Re: How best to inexpensively clean degraded variable caps?
On Mon, Jul 13, 2020 at 07:26 PM, Guy Atkins wrote:
It's tough to beat the excellent "Q" of a top-notch air variable cap!
Amen to that, home town brother!
The reality is that when you spend some serious vacation $$ to show up at an ocean side cliff and/ or exotic overseas ocean beach with FSL antennas and completely depend on the FSL's tuned gain performance to give you DXing success, you had better deploy with with the sharpest variable cap(s) that you can track down. The cost of all-new variable cap upgrades is always less than 10% of the total vacation cost.
Of course I'm aware that most FSL users chase DX with these antennas in the shack, under far less demanding conditions. A variable cap that has minor issues because of oxidation or a less-than-successful cleaning attempt is not going to be a major deal breaker in routine, home town DXing. It's only when you are trying for something bordering on the "impossible" in extremely tough conditions (like chasing African AM-DX at over 8,000 miles at sunset in Hawaii on a 5" FSL) that a degraded variable cap will almost certainly shoot you down. These receptions are barely possible anyway, even with superior propagation and a razor-sharp 5 inch gain antenna.
<<< A simple enough approach to give a modicum of weather resistance to the caps--and forestall weathering-- is to build the FSL components inside of a tote box. I describe that method here: https://swling.com/blog/2017/01/a-new-approach-to-fsl-antenna-construction/ >>>
Guy's approach is good, and would stop any degradation due to salt water air exposure. Even in all the FSL antennas previously deployed to ocean side cliffs and overseas ocean beaches there has always been a waterproof vinyl covering designed to stop rain from throwing off the variable cap tuning, but obviously some oxidation has still been occurring over years of time, throwing off the variable cap performance somewhat. DXers can address this issue any way they prefer, but for the FSL antennas heading for the Rockwork Cliff DXpedition coming up soon, not only will the variable caps be brand new, but the FSL antenna designs will be brand new, developed during the extended tinkering hours of the Pandemic. These combine powerful tuned gain with much lighter weight (and much lower cost) than the 15" and 17" Monster FSL antennas used previously. Shown in the attached design photos, they deliver equivalent performance in a much more user-friendly package. Their construction cost would probably still derail most hobby budgets, but is less than half of the $1K Monster FSL's.
Gary DeBock (in Puyallup, WA, USA)