Coax help needed.

[King Mudduck]

Can coax be bad even though i have a low SWR? My antenna has been up now for 3 years and in that time, ive hit stations all over the world on SSB But now, im only getting out around town. Zero contacts and you guys know how well the DX has been of late. Same radio, same coax, same antenna and even with a 300 amp. zero DX contacts.
Help!

 

[The DB]

To answer your question, yes, your coax can be bad and still show a low SWR. In fact, some causes of bad coax will actually make your SWR appear better than it actually is.

How long have you been getting zero contacts?


The DB

 

[King Mudduck]

To answer your question, yes, your coax can be bad and still show a low SWR. In fact, some causes of bad coax will actually make your SWR appear better than it actually is.

How long have you been getting zero contacts? A few months noe. SWR has stayed right at 1.3.




The DB

 

[King Mudduck]

Sorry, im on my tablet. A few months now. My SWR has stayed at 1.3

 

[M0GVZ]

Go to this page...

http://www.qrz.com/

In the middle is a table for Solar/Terrestrial Data

You want to be looking at the figures for SFI, A and K.

When the SFI is going over the 140-150 range then propogation for 10m is good however this also depends on the value of A and K.

If K is higher than 1 then solar conditions start to restrict DX. When they get to 3 then you can begin to wonder whether you've plugged the antenna into the radio. I've experienced K of 4 which just hit almost instantly and I actually swapped radios because the bands died so quickly.

A is an average of K over a period so the higher it is is an indication of poor conditions over the last day or so.

So as I look at that website, K=2, A=15 which suggests that solar activity has stopped play for much of the last day.

 

[King Mudduck]

Go to this page...

http://www.qrz.com/

In the middle is a table for Solar/Terrestrial Data

You want to be looking at the figures for SFI, A and K.

When the SFI is going over the 140-150 range then propogation for 10m is good however this also depends on the value of A and K.

If K is higher than 1 then solar conditions start to restrict DX. When they get to 3 then you can begin to wonder whether you've plugged the antenna into the radio. I've experienced K of 4 which just hit almost instantly and I actually swapped radios because the bands died so quickly.

A is an average of K over a period so the higher it is is an indication of poor conditions over the last day or so.

So as I look at that website, K=2, A=15 which suggests that solar activity has stopped play for much of the last day.

Thanks for this. thing about it. i have a friend, 3 miles away on a RCI 2970N2 with an Imax 25 feet up who is banging the UK and mid west to west coast. Even with more power than him, i cant get a soul. I used to get the UK on a 15 watt radio all the time plus many other contacts in the US but now, nothing!

 

[C2]

one year, I had perfect SWR, but no contacts. I discovered the coax had pulled out of the connector at the antenna and had gotten buried in the dirt over the winter. The coax had gotten soaked, so became a big dummy load.

 

[King Mudduck]

I dont know if this matters but i have great receive just as i always have, no change in that at all. Still hard to understand why. looks like if the coax is bad then my receive would have changed.

 

[C2]

coax can act as an impedance transformer. does not mean it has to be a complete failure for the coax to be bad. receive is small signal in the coax. dielectric will not break down in small signal like it will with big signal on transmit. You should be able to determine signal strength on the local stations, if they are hitting you the same, then mother nature is giving you no love.

 

[Marconi]

I dont know if this matters but i have great receive just as i always have, no change in that at all. Still hard to understand why. looks like if the coax is bad then my receive would have changed.

KM, I once had a Starduster up about 60' feet with an old RG8X coax 100' feet long. It had been used before on an A99 for about 7 years. Over time it had water in the line so bad that it looks to have nearly reached to the radio. I didn't know it, but the line was full of green and black contamination. That antenna out-heard all my buddies in my local area, and the SWR looked perfect from 20 meters and above 10 meters.

I might not have seen or transmitted much signal, but I could hear like an Eagle. I was lucky...it just don't take much signal for our radios to work...even with a very lossy feed line.

Just take you line down and hook it to a dummy load and check it with a meter at both ends...the results, if good, should be pretty close to the same.

 

[M0GVZ]

I might not have seen or transmitted much signal, but I could hear like an Eagle. I was lucky...it just don't take much signal for our radios to work...even with a very lossy feed line.

Beverage antenna, one of the best RX antennas there is and it is low to the ground with a resistor shoved in the earth at one end. Makes an amazing RX antenna but you'd never transmit on it.

 

[King Mudduck]

Well,changed coax,cleaned everything in on and around antenna. Made zero difference! Its a quarter wave dropper ground plane 45 ft up mounted on a 40 ft steel well water pipe, antenna itself is 20 feet above the roof. When it first went up, i tore up the UK but for the last few months, i cant get any one but locals on ssb.