Gerald already mentioned using Teflon sheet. I'd use high temp epoxy or
glue instead of screws. I don't like electrical conductors sticking
through insulating material.
Whether you use Teflon or Silicone rubber, be sure to overlap the ends
by a good half inch to an inch. Beyond an inch is just wasting material
I like Alpha's use of Silicone rubber sheet. I find it easier to work
with and it'll handle the high temps. I use the red, high temp Silicone
RTV to fasten them to form the chimneys. I picked mine up from the
manufacturer, but that's no longer an option. The only drawback is you
need to keep them clamped for 12 hours or so, while the epoxy can be
purchased in quick setting versions that will handle the heat. I have
used paper clips to hold the ends together. Spring loaded clamps used in
wood working also work. They can also be sewn with a hefty needle. Just
make sure to allow for pulling the thread out. You may not find the
quick set, high temp Silastic RTV, or epoxy at the local hardware
store. If you keep the tubes in an air tight container they will last
far beyond the expiration date on the tube with an EXCEPTION. The non
acetic type will separate out and although the stuff will last well
beyond the expiration date, it's nothing like the regular stuff. I have
tubes of the stuff that smells like acetic acid that have been opened
that are still good close to 20 years past their expiration date. The
same approach works with liquid electrical tape which under normal
conditions does not last long once the can has been opened. A pint or
half pint, seal-able jar works well for the liquid tape. I use a
relatively small Tupperware box for the Silastic RTV tubes.
I don't know if this approach would would work with the non Silicone RTVs.
Alternative for forming chimneys. Get a wood, or plastic form. Pipe,
wood, what ever of the proper size to wrap the Teflon, or Silicone
rubber sheet around. Use hose clamps, large tywraps, or plain old
electrical tape to hold the Teflon, or Silicone rubber until the glue or
RTV sets. If you use tape, leave at least an inch between successive
wraps. The RTV will cure much faster.
Dow Corning is no longer Dow Corning. They are now just a part of Dow
Chemical. Corning is no longer part owner. The Dow Corning logo is gone
from in front of the plant. I don't know for sure, but I think the
change is complete except for eliminating redundancy. I don't know for
sure, but I don't think Dow has a company store any more. I used to get
4' X 8' X 1" sheets of Styrofoam for just over $3.00 from Dow. Dow
Corning closed their company store (for employees), probably 10 or 15
years ago.
73,
Roger (K8RI)
On 10/27/2016 Thursday 9:10 AM, Mike wrote:
Hello,
Need a couple of teflon chimneys for a pair of GS35B amps. Suggestions on
where I can get them?
Presently using PVC, but have had not good results in the long run with
these type of chimneys especially since I do a lot of RTTY contesting.
73,
Mike, K4GMH
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