[R-390] filters

[Barry]

Speaking of rejection rates, etc., I watched this video last night.  Pretty fascinating stuff (even if it is solid-state).  Interesting to see how some of the first silicon transistors were made, delivered, etc.  The hand work they did for the first ICs was quite involved too.

http://www.pbs.org/wgbh/americanexperience/films/silicon/player/

Regards,
Barry - N4BUQ

----- Original Message -----
> From: "Norman Ryan" <nnryann at yahoo.com>
> To: r-390 at mailman.qth.net
> Sent: Thursday, February 7, 2013 12:01:35 PM
> Subject: Re: [R-390] filters
> 
> Hello, all,
> 
> I imagine the learning curve for making these mechanical filters at
> the factory must have been steep.  Even so, the rejection rate must
> have been considerable, given the delicate construction.
> 
> Sadly, we poor slobs have only one shot at getting the repair right,
> and we're faced with the problem of finding a more durable
> replacement insulation material as well.  Anyone have thoughts on an
> alternative way to close up the filters, say, using two-part epoxy
> such as JB Weld?
> 
> It may turn out that foam pipe insulation as suggested by Graham
> Baxter will work just fine as it normally is exposed to heat from
> hot water pipes and thus ought to last a long time inside a working
> IF deck.  Heat from resoldering the end caps may be too much, thus
> my suggestion of epoxy as a possible workaround.
> 
> One of these days I want to undertake Graham Baxter's repair
> procedure and will share results here.  It likely will be some time
> down the line, though.
> 
> 73,
> Norman