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Author Topic: Settings for homebrew amplifier?  (Read 22347 times)
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WA1GFZ
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« Reply #25 on: January 08, 2007, 06:53:39 PM »

You can get away with a nonshorting switch if it has a large enough gap between the contacts.
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WB3JOK
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« Reply #26 on: January 08, 2007, 07:08:37 PM »

But here is an old idea. The switch shorts out the coil as you go higher in frequency, eliminating your concern.

Yes, that is exactly what I was trying to describe but didn't have the picture you posted.

Quote
Note the extra loading cap which automatically comes in at the lowest band.

Now that's a neat trick using a one-pole switch! Wish I'd thought of it myself. Grin
I will implement that once I locate a suitable rotary switch. My loading cap is a vacuum variable (8-1000 pf) and it may take even more than 1000 pf additional...

thanks for the schematic  Cool
-Charles

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WB3JOK
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« Reply #27 on: January 11, 2007, 02:05:22 PM »

What do you think of this switch (from a BC-375, available from Fair Radio cheap)?


Since it's six positions I was thinking of removing every other contact, thus doubling the distance between them...

-Charles

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The Slab Bacon
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« Reply #28 on: January 11, 2007, 02:27:32 PM »

Ah, yes, the ubiquotus BC-375 tapswitch. They are a nice switch. I have one of those for the plate tank bandswitch in my 4x1 transmitter. They prolly have enough spacing right out of the box to work ok. If you dont need them real bad, they still show up at hamfests for a few bux each. Fair (choke, cough, gasp) Radio prolly wants a fortune for them. Although they are by far more reasonable than slurp puss sales of nebraska.
                                                     The Slab Bacon

Oh, Yea that switch makes a really nice clack when you switch it!! 
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"No is not an answer and failure is not an option!"
WB3JOK
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« Reply #29 on: January 11, 2007, 03:38:21 PM »

Fair Radio wants only $3.95 each or 10 for $32. Not bad for a (brand new) ceramic switch IMHO  Wink

On the other hand I will only buy from $urplu$ $ale$ (of Nebra$ka) when all other sources are coming up dry, or on the rare occasion when they are about the same price as other places. They are simply outrageous for some items. The BC-375 switch would probably be $75 there!

I'll buy one or two from Fair and try it out. If there's a zorch problem then I'll remove the contacts.
-Charles
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The Slab Bacon
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« Reply #30 on: January 11, 2007, 04:01:35 PM »

$3.95 is a very good price for a switch like that. At that price it would be hard to say no! they are a neat switch with a very distinctive SNAP when you switch it. i am still finding them in hamfest junkboxes for a buck or 2 apiece. that is the fun of festers. I am always looking for parts. Especially the ones you DONT find at shady o rack Grin Grin

                                                  The Slab Bacon
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WA1GFZ
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« Reply #31 on: January 11, 2007, 04:29:59 PM »

I ran a BC375 switch in a linear with 3.3 KV on the plate worked fine.
I later found a bigger one when I needed a second pole. I did a 2 section plate tuning cap to get minimum C on 10 meters.
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