Coax recommendation
Just keen to get a sense of where the sweet spot is for Coax - I'm needing approx. 20M to run in to the house from the garden....
Currently I use M&P Ultraflex 7, which is great, but also not the cheapest; I get the impression its mainly aimed at the Ham market for transmit, so would this be considered overkill for a receive only LAA+ or ++ if I upgrade?
Thanks,
Mark.
On 23/08/2022 15:18 Mark Scudder via groups.io <mark.scuds@...> wrote:
Good Afternoon all,
Just keen to get a sense of where the sweet spot is for Coax - I'm needing approx. 20M to run in to the house from the garden....
Currently I use M&P Ultraflex 7, which is great, but also not the cheapest; I get the impression its mainly aimed at the Ham market for transmit, so would this be considered overkill for a receive only LAA+ or ++ if I upgrade?
Thanks,
Mark.
Most of the amplifiers are set up for 50 ohm output but it's a simple resistor change during build to give the option of 50, 75 or 100 ohm output impedance.
In actual receiver use the mismatch between 50 and 75 ohm coax is barely noticeable so 75 ohm CCTV cable is a good option.
Our earlier active antennas used CAT5 ethernet cable using one pair as a 100 ohm transmission line, two pairs for DC power with one pair spare. We did manufacture a cross polarised active antenna that used the spare pair as an additional RF transmission line to go with the dual diversity SDR receiver we made some years ago.
The only reason we stopped selling antennas using CAT5 cable was that our professional customers didn't want to replace their existing coax cable runs with CAT5.
What do I use myself? Both at home and in the workshop I use coax cable runs of RG-58u with runs up to 25 m long. It"s mainly due to the ease of installation and the fact we always keep a drum of it in stock to make connecting cables.
By the way in my previous professional life designing and installing coverage enhancer systems for mobile phone networks we only ever used Andrews LDF 4-50 cable. This would be well over the top for HF receive use but it's great for making HF loops!
Regards,
Chris
Regards,
Chris
On Aug 23, 2022, at 1:12 PM, Simon <ohhellnotagain@...> wrote:
No such thing as overkill in rx coax.
If you can live with the 75r ( slight mismatch) coax wf100 is excellent. Buy the proper stuff, ( solid copper inner, copper foil and braid.) 20m wont cost much.. £50 for 100m ..
Ask Chris what he recommends maybe?
Simon g0zen
For HF receive use with the High Z, Loop and Beverage amplifiers the coax losses are relatively low even for long runs so other factors such as cost, lifetime or ease of installation become major factors.
Most of the amplifiers are set up for 50 ohm output but it's a simple resistor change during build to give the option of 50, 75 or 100 ohm output impedance.
In actual receiver use the mismatch between 50 and 75 ohm coax is barely noticeable so 75 ohm CCTV cable is a good option.
Our earlier active antennas used CAT5 ethernet cable using one pair as a 100 ohm transmission line, two pairs for DC power with one pair spare. We did manufacture a cross polarised active antenna that used the spare pair as an additional RF transmission line to go with the dual diversity SDR receiver we made some years ago.
The only reason we stopped selling antennas using CAT5 cable was that our professional customers didn't want to replace their existing coax cable runs with CAT5.
What do I use myself? Both at home and in the workshop I use coax cable runs of RG-58u with runs up to 25 m long. It"s mainly due to the ease of installation and the fact we always keep a drum of it in stock to make connecting cables.
By the way in my previous professional life designing and installing coverage enhancer systems for mobile phone networks we only ever used Andrews LDF 4-50 cable. This would be well over the top for HF receive use but it's great for making HF loops!
Regards,
Chris
Regards,
Chris
Hello, I would like your opinion on this. I to have a question about which coax I should be using.
I have the LAA++ about 4 feet off the ground and I have about 10-11 meters of RG6 quad shield coax running from the LAA++ to the bias-t (which has BNC male to F female adapters on both ends) and then I've got a short 3 foot run of RG-58 (BNC Male) that connects to Ant C on my RSPdx.
The guy at the store told me that if I want to improve my antenna, I should ditch the RG-6 and loose the adapters as they will degrade the signal, but on the other hand, people are telling me that they use RG-6 quad shield coax because of the extra shielding that helps them keep out local RFI. So, I'm confused. Do I keep the RG-6 and adapters or should I find something like RG-213 or RG-8X and put a BNC connector on that? I really don't know what to do as I am getting tons of different answers.
What are you guys using for the coax? My intention was to only use the LAA++ for 0-30 MHz but it totally kicks butt at 87 - 108 MHz, and the air band. In fact it's the best directional antenna I've ever had for FM radio.
There's an old saying "If it's working don't fix it!".
The RG-6 quad shield sounds like it's working really well for you especially at VHF where losses are higher.
The losses with adaptors are minimal at these frequencies so as long as everything is waterproofed keep on using it, enjoy the radio and stop reading coax spec sheets!
Regards,
Chris
I totally agree with Chris.
The only issue I can think of is how weatherproof your F to BNC adapter is. The usual tv-type F connectors are not high-grade.
Getting water into your coax would be desastrous.
As regards 75 ohm (RG-6) to 50 ohm (RG-213), I would not worry about mismatch loss, especially not up to 30 MHz.
