As a member of the G3PYE contest minions, I bought two 25m runs of Ecoflex-15 back in 2011. A year later we started to notice less power at the antenna end of the runs, we initially put this down to a poor cable batch or damage from use/storage and after some basic analysis we just decided to buy another two 25m runs thinking nothing more of it. But after a year of rolling them out every Tuesday and coiling them again we started to notice the same power dropping issue happening again! Due to the first runs failing we were more softly softly with the 2nd set of runs, keeping the coiling diameter around 1.2m, ensuring no tight bends or anything leaning on the coax during transporting but still both runs clearly deteriorated. This was getting expensive so this time we wanted to know what was going on.
Ecoflex-15 comes in many guises, we had a run with the fireproof outer and some runs with the normal PVC outer, this means the runs must have been from different batches/drums. None of the runs were the ‘Plus’ version which has copper coated aluminium strands as the inner conductor, had it been the ‘Plus’ version we might have concluded the copper was detaching from the aluminium. However after talking to many people and some suppliers about the issue we concluded it was down to repeated coiling and uncoiling which has fractured the foil braid in numerous places leading to an increase of the loss along the length.
John G4BAO analysed one of the 25m runs of our Ecoflex-15 and provided this comment;
“The spec suggests a loss of 0.6 dB @50MHz , 0.75@144MHz, 1.9@432 and 3@1296.
My HP VNA measures 1.0 dB@50MHz , 2@144MHz, 4@432 and 9 dB@1296..
Clearly something is wrong!
I’ve carefully re terminated it and there are no obvious dents or damage. The DC loop resistance measures spot on and the Capacitance /m measures 70pf against a spec of 77pF/m. The return loss is typically >25 dB up to about 400MHz and worst at 15 dB at 1296MHz”.
We raised this issue on the UK VHF Contest Yahoo reflector for peoples ideas of they thought might be wrong, we concluded it was the repeated coiling and uncoiling which had caused numerous micro fractures in the foil shielding along the full length of the run, each fracture adding a small amount of attenuation which cumulatively resulted in a 3 times increase in attenuation at 1296MHz. Although our issue was with Ecoflex-15 the datasheets for both Ecoflex-15 and Ecoflex-10 state a similar construction of foil shielding.
In fairness a few operators who are using Ecoflex-15 in fixed installations, including on loops around rotators, and who were able to measure the loss in-situ, found no apparent degradation in their runs.
As such, at G3PYE, we changed coax types and purchased two 25m runs of LBC-400 to try as an alternative. We bought it from http://www.gigatronix.co.uk/ who supplied the coax terminated with crimped and heatshrunk N-Types ready to go, other options are available. A single 25m run of LBC-400, terminated in N-Types, was £41.03 http://goo.gl/wnXIaR, delivery adds a bit coming to £62.44, this vs Ecoflex-15 which for a similar 25m run is £147.25 for the coax, an additional £18 for connectors then delivery on top, I’d say LBC-400 is a bargain being ~£124 cheaper.
The Ecoflex-15 datasheet shows it has less attenuation vs LBC-400, but as we found those claimed figures don’t last for long! Claimed Loss figures for 100m runs of each coax type for the popular VHF and UHF bands are;
Another point to make is, LBC-400 is much much lighter (exactly half the weight) so it is much easier to handle and has less loading on the mast.
We mainly use masthead systems (70cm & 23cm) so coax loss from the radio to the masthead box at the top of the mast is not a real concern, but that’s not true for all bands or use. So far we have not seen any issues with our runs of LBC-400, I guess that was because we come from really poor Ecoflex-15! However the way we think about it; LBC-400 is 1/3rd the cost of Ecoflex-15 so we can renew it 3 times over vs 1 run of Ecoflex-15.
Food for thought…