Lucky me!

Still busy with the tower. Arranging the radioshack desk and all the wires and coax cables. I need another lay-out on my desk as I have to add the rotor controller. But first of all everything needs to work before I will do a final install. I finally connected the rotor cable through a 13 pole trailer connector so I can disconnect as soon as there is a thunderstorm approaching. However, nothing worked at all. The nice green light came up and then the pointer stuck. Remember my Kenpro overhaul last year? I changed the scale and forgot to glue it, imagine what happened after a couple of months. The paper absorbs moisture that is always in the air and it will get slightly larger and so it did bulge. Had to correct this first. After the pointer could move freely I thought of how to search for the fault?
Actually it is very simple to measure a 8 wire cable like my rotor cable. Just

connect DC voltage from your PSU to the wires and measure at the other end. So, I connected the + to wire 1 and then moved the - from 2-8. Of course I had to walk all the way to the tower to measure at the other end. Anyway, when I arrived at wire 5 I had no 13,5V, same with wire 6,7 and 8. To make a long story short. It seems the pin-out of the male and female trailer connectors are not the same. That's why I hate those 13-pole connectors I think. After that was corrected the rotor rotates fine.

So, why the title then? I didn't feel that lucky when I was searching for the fault describing above. It did take hours before I finally found the connector problem. Still I feel very lucky.......look what I got for free:

A well known GPS company changed cables at my job a while ago. Since the old cable was going into the garbage bin after it was damaged a little I asked if I could have it. That was no problem. And indeed the sealed TNC connectors were damaged and there were some minor holes in the insulation here and there. It is about 29m (95 ft) long and would fit between my shack and the new tower for covering 90% of the distance. Now, I covered the holes with insulation tape and since the cable was used inside a building I expect no damage or very minor.

The MFJ-259B showed 1 dB loss @50MHz. The online loss calculator tells me 0,9dB loss @50MHz is normal. So, I guess there is nothing wrong with the cable at all.






Time to compare loss at several other amateurradio bands. Measured with the MFJ-259B and compared to the calculator.

MFJ-259B: @50MHz: 1dB, @28MHz: 0,8dB, @21MHz: 0,7dB, @14MHz: 0,6dB, @7MHz: 0,5dB, @3,7MHz:0,4dB, @1,8MHz: 0,2dB

Factory calculator: @50MHz: 0,9dB, 28MHz: 0,7dB, 21MHz: 0,6dB, 14MHz: 0,5dB, @7MHz: 0,3dB, @3,7MHz: 0,2dB, @1,8MHz: 0,1dB

The differences are small. And of course different from each other because the factory is calculating the losses and I measure them with a meter that is not calibrated. However it comes close and it shows this is a very low loss cable which I will use for 6m/UHF and VHF. This cable is not really interesting for HF I think. H2007 might have a little more loss but you hardly notice that, at least I hope so.

Now continue working on the tower and shack before the ES season is over....