I am still having desense on my UHF downlink on the IC-9700. Antenna is a 30 element M2 CP Yagi with SSB Preamp at the antenna. I have yet to check connections at the end for any problems, but will do so. Connectos are all Type N on system. Is there any better option than the Comet CF-416C diplexer to help or even eliminate the 2M uplink from desensing the 70CM downlink ? I would have to weatherize it to ensure longlife, etc. Perhaps there is a sealed inline filter that would handle the capability of the radio which is 75 watts out on 70CM. Anyone with info pleae share with me. Tnx Jerry KJ4EU
Hi Jerry, you might consider putting one of these in the shack. Very well made and seems to help at my QTH.
https://www.ocicom.com/index.php/amateur-radio/products/2-meter-bandpass-fil...
73, Mark N8MH
On Fri, Jun 24, 2022 at 10:13 AM BeetleJerald Oliver [email protected] wrote:
I am still having desense on my UHF downlink on the IC-9700. Antenna is a 30 element M2 CP Yagi with SSB Preamp at the antenna.
I have yet to check connections at the end for any problems, but will do so.
Connectos are all Type N on system.
Is there any better option than the Comet CF-416C diplexer to help or even eliminate the 2M uplink from desensing the 70CM downlink ?
I would have to weatherize it to ensure longlife, etc. Perhaps there is a sealed inline filter that would handle the capability of the
radio which is 75 watts out on 70CM. Anyone with info pleae share with me.
Tnx
Jerry KJ4EU
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Hi Jerry,
This is the one that I use that’s quite effective.
http://www.parelectronics.com/sat-amateur.php
73 Curt N0GVK
On Jun 24, 2022, at 9:13 AM, BeetleJerald Oliver [email protected] wrote:
I am still having desense on my UHF downlink on the IC-9700. Antenna is a 30 element M2 CP Yagi with SSB Preamp at the antenna.
I have yet to check connections at the end for any problems, but will do so.
Connectos are all Type N on system.
Is there any better option than the Comet CF-416C diplexer to help or even eliminate the 2M uplink from desensing the 70CM downlink ?
I would have to weatherize it to ensure longlife, etc. Perhaps there is a sealed inline filter that would handle the capability of the
radio which is 75 watts out on 70CM. Anyone with info pleae share with me.
Tnx
Jerry KJ4EU
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On 6/24/22 09:12, BeetleJerald Oliver wrote:
I am still having desense on my UHF downlink on the IC-9700. Antenna is a 30 element M2 CP Yagi with SSB Preamp at the antenna.
Your de-sense problem is compounded by the gain of the SSB pre-amp (LNA). A suitable filter inserted between the antenna and LNA would probably fix the issue.
N0GVK's suggestion of http://www.parelectronics.com/sat-amateur.php is an example of something that would work. A simple diplexer, such as the Comet, would also work.
The problem with adding it in the shack, as N8MH suggests, is that you've already amplified the problem by the gain of the LNA. Indeed, your LNA may be overloaded by your 2m transmit signal and the filter in front of it will eliminate that.
TANSTAAFL: Insertion loss will increase. However, we're not EME, so a few tenths of NF increase shouldn't matter.
--- Zach N0ZGO
Also have a look at https://www.dk3wn.info/wp/equipment/mode-j-filter/
On 24-06-2022 16:12, BeetleJerald Oliver wrote:
I am still having desense on my UHF downlink on the IC-9700. Antenna is a 30 element M2 CP Yagi with SSB Preamp at the antenna.
I have yet to check connections at the end for any problems, but will do so.
Connectos are all Type N on system.
Is there any better option than the Comet CF-416C diplexer to help or even eliminate the 2M uplink from desensing the 70CM downlink ?
I would have to weatherize it to ensure longlife, etc. Perhaps there is a sealed inline filter that would handle the capability of the
radio which is 75 watts out on 70CM. Anyone with info pleae share with me.
Tnx
Jerry KJ4EU
On 6/24/22 11:27, PE0SAT | Amateur Radio via AMSAT-BB wrote:
Also have a look at https://www.dk3wn.info/wp/equipment/mode-j-filter/
Or, for those who don't read German:
https://www-dk3wn-info.translate.goog/wp/equipment/mode-j-filter/?_x_tr_sl=a...
--- Zach N0ZGO
On 6/24/22 09:33, Zach Metzinger wrote:
A simple diplexer, such as the Comet, would also work.
If you're a DIY-er type, this diplexer can be build easily:
This design is for 10W, but the component ratings (not values) could be changed to handle more power. The author notes this in the design section.
--- Zach N0ZGO
Hello, In this Instructable manual another simple diplexer is detailed, it is the one I currently use, it also works up to 10 w with the possibility of improving its capacity
https://www.instructables.com/Antena-Para-Sat%C3%A9lites-LEO-Radioaficionado...
TI3IES - Ignacio
El lun, 27 jun 2022 a las 9:03, Zach Metzinger ([email protected]) escribió:
On 6/24/22 09:33, Zach Metzinger wrote:
A simple diplexer, such as the Comet, would also work.
If you're a DIY-er type, this diplexer can be build easily:
This design is for 10W, but the component ratings (not values) could be changed to handle more power. The author notes this in the design section.
--- Zach N0ZGO
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On Mon, Jun 27, 2022 at 8:02 AM Zach Metzinger [email protected] wrote:
If you're a DIY-er type, this diplexer can be build easily:
You can get boards for this design from OSH Park thanks to KW4FB:
http://kw4fb.com/micro-diplexer/
There's also a BOM for Mouser. As Zach said, it's an easy build.
Martin. KD6YAM
This design is for 10W, but the component ratings (not values) could be changed to handle more power. The author notes this in the design section.
--- Zach N0ZGO
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On Mon, Jun 27, 2022 at 8:02 AM Zach Metzinger [email protected] wrote:
If you're a DIY-er type, this diplexer can be build easily:
You can get boards for this design from OSH Park thanks to KW4FB:
http://kw4fb.com/micro-diplexer/
There's also a BOM for Mouser. As Zach said, it's an easy build.
Martin. KD6YAM
This design is for 10W, but the component ratings (not values) could be
changed to handle more power. The author notes this in the design section.
--- Zach N0ZGO
Sent via AMSAT-BB(a)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/
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Tnx to everyone who responded to my Email concerning mode J filter. I went ahead and purchased one from Par Electronics. Will send an update to the BB when it arrives and is installed. 73 Jerry KJ4EU On Friday, June 24, 2022, 09:13:34 AM CDT, BeetleJerald Oliver [email protected] wrote:
I am still having desense on my UHF downlink on the IC-9700. Antenna is a 30 element M2 CP Yagi with SSB Preamp at the antenna. I have yet to check connections at the end for any problems, but will do so. Connectos are all Type N on system. Is there any better option than the Comet CF-416C diplexer to help or even eliminate the 2M uplink from desensing the 70CM downlink ? I would have to weatherize it to ensure longlife, etc. Perhaps there is a sealed inline filter that would handle the capability of the radio which is 75 watts out on 70CM. Anyone with info pleae share with me. Tnx Jerry KJ4EU
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participants (8)
-
BeetleJerald Oliver -
Curt Pikschus -
Ignacio Granados Vega -
Mark L. Hammond -
Martin Cooper -
Martin Cooper -
PE0SAT | Amateur Radio -
Zach Metzinger