Your RG-6 is low-loss and quad shielded which is a great advantage, RG-213 has only a single shield, is much heavier, more expensive and more difficult to handle.
Personally I use a 100 foot length of Hyperflex-5 with the appropriate BNC connectors. It is higly flexible and double shielded.
Admittedly, I do not use my loop antenna at VHF frequencies, only up to 30 MHz. Loss of Hyperflex-5 is slightly higher than RG-213.
Hope this helps,
Regards and good luck!
Gerard
I'm going to get this from Amazon and ditch the F to BNC adapters. As for weatherproofing, I've just covered the connector with lots of electrical tape as I tightly wrapped it around. Hope that will do the job.
Oh, and I do plan to ditch the RG-6Q and replace it with an LMR-400 equivalent for my 25 - 1300 MHz discone since that has an 95' run to the radio. It also does have the UHF connector and I've noticed that UHF reception is poor (the 40cm band for example). Depending on how things go, the discone will be replaced with the Broadband Active Antenna.
D
[Edited Message Follows]
I'm going to get this from Amazon and ditch the F to BNC adapters. As for weatherproofing, I've just covered the connector with lots of electrical tape as I tightly wrapped it around. Hope that will do the job.
Oh, and I do plan to ditch the RG-6Q and replace it with an LMR-400 equivalent for my 25 - 1300 MHz discone since that has an 95' run to the radio. It also does have the UHF connector and I've noticed that UHF reception is poor (the 40cm band for example). Depending on how things go, the discone will be replaced with the Broadband Active Antenna.
I'm going to get this from Amazon and ditch the F to BNC adapters. As for weatherproofing, I've just covered the connector with lots of electrical tape as I tightly wrapped it around. Hope that will do the job.
You need to buy something called “Self-Amalgamating Tape”. This isn’t sticky but it stretched around the joint/connector. As it shrinks it becomes solid. Electrical tape is not waterproof. This stuff is once cured. If I make up F connectors for my TV stuff, I use self-amalg to keep the connector on the cable.
Sent: 10 January 2023 06:47
To: CrossCountryWireless@groups.io
Subject: Re: [CrossCountryWireless] Coax recommendation
"for indoor use only" !!
On Mon, 9 Jan 2023 at 23:24, Rob Q <robman501a@...> wrote:
I'm going to get this from Amazon and ditch the F to BNC adapters. As for weatherproofing, I've just covered the connector with lots of electrical tape as I tightly wrapped it around. Hope that will do the job.
First layer is Scotch 88 vinyl tape. This is slightly stretchy tape that can make a good waterproof layer on it's own for temporary jobs. Do a 50% overlap as you wind it on. Don't use cheap PVC electricians tape it won't last, the adhesive is poor and it will fall off.
Second layer is a layer of self-amalgamating tape. Do a 50% overlap and then knead the tape together so that it seals all the gaps. Self-amalgamating tape on it's own exposed to weather lasts about 18 months in the UK due to UV deterioration. In other countries like Australia it probably falls off in a month.
The third and final layer is Denso Tape. This is a petrolatum tape used for corrosion protection on steel pipes used underwater. Think of it as being like Vaseline on a thick cotton tape and you are pretty close. Again a 50% overlap. Now this stuff is messy and I always had to use my bare hands to work it. It just stuck to any gloves I tried so use your hands but have your hand cleaner ready after. This gives the final protection to the cable and connector and keeps weather and UV off the self-amalgamating layer.
A few years back I had to move a cable I protected like this 30 years before. The outer layer of Denso Tape had a discoloured hard weathered surface crust but as I cut through it the self-amalgamating tape and the Scotch 88 tape it was like the day it was taped up 30 years before.
OK some links:
Scotch 88 Vinyl tape
Denso Tape
I know that Denso Tape is a UK company but I'm sure that there must be local equivalents worldwide.
Regards,
Chris
OK let's do the job properly. This is how I used to waterproof coax cables and connectors professionally back in the day.
First layer is Scotch 88 vinyl tape. This is slightly stretchy tape that can make a good waterproof layer on it's own for temporary jobs. Do a 50% overlap as you wind it on. Don't use cheap PVC electricians tape it won't last, the adhesive is poor and it will fall off.
Second layer is a layer of self-amalgamating tape. Do a 50% overlap and then knead the tape together so that it seals all the gaps. Self-amalgamating tape on it's own exposed to weather lasts about 18 months in the UK due to UV deterioration. In other countries like Australia it probably falls off in a month.
The third and final layer is Denso Tape. This is a petrolatum tape used for corrosion protection on steel pipes used underwater. Think of it as being like Vaseline on a thick cotton tape and you are pretty close. Again a 50% overlap. Now this stuff is messy and I always had to use my bare hands to work it. It just stuck to any gloves I tried so use your hands but have your hand cleaner ready after. This gives the final protection to the cable and connector and keeps weather and UV off the self-amalgamating layer.
A few years back I had to move a cable I protected like this 30 years before. The outer layer of Denso Tape had a discoloured hard weathered surface crust but as I cut through it the self-amalgamating tape and the Scotch 88 tape it was like the day it was taped up 30 years before.
OK some links:
Scotch 88 Vinyl tape
Denso Tape
I know that Denso Tape is a UK company but I'm sure that there must be local equivalents worldwide.
Regards,
Chris