Opinion regarding Coax upgrade.

zeppelin11

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Hello, I had recently purchased a PCTEL MYA8063 3 element Yagi antenna from The Antenna Farm. PCTEL MYA8063 - 800 MHz Yagi Antennas | The Antenna Farm Im monitoring 850mhz local Police, EMS, Fire. Gainesville Regional Utilities (GRUCom) Trunking System, Gainesville, Florida I am 15 miles from the tower im monitoring and the land is pretty flat. I have the antenna mounted on top of my RV roughly 4' above the roof pointed directly at the tower i wish to monitor. I used a jumper from the scanner to the antenna while on the roof and pointed the antenna toward the known location of the tower and secured it when i got the most bars. The Antenna is pointed up roughly 30 degrees. I have the elements pointed vertically. I am running 25' of RG8X Coax but I'm not sure how reputable the coax is. https://a.co/d/0y2uqKu When a transmission comes in i get 3-4 bars on my Uniden BCD436HP and half the time the transmission will be choppy and the bars will bounce. Sometimes i can clear it up by moving the radio a little to the left or right or forwards and backwards and on cold days/nights transmissions come in real well and not so well on warm days/ nights. I'm thinking if i upgraded the coax to LMR-400 by Times Microwave that i could clear up the choppy transmissions. What is your opinion? All opinions are welcomed and much appreciated.
 

mmckenna

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If the signal is fluctuating that much, it may mean there's something else going on other than coaxial cable deficiencies.
It is a simulcast system, and it's possible you are getting simulcast distortion.

You shouldn't need to aim the antenna "up". It should be flat, pointed at the horizon.
25' of RG-8x shouldn't be that big a deal for 800MHz. I've never heard of that brand, so it -could- be suspect, but I wouldn't expect a huge difference in performance by switching to LMR-400.
With simulcast distortion, sometimes the issue is too much signal.

You could try swinging the Yagi around a bit and see if you get better performance. Since you are 15 miles away, and a 3 element Yagi has a pretty broad beamwidth, it's entirely possible you are hearing more than one site. Aiming the antenna off a little bit, even if it results in less "bars", might make the difference.
 

zeppelin11

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Thank you for the clarification. There was a double sided sticky pad that came with the antenna, though im not completely sure what it is used for but i have a theory and correct me if I'm wrong but would i wrap this pad around the mast where i mount the antenna giving the mount bracket a more secure bite to the mast?
 

zeppelin11

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I'm located roughly where the green dot is located on the map and have the antenna pointing towards site 5. I see that site 9 is almost directly behind site 5 but that is probably 30+ miles away but nevertheless could 9 be interfering with my transmissions? I figure I'll point my antenna more towards the right of site 5 and play with the direction in that area. There is no other sites for this system to the right of 5. Screenshot_20230128_121601_Edge.jpg
 

mmckenna

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Thank you for the clarification. There was a double sided sticky pad that came with the antenna, though im not completely sure what it is used for but i have a theory and correct me if I'm wrong but would i wrap this pad around the mast where i mount the antenna giving the mount bracket a more secure bite to the mast?

It's probably coax seal tape.
 

davidgcet

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that sticky pad, what does it look like? ive seen them come with sealant to seal the connector but never with basically double sided tape to help secure it. as pointed out above you could be getting too much signal.
 

mmckenna

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I'm located roughly where the green dot is located on the map and have the antenna pointing towards site 5. I see that site 9 is almost directly behind site 5 but that is probably 30+ miles away but nevertheless could 9 be interfering with my transmissions? I figure I'll point my antenna more towards the right of site 5 and play with the direction in that area. There is no other sites for this system to the right of 5.

Entirely possible that is what is happening.

Pointing the antenna directly at the sites may be part of the issue, you may need to point it off to one side or another a bit to lower the signal strength from the towers you do not want to hear.
 

mmckenna

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I'd probably try pointing it off to the east of site 5. Again, strongest signal strength isn't your best choice here. Since it is a simulcast system, you want to hear just one of the sites.
 

zeppelin11

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This double sided sticky pad came from the antenna farm with the antenna i don't know what it could be used for. Too much signal in this case makes sense. I'll toy with it some time today and let yall know how it goes. I really appreciate yall taking the time to help me out with this.
 

mmckenna

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Once you get everything set up and working the way you want, do the following:

- Unscrew the coax at the antenna, make sure it is clean and 100% dry inside.
- Reconnect the coaxial connection. Tight, but not "grip of death" tight.
- Wrap the connection with electrical tape. Start at the connector end closest to the antenna. Wrap down the coax towards the radio. Overlap each pass 50%. When you get about 6 inches past the end of the connector, turn around and wrap back to the antenna. Tape should wrapped so it's tight, but not stretched. When you get to the end, cut the tape with scissors or a razor blade. Do NOT pull the tape so it breaks.
- Layer that coax sealer tape over the tape wrapped connection. Knead it in to all the spaces. Smooth out all edges so it looks like one solid piece. It should be a nice even covering from the antenna, covering the coaxial connector and covering the electrical tape.
- Wrap all that again with electrical tape, just like above.

That's the industry standard way to do it. If done correctly, that will protect the coaxial cable and connector for moisture ingress. Moisture inside the connector/coax will destroy it. I've done it this way for decades and I've never had a connection fail. In Florida with all the humidity and funky weather, you absolutely want to do this if you want your antenna and coaxial cable to last.
 

Fixitt

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industry standard

sorry to tangent off this thread

I am going to swap out RG6 coax for LRM400UF once the weather gets better. I bought a piece of 1” and 1 1/2 shrink wrap that has sealant inside. My plan was to use both. Should I return them or will they suffice?
 

mmckenna

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sorry to tangent off this thread

I am going to swap out RG6 coax for LRM400UF once the weather gets better. I bought a piece of 1” and 1 1/2 shrink wrap that has sealant inside. My plan was to use both. Should I return them or will they suffice?

If the heat shrink will slide over the connector and still seal tight around the cable, it should be fine.

Reason that's not well accepted in the industry is getting enough heat onto the tubing when up on a tower is rather difficult. If you can do it on the ground, it's much easier. There are 'cold shrink' kits that you can buy, but I'd stick with what you have.

Most of the high end connectors include heat shrink tubing to seal the joint where the cable enters the connector, as well as provide strain relief.
 

FKimble

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I'd point that antenna off to the west of tower #3. Then slowly move it toward #3 for best results. Pointing it towards # 5 will still have #2 in the pattern. Close as #2 is it could be double receiving both causing more grief. You only want one signal. It doesn't have to peg the needle, just one good clean tower is what you want.

Frank
 

ind224

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I would not have a yagi without a rotator or a means to move the antenna in real time while watching the CC decode. High winds, precip can be issues and the possibility of expansion / contraction with temp changes could indeed act like a cold solder joint.
Interesting you mention radio orientation matters; I knew the RS scanners did that and wonder if the SDS series does it as well.
 
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