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Old 12-Oct-2020, 2:51 PM   #1
eclipsme
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Combining other frequencies on 1 cable

I have started 'listening' to weather satellites using my SDR dongle.

Current setup is a DB8 roof mounted with a Wineguard LNA mounted on the mast feeding into a splitter in my office. 1 feed goes to the home theater PC and the other to the SDR. I use the SDR to monitor the quality of the TV signals and now am tuning in the 137Mhz range for weather sats.

With the current setup I am almost getting satellite signals but unreliably and need a different antenna for this purpose.

Can I combine the feed from the 137mhz antenna with the DB8 onto one coax?

Thanks!
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Old 12-Oct-2020, 11:11 PM   #2
Tower Guy
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If all of your TV channels are on UHF, (14-36); you may use a UVSJ to combine 137 MHz with the DB-8.
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Old 13-Oct-2020, 2:10 AM   #3
eclipsme
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Thanks. So 139 falls in the VHF range, right? I have no VHF at the moment but there are a couple that I would like to go after at some point, which would require an HVHF antenna. Could I use a VHF combiner for the 139mhz and for the HVHF, then into the UHF/VHF combiner?
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Old 13-Oct-2020, 4:44 AM   #4
OTAFAN
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Well, it's actually slightly above the Civil Aviation Band that you would listen to on a scanner, 108MHz to 136MHz; VHF radio spectrum. Here's a chart explaining. It's a bit out of date since Repack dropped UHF down to channel 36 from 69. The other link explains Aviation Radio Bands, global and space weather, etc. that may be of interest to you. All the best.....

http://www.hdtvprimer.com/ANTENNAS/TVfrequencies.html

https://www.smeter.net/spectrum/aviation.php

Last edited by OTAFAN; 13-Oct-2020 at 4:54 AM. Reason: additional
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Old 13-Oct-2020, 11:24 AM   #5
eclipsme
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Thanks for the additional info.
Yes, I am aware of the aviation band. What I meant to indicate is that the feed from the 139mhz antenna would connect to the VHF side of the combiner, but I was not clear. Sorry.

If later I also put up a HVHF antenna, would I use another combiner for the VHF and the 139 signals before combining with UHF?
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Old 13-Oct-2020, 2:20 PM   #6
Tower Guy
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I am not aware of any off the shelf combiners for the satellite band and high band VHF TV. You could try receiving satellite signals on a VHF TV antenna.

What is the channel of the TV station that you want to combine? That might suggest a combiner configuration that is not off the shelf.
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Old 13-Oct-2020, 2:40 PM   #7
eclipsme
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Quote:
Originally Posted by Tower Guy View Post
I am not aware of any off the shelf combiners for the satellite band and high band VHF TV. You could try receiving satellite signals on a VHF TV antenna.

What is the channel of the TV station that you want to combine? That might suggest a combiner configuration that is not off the shelf.
Tower Guy said, "If all of your TV channels are on UHF, (14-36); you may use a UVSJ to combine 137 MHz with the DB-8. " Googling for a 'UVSJ', this appears to be a VHF/UHF combiner, or am I wrong about that? I thought that a standard combiner might be able to combine high VHF with either the combined output of the UVSI or perhaps with the 139mhz signal before the UVSI.

Perhaps I am not understanding what the USVI is, though.

The VHF channels I am interested in are 11 and 12.
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Old 14-Oct-2020, 2:11 AM   #8
rabbit73
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Quote:
Originally Posted by eclipsme View Post
Tower Guy said, "If all of your TV channels are on UHF, (14-36); you may use a UVSJ to combine 137 MHz with the DB-8. " Googling for a 'UVSJ', this appears to be a VHF/UHF combiner, or am I wrong about that?

Perhaps I am not understanding what the USVJ is, though.
You can use a UVSJ to combine your UHF TV signals with your 137 MHz signals.



The UVSJ will pass 137 MHz signals on the VHF port while blocking any UHF signals picked up by the 137 MHz antenna. Also, it will pass UHF signals on the UHF port while blocking any 137 MHz signals picked up by the UHF antenna.

Quote:
I thought that a standard combiner might be able to combine high VHF with either the combined output of the UVSJ or perhaps with the 139mhz signal before the UVSJ.
If you mean a splitter in reverse as a "standard combiner," that will probably not work. The same signals from each antenna will interfere with each other when they reach the "combiner."
Quote:
The VHF channels I am interested in are 11 and 12.
You would need an expensive filter combiner to have VHF TV, UHF TV, and 137 MHz on one downlead. I suggest a separate coax downlead for the 137 MHz antenna.
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File Type: png RS15-2586UVSJ FreqResp4.png (117.4 KB, 93 views)
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Last edited by rabbit73; 14-Oct-2020 at 2:19 AM.
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Old 14-Oct-2020, 1:10 PM   #9
eclipsme
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Quote:
Originally Posted by rabbit73 View Post
You can use a UVSJ to combine your UHF TV signals with your 137 MHz signals.



The UVSJ will pass 137 MHz signals on the VHF port while blocking any UHF signals picked up by the 137 MHz antenna. Also, it will pass UHF signals on the UHF port while blocking any 137 MHz signals picked up by the UHF antenna.


If you mean a splitter in reverse as a "standard combiner," that will probably not work. The same signals from each antenna will interfere with each other when they reach the "combiner."

You would need an expensive filter combiner to have VHF TV, UHF TV, and 137 MHz on one downlead. I suggest a separate coax downlead for the 137 MHz antenna.
OK, I think I understand now. Thanks!

These UVSJ combiners have become a bit of a scarce commodity, it seems. I did find this:
https://www.amazon.com/Weatherproof-...2676652&sr=8-1

Claims .5db loss where others are 1.5db. Also passive dc pass through on both ports. Some others were only on VHF side, which doesn't work for me.

Thanks, everybody, for the pointers!
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