So you're saying Alpha, Ten-Tec, Jim W8ZR, Jerry K8RA and myself are all wrong
and their designs don't or wont work?
73
Jim W7RY
-----Original Message-----
From: xxw0qe@comcast.net
Sent: Mon, 02 Aug 2010 18:54:58 -0600
To: w7ry@inbox.com
Subject: Re: [Amps] New HF amplifier
Jim,
Yes the comments hold true period! Flux in any core with shorted turns will
cause extra loss with the exception of a type -0 core which has u=1. I have
seen shorted turns on a toroid core causing the toroid to heat to the point of
cracking. The shorting contacts on most bandswitches were designed for air core
inductors where leaving the unused part of the coil open can result in
bandswitch arcing. Shorting the unused turns in an air core inductor does cause
some small loss but it is generally deemed to be the preferable choice to
having the bandswitch arc with the turns open.
For what it's worth you can generally make an inductor for 80 or 160m which has
higher Q when wound on a low loss toroid vs air. This statement of course needs
to be qualified with the requirement that we want the amp to be relatively
compact in size so that we can't allocate a spacious cavern for the output
network.
Larry, W0QE
Jim W7RY wrote:
Do your comments hold true for the L coil? The tapped L network coil in most
amplifiers uses a shorting switch. 73 Jim W7RY
-----Original Message----- From: xxw0qe@comcast.net Sent: Mon, 02 Aug 2010
11:05:19 -0600 To: amps@contesting.com Subject: Re: [Amps] New HF amplifier
What are you using as the basis for this blanket comment? There is absolutely
nothing wrong with tapped toroids. What causes problems is treating them as is
usually done for air core coils which have the unused turns shorted out. On a
toroid you do NOT short out any turns if some of the turns are active.
Otherwise you get significant loss and heating in the toroid. Larry, W0QE
Dennis OConnor wrote:
Tapped toroids show that the designer was too cheap to do the job right...
Built cheap, for the cheap! Move along folks, nothing to see here... Move
along... Keep moving... denny / k8do
_______________________________________________ Amps mailing list
Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps
[http://lists.contesting.com/mailman/listinfo/amps]
_______________________________________________ Amps mailing list
Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps
[http://lists.contesting.com/mailman/listinfo/amps]
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|