Did I Order The Wrong NMO Ground Plane? (UHF or N?)

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ASTRO_Man

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Here’s my tentative setup:

Larsen Triband 150/450/800 on NMO Ground Plane. Use PL-259 to F adapter and run RG6 Quad Shielded cable to a UG2802 drop amplifier to 5 other scanners. The scanners will use 6’ F cable and use F to BNC adapters to connect.

Here’s my dilemma, my Ground Plane kit arrives tomorrow but it has a UHF connector on it. From my research, the UHF connector is not liked by many and has loss above 500MHz. I will be monitoring several 800MHz systems with this antenna.

Should I return this NMO Ground Plane with a UHF connector and get one with an N connector instead? Will the difference in reception be that much, considering I will immediately be using an F connector to run with RG6 cable? I want to make sure I can have the most reliable setup. Thank you.
 

jonwienke

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You'll lose more signal attaching 75-ohm coax between two 50-ohm devices through multiple adapters on each end than the difference between an N connector and SO-239. Keep the ground plane you have, get some decent 50-ohm coax like LMR-400 instead of RG-6 so that the entire signal path is 50-ohm and you'll be better off overall. Just make sure you thoroughly seal the SO-239 connector to prevent moisture ingress.
 

trp2525

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Here’s my tentative setup:

Larsen Triband 150/450/800 on NMO Ground Plane. Use PL-259 to F adapter and run RG6 Quad Shielded cable to a UG2802 drop amplifier to 5 other scanners. The scanners will use 6’ F cable and use F to BNC adapters to connect.

Here’s my dilemma, my Ground Plane kit arrives tomorrow but it has a UHF connector on it. From my research, the UHF connector is not liked by many and has loss above 500MHz. I will be monitoring several 800MHz systems with this antenna.

Should I return this NMO Ground Plane with a UHF connector and get one with an N connector instead? Will the difference in reception be that much, considering I will immediately be using an F connector to run with RG6 cable? I want to make sure I can have the most reliable setup. Thank you.

Personally I would return the NMO ground plane kit with the UHF connector and get the NMO ground plane kit with the N connector instead. At the Antenna Farm the price is the same at $29.95 for either the Laird MBC with the UHF connector or the Laird MBCN with the N connector: https://www.theantennafarm.com/cata...e-kits-483/hf-vhf-mobile-antenna-to-base-484/

According to an RF connector frequency range chart on the Amphenol website (https://www.amphenolrf.com/frequency-range-chart/), the maximum frequency listed for a UHF connector (PL-259/SO-239) is 300 MHz. For comparison an F-Type connector has a listed maximum frequency of 1 GHz (1,000 MHz) and an N-Type connector has a listed maximum frequency of 11 GHz (11,000 MHz). Amphenol is a very respected name in the RF connector industry so I trust the information that they display on their website.

For further information on the inadequacies of the UHF connector at higher frequencies like 800 MHz, go to the Telco Antennas website (https://www.telcoantennas.com.au/site/guide-antenna-cables-connectors) which states the following:

"UHF series are a variable impedance connector designed for low frequency operations 600KHz to 300MHz. This very large connector is used almost exclusively for radio and UHF applications. The low cost design of UHF connectors often results in impedance varying between 30-40Ω causing significant reflections above 300MHz. Despite this, the connector remains popular with CB/UHF (477MHz) users."

Sticking with your original plan of using RG6 Quad Shield coax, you could use an F-to-N adapter (https://www.theantennafarm.com/catalog/enp-26-8020-5908) at the antenna instead of the F-to-PL-259 adapter that you were going to use with the UHF connector. At the scanner ends I would terminate your 6-foot RG6 cables with a compression-type BNC connector instead of using an F connector with an F-to-BNC adapter. Look for Radio Shack 278-033 RG6 BNC compression connectors (or equivalent) to terminate your RG6 coax (https://www.ebay.com/itm/RADIO-SHAC...BNC-CONNECTOR-6-PACK-P-N-278-033/272755771926).
 

trp2525

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...Let's suppose I get LMR400 cable. Could I get 50 ohm F-connectors to fit into the amp?...

