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

[ASTRO_Man]

Here is what I will do first before buying an amp:
Get Attenuators: 3db and 6db
Get FM Trap

How does this sound to start?

 

[737mech]

Yes try the fm trap first. RS sells this one https://www.ebay.com/p/RadioShack-FM-Trap-75-Ohm-Coax-TV-Connector-1500024/2255304113 it's not awesome. The Fm Filter from RTL/SDR is awesome. https://www.amazon.com/Broadcast-FM-Block-Filter-88/dp/B01LE9LRPM you'll need adaptors but it's worth it. PM me for comments I'm done posting here. Don't want to invite others that think I'm FOS. I'm trying to help from experience only.

 

[ASTRO_Man]

Sorry guys, I am just new to this whole thing. Here is what I will do first, without an amp (attenuators are cheap so I will just get them):

 

[Ubbe]

If you want to start with that setup then do not use the attenuators for now and get a good FM trap filter that do not attenuate all frequencies, not the RS one. The RTL-SDR one that 737mech suggest are excellent. But do not forget adaptors or pigtails to be able to connect it.
https://www.amazon.com/s/ref=nb_sb_noss_2?url=search-alias=aps&field-keywords=sma+adaptor
https://www.amazon.com/s/ref=nb_sb_noss?url=search-alias=electronics&field-keywords=pigtail+sma

It will probably do nothing for your 800MHz reception, scanners 800MHz frontend filters take care of FM broadcast signals, but might improve your VHF, but as I understand that was already ok.

I really cant see any other solution than spending the $$$ to get that prefered equalized pre-amp, or similar amp, to improve 800Mhz or to a reduced cost, and reduced performance, the one you found.
With the EQ pre-amp you might not need the FM trap filter, just the attenuator, so the cost might be the same as the cheaper amp with an FM trap filter.

As you intend to have the amplifier inside the house you could get a much better specification amp at a reduced cost like this one: https://www.ebay.com/itm/Ultra-Line...MHz-2GHz-LNA-Gain-20dB-NF-0-5-dB/282560489483 That company also have FM trap filters and connectors.

/Ubbe

 

[ASTRO_Man]

I am taking 737mech's advice and doing the FM Trap first to see what happens. I assume it can't do any harm to 800MHz, and I listen to airband too so it will at least work with that. It's coming on Amazon Prime Sunday, I will let everyone know how it works once installed.

 

[Ubbe]

Try and make some reference notes before the install from ground stations in airband how well you can hear them, like the tower or ATIS transmissions. Airplanes on route are difficult to use as a reference.

/Ubbe

 

[ASTRO_Man]

Try and make some reference notes before the install from ground stations in airband how well you can hear them, like the tower or ATIS transmissions. Airplanes on route are difficult to use as a reference.

/Ubbe

That’s exactly what I did; and the ATIS sounds terrible - so that’s my benchmark to see. Would it be possible that the FM Trap can help my 800MHz experience? I know it’s a life changing experience on airband, but what about others or 800MHz? Can it hurt others?

 

[Ubbe]

I'm sitting 6 miles from a tower with four 60kW FM transmitters and six 40kW TV transmitters and don't see any changes in the airband using several different FM trap filters to my Uniden scanners. It hits me in the 70Mhz-80Mhz range. It's very individual how broadcast and other transmitters affects your scanner monitoring.

/Ubbe

 

[ASTRO_Man]

So...I installed the FM Trap today and the results are exactly the same - nothing changed. I listened to the ATIS before I installed and after I installed with no improvement whatsoever. Unusual?

 

[Ubbe]

Your antenna isn't big enough to cover the lower frequencies of airband and FM broadcast and the signal levels are low enough that the scanners filters can handle it.

/Ubbe

 

[trp2525]

In addition to the Laird MBCN ground plane kit with N connector termination that I previously referenced in my post #3 above for $29.95 plus shipping (https://www.theantennafarm.com/catalog/laird-technologies-mbcn-7531), I recently came upon another different brand ground plane kit with N connector termination on eBay. Per the eBay listing it's the Averonic GPKN and it currently sells for $26.95 with FREE shipping included: https://www.ebay.com/itm/BASE-GROUND-PLANE-KIT-NMO-to-N-CONNECTOR-VERSION/252351313366.

The two products look very similar in design. I did, however, pick up on the fact that the 4 included radials with the Laird MBCN are 22.5" long while the 4 included radials with the Averonic GPKN are 20.5" long. Note that Laird recommends cutting their 4 22.5" radials down to 8" for 406-512 MHz use: http://www.theantennafarm.com/Brochures/mbc_mbc800installinstructions.pdf

 

[AK4FD]

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).

Personally, I prefer Mini-UHF connectors. They’re rated for a max up to 2.5 GHz according to AmphenolRF’s chart, and most Motorola radio mobiles use them. PL-259’s have always been horrible in my experience for anything above VHF. I’ve always had really good luck with Mini-UHF connections that I’ve used, especially when dealing with P25 trunked 700/800 MHz digital systems. Just my .02¢