Coil, uncoil, or cut the coax

[banjo5stringleon]

Long story short. The antenna I installed in the attic was being used by the tripod. The tripod became part of the antenna. I hung the antenna from the rafters and it did better. I have extra coax still. Can I coil it up and get it off the floor, or cut part of the 50' off. Will that hurt reception? Does anyone know what would happen?

 

[mmckenna]

All coax cable has some amount of loss.
The higher the frequency, the more the loss.
The longer the cable, the more the loss.

It's always a good idea to cut it to the length you need.

 

[12dbsinad]

Get rid of the "extra", it's not going to hurt.

Countless times I've seen full length mobile antenna cable kits (RG58 type) with all 17' coiled up, even though 8-10 feet are being used. At high frequencies like 700/800 that represents a lot of unnecessary loss.

 

[banjo5stringleon]

All coax cable has some amount of loss.
The higher the frequency, the more the loss.
The longer the cable, the more the loss.

It's always a good idea to cut it to the length you need.

Thanks for the help on the coax!

All coax cable has some amount of loss.
The higher the frequency, the more the loss.
The longer the cable, the more the loss.

It's always a good idea to cut it to the length you need.

Thank you for your help!

 

[banjo5stringleon]

Get rid of the "extra", it's not going to hurt.

Countless times I've seen full length mobile antenna cable kits (RG58 type) with all 17' coiled up, even though 8-10 feet are being used. At high frequencies like 700/800 that represents a lot of unnecessary loss.

Thanks for the help

 

[AB5ID]

Some questions would be how much extra cable would be eliminated, what type of cable, what frequencies do you want to listen to , and how comfortable are you with replacing connectors?
Shorter is always better but you can can reach a point of diminishing returns and inconvenience.

 

[banjo5stringleon]

AB5ID
My brother-in-law also talked about cutting to much off. We will be careful as much as we can. There is a lot lying up on the floor because where the radio is downstairs, it's just about below the antenna in the attic. Plus if we had to, we could always splice back together. But we really don't want that either. There are different routs we can take from the suggestions of others. Thanks for your input.

 

[banjo5stringleon]

/Ubbe
I’m thinking on going ahead and cut. We’re going to splice

All coax cable has some amount of loss.
The higher the frequency, the more the loss.
The longer the cable, the more the loss.

It's always a good idea to cut it to the length you need.

/UBBE
You’ve helped with your comments about cutting the cable. I do have another question for you. I was looking at antenna amplifiers. Since there on the market that means they must work. Can you tell me of some good ones to use for your scanner antenna? I noticed just looking around that I didnt really see any made for scanner antennas per say. But for TV with VHF and UHF. Thanks

 

[banjo5stringleon]

Get rid of the "extra", it's not going to hurt.

Countless times I've seen full length mobile antenna cable kits (RG58 type) with all 17' coiled up, even though 8-10 feet are being used. At high frequencies like 700/800 that represents a lot of unnecessary loss.

What are some good antenna amplifiers that you know of. I’ve been shopping and they’re mostly if not all for TV. Although there set for UHF and VHF. Which I’m guessing all antenna are the same, mostly ? Thanks in advance.

 

[Ubbe]

Can you tell me of some good ones to use for your scanner antenna?

Any one that uses the PGA103+ are good ones. The diffirence between them are if they come as a circuit board with connectors or if they are enclosed in a metal box. Some can be powered from USB, that's good for indoor use, or from the coax which is good for outdoor use.

I bought a cheap amplifier from China with unknown components and that had so much internal noise that it couldn't be used with any scanner without making the signal worse. Not all amplifiers are suited for scanner use.

What is crucial are that you use a variable attenuator to reduce the signal level from the amplifier before it reaches any scanner. Most amplifiers have a 10-20dB gain that are too much for any scanner without it loosing sensitivity and in many cases create intermodulation and overload issues. Uisng the variable attenuator you listen to a weak analog signal and adjust for best signal. It will be a sweat spot where the noise is at the lowest and if the signal are attenuated less or more it will in both cases increase the noise level. The amount of attenuation are dependent of the antenna and scanners quality and the amount of interferencies. A FM broadcast notch filter are always a good investment.

/Ubbe

 

[banjo5stringleon]

Are you saying that the PGA103 and the FM broadcast notch should both be used? Or just buy like the PGA103. I found this on Amazon. Would you say this would be a good one? This is what it covers. 5-3500MHz Amazon.com: 5-3500MHz Broadband 20 dB High Gain LNA Low Noise RF Amplifier Module Ham Radio with Shielding Shell for Shortwave FM TV Audio: Home Improvement

Thanks!

 

[banjo5stringleon]

Still a Newbie,
I’ve been searching, listening, and reading about Analog and Digital amplifiers. I found out you have to be careful of how much gain you use. A YouTube clip said if you have too much gain, you could blow out the front end of your scanner. Once again saying something that I heard that I believe I can find the clip for if need be? So I’ve decided to go ahead and work with the coax. Which is something else I’ve learned? Good quality coax is something you should consider, which I believe I have on the base. Slowing down and taking my time and enjoying what I have.

 

[Ubbe]

Would you say this would be a good one?