Field Components, Inc. will make up a custom cable assembly of true/genuine Times Microwave LMR400 in whatever length you need and will terminate the ends with whatever connectors you need. They have MANY connectors listed on their website drop down lists including N male, F male, UHF male, BNC male, etc. If you are so inclined you can contact them for availability of exactly what you need and a custom cable assembly quote: https://fieldcomponents.com/LMR-400-Cable-Assemblies-Times-Microwave-LMR400.html
 

737mech

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F connectors

Before you order LMR with f consider BNC. You might be adding an FM trap in the future? LMR to trap to splitter amp. You could always try it out first with adaptors?
 

mmckenna

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Yeah, I'd agree. I wouldn't put in LMR-400 with F connectors. While I'm sure they work well, keeping your options open down the road would be wise. Where possible use N connectors. Ideally you shouldn't be connecting LMR-400 directly to a radio, using jumpers is SOP. Keeping with a standardized 50Ω connector that can be pushed into transmit duty down the road if your needs change would be valuable.
 

trp2525

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...Here’s my dilemma, my Ground Plane kit arrives tomorrow but it has a UHF connector on it. From my research, the UHF connector is not liked by many and has loss above 500MHz. I will be monitoring several 800MHz systems with this antenna.

Should I return this NMO Ground Plane with a UHF connector and get one with an N connector instead?...

...Let's suppose I get LMR400 cable. Could I get 50 ohm F-connectors to fit into the amp?...

Out of curiosity what did you decide to do? Did you keep the ground-plane kit with the UHF/SO-239 connector or did you return it and get a ground-plane kit with an N connector?

Regarding the coax, did you stick with your original plan of using RG6 quad-shield or did you upgrade to the LMR400 from the ground-plane kit to your distribution amplifier?

Lastly how did you terminate the 6-foot coax jumpers at the scanner ends? Did you use BNC adapters as originally planned or did you terminate the coax with BNC connectors?
 

ASTRO_Man

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Good timing for your reply, I just finished this project today. I ended up using rugged RG6 CATV cable (my father had a huge spoll of it in his garage). Pretty sure the stuff was not quad shield, but it was very durable (made for being run underground I believe).

I returned the UHF kit and get the N connector instead, not sure what difference it would’ve made but I wanted to do this project right the first time.

I only used one adapter for this project, and that was a F to N adapter for the antenna base. I ordered a crimp on N male connector, but the sleeve couldn’t fit onto the cable so I just ordered the adapter. All other connections were terminated with an F or BNC crimp connector. Keep in mind, this antenna is going into a drop amp (UG2802 specifically). I’ve also used F 90° adapters to ease the load on the connectors, but so far I don’t think the adapters are causing any noticeable loss.

I run 4 online feeds, so I made 4 short cables going from the amp to the scanners (this is in the attic). Then I fished s good amount of wire down the wall to my office, for my desktop scanner. I used an F connector wallplate for this extension.

Overall, I am pleased with the performance for this setup. It isn’t amazing, but it’s a very big improvement and I’m only using one all band antenna; so I don’t have to switch antennas for my listening needs. I can tell that I have more loss in the office scanner than the attic scanners because of the extra wiring to go down the wall, into the wallplate, a 90° adapter, and another 15’ of RG6. I can tell because the 800 MHz signal for my town’s system is somewhat stronger upstairs on a scanner with a shorter cable than the office scanner. Nonetheless, I’m pleased with the setup and I can hear a significant amount of radio traffic than what I was getting before.

If anyone else has any suggestions, please let me know.
 

Ubbe

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The UG2802 is a zero gain amp with 5dB noise figure so it is adding noise and not compensating for any cable loss. It is supposed to be used with an antenna amplifier with less noise figure at the mast that boost the signal level before entering this distribution splitter.

If you feel you need to improve your reception from your broadband antenna then look into adding a mast preamp. If you like the Electroline models you could get something like their EDA100-EQ7 or preferable the EDA101 package that includes a power inserter. It is an equalised amp that have higher gain on higher frequencies to properly compensate for cable loss. It's $50 on Amazon but there are others to choose from. Look for the ones that have 3dB or less in NF noise figure.

/Ubbe
 

ASTRO_Man

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The UG2802 is a zero gain amp with 5dB noise figure so it is adding noise and not compensating for any cable loss. It is supposed to be used with an antenna amplifier with less noise figure at the mast that boost the signal level before entering this distribution splitter.

If you feel you need to improve your reception from your broadband antenna then look into adding a mast preamp. If you like the Electroline models you could get something like their EDA100-EQ7 or preferable the EDA101 package that includes a power inserter. It is an equalised amp that have higher gain on higher frequencies to properly compensate for cable loss. It's $50 on Amazon but there are others to choose from. Look for the ones that have 3dB or less in NF noise figure.

/Ubbe

Where in the antenna cable should this be inserted? Can this be inserted closer to the antenna or can I insert it closer to the UG2802? So this would be used on the antenna cable going into the UG2802.
 

Ubbe

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Where in the antenna cable should this be inserted? Can this be inserted closer to the antenna or can I insert it closer to the UG2802? So this would be used on the antenna cable going into the UG2802.
Yes, insert the pre-amp anywhere between the UG and antenna, where you feel it is easiest to do.
Preferable it should sit as few feet as possible from the antenna and it is powered thru the coax so it doesn't need any other cables connected to it.
I would use a watertight box with just a couple of feet of coax to the antenna.

