Tomm, John and the group,
I agree about not using nylon in high RF fields. Best to use something
better. Going directly to John's question about 3/8"x1/2 inch
insulators, instead of going to the hardware store and buying nylon,
place an order with MSC for virgin teflon rod. You can drill and tap it
for any sized screw you need. A 12" length that is 3/8" in diameter
lists for $3.59. That looks like 3.59/22= $0.16 each! Not bad for an
insulator that you don't have to worry about (I allowed an inch for
waste in saw cuts). They also carry fiberglass rods, tubes and sheets,
micarta, silicon rubber and many other useful items.
Look here: <http://www1.mscdirect.com/CGI/NNPDFF?PMPAGE=1790>
Their home page is <http://mscdirect.com>
MSC is a good outfit to deal with. They have a GREAT on line catalog
and can deliver almost anything you can imagine in the way of hardware,
materials and tools. I use them all the time and highly recommend them.
73, Tony W4ZT
Tomm Aldridge wrote:
>John,
>
>In my opinion, the use of Nylon for general standoffs in an RF amplifier
>is perfectly fine if a bit of thought is given as to the temperatuer
>they will be exposed to. I would not consider Nylon for a tank or plate
>coil former nor for the building of capacitors (as a dielectric). I use
>a machined Nylon couple between my two roller inductors in my balanced
>tuner and have seen no issues there. Supporting your plate coil on
>Nylon would not be advised due to both RF fields and high temperature.
>Instead of ceramic standoffs consider G-10 glass reinforced epoxy stock.
> You can get it from McMaster Carr in a variety of shapes, including
>tubes suitable for coil winding.
>
>Tomm, KD7QAE
>going down in frequency since 1975...10GHz >>> 1.8MHz
>
>John Irwin wrote:
>
>
>>I made the original inquiry about the nylon I found at the ace hardware store
>>. These little cylinders are the same size,shape as ceramic standoff
>>insulators commonly used in amplifiers. I was looking for a low cost
>>replacement for ceramic standoff insulators made expensive by the "PARTS
>>MERCENARIES" that seem to have infected our hobby today.
>>It is likely I will fork over to get ceramic as I don't want to take chances,
>>with nylon melting ,softening. or crystallizing. What with big
>>bangs,kapow,parasitics, spark gaps and other problems. I will play it safe.
>>Nylon goes back to ace. what about glass?
>>
>>Nylon cylinders cost a quarter. ceramic, well a lot more.
>>
>>anyone know of a low cost source for ceramic standoff insulators,3/8"
>>diameter,length 1/2" or something similar.
>>
>>john kb9tc
>>
>>
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