Rich,
R. Measures wrote:
Why a DPDT relay when a SPST relay would do this?.
I should have said what I meant by this too. I was figuring on
paralleling the contacts to increase the current rating. I was thinking
one might do that with a set of 10 amp contacts, making 20 amps, than
use a 30 amp SPST which is as large as your fist. The 10 amp would be a
lot smaller to have to find a place to mount it. A small open frame,
stud mount, would only take up an area of about 1" x 1-1/2" or so. The
switch leg leads could be taken off the terminals and soldered directly
to the coil at one end, and the N.O. contacts at the other. If there's
enough room, the larger framed 30 amp relay would be better.
On Oct 14, 2004, at 6:30 AM, craxd wrote:
Rich,
>>R.Measures wrote:
On Oct 13, 2004, at 10:29 AM, craxd wrote:
Manuel,
I seen some on Ebay for sale the other day. They had several
different band switches and also several roller inductors. To by a
new roller inductor, you might want to try Oren Elliott as I'd say
their pricing would be much less than anything from Henry. The only
frequencies you might run into problems with a roller inductors
would be 50 MHz (6 meters). Roller Inductors have been used in
homebrew and a few factory amps for years. The main thing, say for
15-10 meters, you need to make sure the coil will carry the
current. If it's not large enough, the Q will be affected greatly.
Here though, you could have a large DPDT relay to throw in a 10
meter coil, and use the roller inductor for lower frequencies.
No relay or switch is needed for the added 10m section since, for
10m operation, the roller L is set to zero so the only inductance in
the tank is the stray L in the roller L and the 600 or so nH in the
10m section.
You are right if it's only 10 meters using the coil. What I was
speaking of is if he had a large coil for 10 and 15 meters. The relay
would be used for the tap between them. The roller inductor would be
to zero like you mention. I should have described that plainer, I
don't sometimes =)
Oren Elliott: http://www.orenelliottproducts.com/index.html
Will Matney
Manuel R. Alonso wrote:
Hello,
Does anybody know of a good source for reasonably priced
bandswitches? I called Multi-Tech industries and a decent switch
costs $250.00. The nice one's at surplus sales of nebraska are
also up there in price.
How about uning the Henry Roller inductors in lieu of bandswitch /
tapped coil. The Henry rollers are less than $200.00 ea and that
is a complete assembly.
Does the roller present a problem at the lhigher bands were very
low inductance is needed in the Pi circuit?
The amp will have two 4CX800 russian tubes. tube RL = 975.
Thanks
Manuel R. Alonso
KC4MNE
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Richard L. Measures, AG6K, 805.386.3734. www.somis.org
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Will Matney
Richard L. Measures, AG6K, 805.386.3734. www.somis.org
Will Matney
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