put a diplexer and even a mini circuits LPF inline on both U/V antenna connections and noticed zero difference in being able to RX then without them
A.J. AJ2I
From: David Spoelstra via AMSAT-BB [email protected] Sent: Monday, September 4, 2023 2:40 PM To: Erik Eitel [email protected] Cc: AMSAT BB [email protected] Subject: [AMSAT-BB] Re: Linear vs FM Sats
When operating v/u where should the filter go? 70cm side. Does it matter if I am operating FM or linear as far as desense is concerned? If you are having desense, you are having it regardless of the mode. You may not notice it with the FM birds because their transmitters are so strong and because of the FM capture effect. Can I use the diplexer in the Arrow antenna as a filter? Yes, however there are several issues with it: 1. It can only handle 10 watts. 2. I don't know how good the separation is with regard to the Comet (or others) in the AMSAT article Ray KN2K referred you to. 3. It has a 2m pigtail that might (probably?) pickup some of the 2m energy transmitted and feed it back to the 70cm side which will desense it and defeat what you are trying to accomplish like the article says.
-David, N9KT
On Mon, Sep 4, 2023 at 1:10 PM Erik Eitel via AMSAT-BB <[email protected]mailto:[email protected]> wrote: I am fairly new to chasing satellites. I have the FM sats down fairly well and I am trying to get into the linear birds.
Here’s my set up:
-Arrow antenna with diplexer mounted on bike repair stand. -ICOM 2730a (I used this with great success on the FM sats) -2 Yaesu FT-818 (replacing the 2730 for all sats)
I’ve read many articles and visited many web pages but I am confused a bit with desense. When operating v/u where should the filter go? On the 2m side or the 70cm side? Does it matter if I am operating FM or linear as far as desense is concerned? I have no problem hearing myself while operating FM v/u sats using the FT-818s. Can I use the diplexer in the Arrow antenna as a filter?
Still trying to get the hang of the linear birds.
Thanks for the help.
73 Erik K2ERK - FN20
-----------------------------------------------------------
Sent via AMSAT-BB(a)amsat.orghttp://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. Acceptable Use and Privacy Policies available at https://www.amsat.org/about-amsat/
View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/[email protected] To unsubscribe send an email to amsat-bb-leave(a)amsat.orghttp://amsat.org Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org