A shocking discovery!

 

I borrowed a Spectrum Analyzer from work to measure my IFL losses at HF.  I always figured the 500' runs of LDF4 to the top of the hill should only have a db or two of loss at the HF frequencies.  This hypothesis is a result of  the cable specs however in real life problems occur making the losses more then expected.

The NANO VNA made an excellent source.   Set it up to test from 0 MHz to 52 MHz and was presently surprised that this little guy spits out RF  when idle.  Below is the NANO direct to the Spec An though 18" of RG59.   

  

There are 2 1X4 switches located at the beginning of the forest about 100 ft from the ham shack.   The original one has all the IFLs going up the hill (100' to the switch and  400 ' of IFL to the top)  and I refer to it as the "hill" switch .   The other one is just behind the house ( 50' to the switch )   and the antennas are all located close by.   

The first test I did was the IFL to the "house switch "  and I was quite shocked.   I removed the IFL IP to the SW and connected it to the spec an and found the following ...

12db of loss ...HOLLY SMOKES SHOCKING.   I had just replaced this cable 2 years ago!    The IFL was in 3 chunks.  I automatically assumed that it would be the outdoor chuck ,  30' of some sort of hardline.   I almost untapped the outdoor joint but opted to test the first leg that joined just inside the house.   Again I was shocked because it was inside where the loss was.     The culprit tuned out to be a 18" chunks of IFL that ran from my 3X1 switch to my 4X1 switch a piece of RG58 that had to be 10+ years old or maybe more.   This cable had been in place since I installed the switch a decade ago.  

Unfortunately I didn't take a picture or test all the way to the switch but I did test to the end of the first chunk of IFL and had next to no loss.   I have some further testing to do and will test to the switch the next time I am at it.  

Next up was the IFL from the house to the hill switch.  

Nanao OP via 18" cable ...

IP to the hill switch ...

Below 26MHz there was less then 1 db of loss ,  above 26MHz about 1 db of loss ... please with this !

I have a direct500'  run of LDF 4 from my 3X1 switch in the shack to a 60m dipole at the top of the hill.  This is the one that I was most interested in testing!   

Again ,  op of  nano direct to spec an through 18" cable 

500' at the other end of the IFL

Below 26 MHz only 1 db of loss ...YIPPIE ,  better then expected.   And only 3 db loss at 52 MHz!

I still have a  few  of outstanding tests to do .....

1 - IFL to house switch

2- IFL to the 15/10/6 fan dipole at the top of the hill. 

3- 2 chunks of RG 6 that terminate just outside the house at the " satellite" pole

4- I am suspicious of the IFL to the 160m inverted L at the top of the hill.  Its a direct run of IFL to the switch.  I need to reterminate and throw some connectors on it ( Not happening this fall ) 

5- Test to the " House" 15/10/6 fan connected to the " Hill" switch.   It does not seem to perform as well as I would expect.   

6- Some random chunks of IFL that I have in storage to establish that they are good and what attenuation I can expect.