/Ubbe
 

ASTRO_Man

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Yes, insert the pre-amp anywhere between the UG and antenna, where you feel it is easiest to do.
Preferable it should sit as few feet as possible from the antenna and it is powered thru the coax so it doesn't need any other cables connected to it.
I would use a watertight box with just a couple of feet of coax to the antenna.

/Ubbe

I’ll buy this one tonight unless I hear from someone otherwise: PCT 1-PORT BI-DIRECTIONAL CABLE TV HDTV AMPLIFIER SIGNAL BOOSTER WITH PASSIVE RETURN PATH https://www.amazon.com/dp/B000F28DP2/ref=cm_sw_r_cp_api_dlORAb279P4RK

I’ll keep it inside, and as close to the hole for the cable as possible.

With this amplifier, do you suggest I put in an FM filter too? How would I know if I need one?
 

737mech

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Fm trap

Between ug2802 and antenna inline fm broadcast filter. Worth a try, even if you try the cheap RS one. I found a good one at amazon rtlsdr broadcast fm filter. But then you need sma adaptors. Also a really good fm trap can be found at parelectronics.com. Go to fmfool.com type in your town, lots of problems in Greenwich. You need the fm trap.
 
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Ubbe

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Not the most ideal preamp, it amplifies 15dB at lower frequencies and less at 800MHz, maybe not the best as the attenuation in coax and splitter are the most at 800MHz and lowest at 100MHz. You probably will need that FM trap filter as the signal from FM broadcaster will be high into your scanners.

I recommend getting a 3dB and a 6dB attenuator to reduce the signal between the preamp and UG to avoid overloading a scanners input. Either use 3dB or 6dB or both together depending of the result you get when monitoring a weak signal. https://www.amazon.com/3db-Coax-Cable-Attenuator-each/dp/B0013L69D2 https://www.amazon.com/6db-Attenuator-Pad-1-each/dp/B0013L48XA

/Ubbe
 

ASTRO_Man

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Not the most ideal preamp, it amplifies 15dB at lower frequencies and less at 800MHz, maybe not the best as the attenuation in coax and splitter are the most at 800MHz and lowest at 100MHz. You probably will need that FM trap filter as the signal from FM broadcaster will be high into your scanners.

I recommend getting a 3dB and a 6dB attenuator to reduce the signal between the preamp and UG to avoid overloading a scanners input. Either use 3dB or 6dB or both together depending of the result you get when monitoring a weak signal. https://www.amazon.com/3db-Coax-Cable-Attenuator-each/dp/B0013L69D2 https://www.amazon.com/6db-Attenuator-Pad-1-each/dp/B0013L48XA

/Ubbe

I am getting 150MHz VHF just fine, but 800MHz is struggling. Should I get the attenuators and do without the amp? Or get the attenuator and the amp too? Right now I have attenuators, an amp, and a FM trap in my radar. Thanks for all the input
 

kruser

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What is the Noise Figure on this PCT amp?
The 15dB gain along with a high noise figure may do more harm than any benefit the amp provides. Attenuators will lower the high gain but a high noise figure can kill weak digital signals.

For the attenuators, yes, you would want those along with this amp.

Ubbe's reasoning is sound in that the amp has a fairly high output so you will want to tame that down with attenuators.
I also agree with Ubbe and advise a decent FM trap. Amps like these will most certainly cause desense or overload from FM broadcast stations.

Your two radio models you have listed are made by GRE. I'm not sure about the 528 but the 106 is notorious for overload from FM Broadcast stations. GRE did a very poor job with filtering the 88 to 108 MHz FM band.
In my experience, the Whistler models exhibit the same poor FM band filtering with their TRX-1 and 2 models.
A decent FM trap goes a long way in fixing overload issues with the GRE designs.
 

Ubbe

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Take out the pre-amp, Antenna-Fm trap-UG2802-scanners. That's it, post a reply how that works.

Not a good advice. The UG2802 are a distribution splitter with a noise generator at low signal levels and zero gain.

You definitly need a pre-amp with this splitter. The RS FM trap filter attenuates 5-6dB on all frequencies which might not be so bad in this configuration and the 3-6dB inline attenuators might not be needed, but the cost is minimal so I recommend getting them.

/Ubbe
 

737mech

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I'm just helping him test things out. I use the EDA amp as well. I have no requirement for a pre amp in my setup. Just trying other things for the setup. I know the math makes sense but the gre scanners and his position in fm hell needs help. Amping up not going in the right direction. Better fm trap needed. Maybe trade that ug2802 in for a UG2800? +4db gain per port.
 
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