It doesn't say anything how well it handles large signals. Go to Ebay and search for PGA103+ and you will find lots of amplifiers that are good. They all have the same specification and its only the mechanics that differ, how they are powered and so on. If you got mains power in the attic you can buy the cheapest amplifier that can be powered from an USB cable and a cheap 5volt cellphone charger. You'll need to get adaptors to fit antenna and the coax F connector, or get the more prefered pig tails with the correct type of connectors.

Don't forget the variable 0-20dB attenuator. Get one with F connectors and connect the downstairs coax to that and the other end of the attenuator to the scanner.

FM broadcast filter are optional but never hurts.

YouTube clip said if you have too much gain, you could blow out the front end of your scanner.

I've never heard of that happening. If you transmit nearby, a couple of feet, you can blow out the input of a scanner but not when using an antenna amplifier. Amplifiers cannot produce enough signal level to hurt a scanner, the amplifier will blow first before that could happen.

/Ubbe

 

[banjo5stringleon]

Once again /Ubbe you've been a big help. The gentleman that made the YouTube clip was dated 2013. Technology has come a long ways since then. Thanks for the posted pictures too. EBay made another sell. It's greatly appreciated.

 

[banjo5stringleon]

/UBBE,
One question or two. Where should both of these be placed on the coax. Plus should I have gotten the one for electric. I don’t think the one I ordered said anything about electric?Thanks.

 

[banjo5stringleon]

/UBBE, you did say rereading your last post. That it depends on how they are powered. So just an assumption on my part. Not all amplifiers need to be electric for them to work. Is that a fair statement?

 

[banjo5stringleon]

It doesn't say anything how well it handles large signals. Go to Ebay and search for PGA103+ and you will find lots of amplifiers that are good. They all have the same specification and its only the mechanics that differ, how they are powered and so on. If you got mains power in the attic you can buy the cheapest amplifier that can be powered from an USB cable and a cheap 5volt cellphone charger. You'll need to get adaptors to fit antenna and the coax F connector, or get the more prefered pig tails with the correct type of connectors.

Don't forget the variable 0-20dB attenuator. Get one with F connectors and connect the downstairs coax to that and the other end of the attenuator to the scanner.

FM broadcast filter are optional but never hurts.

I've never heard of that happening. If you transmit nearby, a couple of feet, you can blow out the input of a scanner but not when using an antenna amplifier. Amplifiers cannot produce enough signal level to hurt a scanner, the amplifier will blow first before that could happen.

/Ubbe

Ubbe, I did find an amplifier with the USB power supply. It’s coming from Canada which could be till the end of the month. Thanks again and I’ll read up on where they’re supposed to be placed.

 

[Ubbe]

Where should both of these be placed on the coax.

Amplifiers work the best when installed at the antenna. They will operate as a buffer keeping the impedance constant to the coax and handling the antennas variating impedances without loosing performance. The PGA103+ types can handle a lot of signal without being affected but first try the FM filter between amp and antenna. Then do the dial in of attenuation and check the noise level from a frequency. Then move the FM filter down to the scanner and check that frequency again. Have the filter at the place where it gives the least noise level. At my place that's always at the scanner as filters always give some loss to the signal and the amplifier needs to boost the signal before it reaches any filter. At some locations it might be a huge interfering signal level from FM broadcast that throws the amplifier off and the filter then needs to be installed before the amplifier.

Plus should I have gotten the one for electric. I don’t think the one I ordered said anything about electric?Thanks.

All amplifiers are electric but some need 5volt and others can take anything from 5-24volt. Some have USB connectors and others need wires soldered to them and others needs Bias-T adaptors that feed the voltage to the coax cable.

/Ubbe

 

[banjo5stringleon]

Thank you once again Ubbe

 

[banjo5stringleon]

Amplifiers work the best when installed at the antenna. They will operate as a buffer keeping the impedance constant to the coax and handling the antennas variating impedances without loosing performance. The PGA103+ types can handle a lot of signal without being affected but first try the FM filter between amp and antenna. Then do the dial in of attenuation and check the noise level from a frequency. Then move the FM filter down to the scanner and check that frequency again. Have the filter at the place where it gives the least noise level. At my place that's always at the scanner as filters always give some loss to the signal and the amplifier needs to boost the signal before it reaches any filter. At some locations it might be a huge interfering signal level from FM broadcast that throws the amplifier off and the filter then needs to be installed before the amplifier.All amplifiers are electric but some need 5volt and others can take anything from 5-24volt. Some have USB connectors and others need wires soldered to them and others needs Bias-T adaptors that feed the voltage to the coax cable.

/Ubbe

/Ubbe
My brother-in-law Tim and I cut back the coax today. It made a considerable difference with pulling in the airport’s. I’ve been noticing more traffic then I did prior to cutting back the coax.

As far as the amplifier and FM filter goes. I’m still waiting on the mail. I did get a notice from them both that they are in the mail system. I’m looking forward to trying them on the coax. With the success I noticed from cutting back coax, I’m hoping for a cleaner sound on some of the more noisy signals. And maybe pulling in the weaker signal too. Thanks again.