[Amps] Chimney for GS35B

[Roger (K8RI)]

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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