Perhaps termination would help on the diplexer ... so far, I've kept it simple and just unplugged the unused antenna on the Arrow. It 'seems' to work OK when using the FT-1634.
Doug, N6UA
I actually dug up a Comet CF-4160J Diplexer (both Comet and Diamond call them "Duplexers") and swept its response with my Spectrum Analyzer, using the Low-Frequency and Common Port. I was also curious to find out if it mattered if the High-Frequency Port was terminated or not.
The bottom line is that this particular Diplexer would reduce the 2-meter 3rd harmonic by 55 dB, and had an insertion loss of 0.12 dB. And I confirmed that there was a small reduction performance if the High-Frequency Port was not terminated.
I would expect the performance of Diamond models would be similar and I will test one when I find one.
The actual report can be found here: http://wb4son.com/wpblog/?p=2828 (if the link is blocked, try WB4SON dot com and search for CF4160)
73, Bob, WB4SON
Hi!
Another option for diplexers as bandpass filters would be the MFJ diplexers. I use an MFJ-916B diplexer for my satellite station, and I saw a test comparing this with a Diamond MX-72 diplexer that was done a little over a year ago:
http://www.w4gso.org/news/comparing-duplexers-mfj-vs-diamond/
Summary: the MFJ diplexer outperformed the Diamond unit. Also, the MFJ diplexer costs about half of what you normally see for the equivalent Diamond or Comet units. And the MFJ-916B is made in Taiwan, not Mississippi.
73!
Patrick WD9EWK/VA7EWK http://www.wd9ewk.net/ Twitter: @WD9EWK
On Tue, Mar 28, 2017 at 10:51 PM, Bob [email protected] wrote:
I actually dug up a Comet CF-4160J Diplexer (both Comet and Diamond call them "Duplexers") and swept its response with my Spectrum Analyzer, using the Low-Frequency and Common Port. I was also curious to find out if it mattered if the High-Frequency Port was terminated or not.
The bottom line is that this particular Diplexer would reduce the 2-meter 3rd harmonic by 55 dB, and had an insertion loss of 0.12 dB. And I confirmed that there was a small reduction performance if the High-Frequency Port was not terminated.
I would expect the performance of Diamond models would be similar and I will test one when I find one.
The actual report can be found here: http://wb4son.com/wpblog/?p=2828 (if the link is blocked, try WB4SON dot com and search for CF4160)
73, Bob, WB4SON _______________________________________________
Thanks for that info Bob. Like Patrick, I also use the MFJ Diplexer (and spellcheck likes duplexer too) and have had good success with it. I will be ordering a terminator to correct my laziness (and maybe get a dB or two).
Appreciate your reply,
Doug, N6UA
On Mar 28, 2017, at 16:51 , Bob [email protected] wrote:
I actually dug up a Comet CF-4160J Diplexer (both Comet and Diamond call them "Duplexers") and swept its response with my Spectrum Analyzer, using the Low-Frequency and Common Port. I was also curious to find out if it mattered if the High-Frequency Port was terminated or not.
The bottom line is that this particular Diplexer would reduce the 2-meter 3rd harmonic by 55 dB, and had an insertion loss of 0.12 dB. And I confirmed that there was a small reduction performance if the High-Frequency Port was not terminated.
I would expect the performance of Diamond models would be similar and I will test one when I find one.
The actual report can be found here: http://wb4son.com/wpblog/?p=2828 (if the link is blocked, try WB4SON dot com and search for CF4160)
73, Bob, WB4SON
Douglas Tabor [email protected]
I too have an MJF I use with my Elk and it performs well. More recently I've been using an arrow with my FT-1634 and had no real problems with desense on Mode J. However, on Mode B I had all sorts of problems. FM wasn't so bad but on AO-7 it was practically useless unless I ran <1 watt. As a test I just threw on the arrow diplexer as an LPF and it gave marginal results. I tried many things to get rid of the problem going so far as to convert my 817's to N type rear connectors, hand built and sweeped a set of jumpers, you name it same problem. Eventually I decided to try a terminated diplexer. Not having anything on hand I desoldered the 70cm pigtail on the arrow diplexer and soldered (2) 100 ohm carbon film resistors in its place. Next AO-7 I gave it a shot and it worked like magic even when I was QRO at 5 watts.
With this lesson learned I believe the need for termination may be poorly represented by a bench test. I think that much of the UHF I was trying to block was actually making its way back through the BNC because of its proximity to the radiator. I now have it sealed and wire tied to the boom of my arrow and it works better than I ever expected the arrow diplexer could.
73
Mike Diehl AI6GS
On Mar 28, 2017, at 7:19 PM, Douglas Tabor [email protected] wrote:
Thanks for that info Bob. Like Patrick, I also use the MFJ Diplexer (and spellcheck likes duplexer too) and have had good success with it. I will be ordering a terminator to correct my laziness (and maybe get a dB or two).
Appreciate your reply,
Doug, N6UA
On Mar 28, 2017, at 16:51 , Bob [email protected] wrote:
I actually dug up a Comet CF-4160J Diplexer (both Comet and Diamond call them "Duplexers") and swept its response with my Spectrum Analyzer, using the Low-Frequency and Common Port. I was also curious to find out if it mattered if the High-Frequency Port was terminated or not.
The bottom line is that this particular Diplexer would reduce the 2-meter 3rd harmonic by 55 dB, and had an insertion loss of 0.12 dB. And I confirmed that there was a small reduction performance if the High-Frequency Port was not terminated.
I would expect the performance of Diamond models would be similar and I will test one when I find one.
The actual report can be found here: http://wb4son.com/wpblog/?p=2828 (if the link is blocked, try WB4SON dot com and search for CF4160)
73, Bob, WB4SON
Douglas Tabor [email protected]
Sent via [email protected]. 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://www.amsat.org/mailman/listinfo/amsat-bb
-
Bob -
Douglas Tabor -
dtaborï¼ estesvalley.net
-
Mike Diehl -
Patrick STODDARD (WD9EWK/VA7EWK)