Patch lead

[tesco1]

Hi, i have 25metres of rg213 cable from roof to room, how long can you have a patch lead before loss.

[Oblivian]

1m will give you loss. All cable has a loss. What is fed in 1 end will always be less, but the distance it goes will denote how much loss at the other once added up.

on 2dB loss/m cable. If you put in 6dB one end. It will be degraded to near non readable in 3m

[fungus]

Hi, i have 25metres of rg213 cable from roof to room, how long can you have a patch lead before loss.

I gave you this table on the other thread (General Antenna). From that you can see that your loss at 1090 MHz is going to be roughly 8Db with 25 metres of rg213 (cable only);

http://www.w4rp.com/ref/coax.html

The more you add to that with any lead, the more your losses, including losses for connections (as I think I've seen Oblivian make the point in other posts). That's the reason the experts advise to keep your cable run as short as possible and use cable with as low a loss as you can afford. I use a USB cable with an amplifier from my basestation receiver to the laptop to keep my losses as low as possible. That way the basestation can be installed closer to the antenna and i dont need a patch cable. Some mount their receiver in the roof to keep it closer still. There are many ways to overcome the signal loss issue.

Just keep adding up your losses per metre (it's not hard to get a rough estimate per metre from the table) plus throw in a little for connections.
Regards,
Gregg

[tesco1]

Many thanks everyone, all i wanted to do was use a small pigtail at the receiver end for more flexibility, and generally wanting to know how long this should be, not nice having RG 213 going straight into receiver damage might occur.

[fungus]

Many thanks everyone, all i wanted to do was use a small pigtail at the receiver end for more flexibility, and generally wanting to know how long this should be, not nice having RG 213 going straight into receiver damage might occur.

Make sure that the pigtail patch lead is shielded (for 'noise' as much as anything) and remember it will be longer than a straight lead. I'm not at all sure why RG213 or any antenna cable for that matter cant be attached directly to a receiver unit.
Regards,
Gregg

[tesco1]

Somebody said on the forum somewhere that the bnc connections on hand held scanners are not as robust as base receivers, and the movement of the cable especially RG213 wouldnt be good for it, plus you would be restricted for movement with your scanner with a piece of thick cable coming down from the top. fungus, how do you mean shielded?

[FR24support]

I have many short (18 inch), 6mm diameter "patch leads" here and don't suffer any noticeable loss of data.

I have 10mm Ecoflex from the external antenna and I agree the stiffer coax will add strain to the receiver connection.

[tesco1]

Thanks FR24support, i dont know if you can help me, i want a 9mm bnc solderless male connector and a patch lead bnc male to female. I bought 25 metres of RG213 cable because of the low loss, but the 9mm connectors are more difficult to get than 6mm RG58.

[Oblivian]

You would be better fitting it with N both ends (which will attach to most antenna bulkheads directly) and use N-<whatever> pigtails to cover a wider frequency range.

As for loss, yes there is some, how much depends on the type and quality of seal. And how many you have in-line. Since you are breaking a solid core connection and then surrounding it with air. Search the connector type and 'insertion loss'. For instance a single mill-spec BNC connector.. 0.2 dB min at 3 GHz

And N-types is listed as .15 dB maximum at 10 GHz

[tesco1]

Hi, phoned Nevada and they sorted me out, got a uhf 020 plug for the receiving end of my rg 213 cable, they said i could probably get away without soldering it considering the position it is in, it will not be moving much. They said that it was only necessary to solder at the Antenna end to secure the connection because of exposure to weather, wind movement etc. Also got a Comet HM10 1 metre patch lead, one end to connect to UHF 020, the other has a BNC connection for scanner, waiting for items to arrive in post, fingers crossed no hitches lol.

[fungus]

fungus, how do you mean shielded?

Sorry I missed your question above. An explanation and description of 'shielding' is shown in the link below. Pretty much all antenna cables are shielded by one means or another. Not all patch leads that you can purchase are, or you cant readily see what shielding (if any) it has. Shielding simply helps prevent stray signals (causing 'noise') from being picked up by the antenna cable itself and signal loss. The braided copper shielding shown is not really good for our purposes and the 2nd example shown is better, with double shielding being better still (but more expensive). I'm currently checking out RG6 quad shield to see if it's appropriate for my setup. Dont worry too much about the technical information contained in the article, even as a former electrician I find it difficult to understand.

This section in particular points out the purpose of antenna cable shielding;

"Signal leakage

Signal leakage is the passage of electromagnetic fields through the shield of a cable and occurs in both directions. Ingress is the passage of an outside signal into the cable and can result in noise and disruption of the desired signal. Egress is the passage of signal intended to remain within the cable into the outside world and can result in a weaker signal at the end of the cable and radio frequency interference to nearby devices. Severe leakage usually results from improperly installed connectors or faults in the cable shield."

http://en.wikipedia.org/wiki/Coaxial_cable

The following link gives you an idea of some different types of cable/shielding and the resultant affect on the signal loss.

http://telcoantennas.com.au/site/guide-antenna-cables-connectors

Regards,
Gregg

[tesco1]

Many thanks fungus, i have RG213 cable, maybe more difficult to work with but worthwhile in the long run. I have the connections as in reply 10, just waiting for n-type connector to arrive. I am on the lookout in my area for someone to fit the connector as i do not have a soldering kit.