Larry...
Please look at Jerry's K8RA amplifier schematic again.
The L coil, (which is the coil I am talking about, please see my previous
email) L5 is shown on the schematic does have a shorting switch depicted. In
addition, I ordered (by part number) the exact same custom switch:
S6—RadioSwitch model 86, double-pole 12-
position (30° indexing) with 6-finger wiper
on each deck, p/n R862R1130001,
www.multi-tech-industries.com.
My switch has shorting contacts for the L coil just the same as Jerry's switch.
You're reply?
73
Jim W7RY
> -----Original Message-----
> From: xxw0qe@comcast.net
> Sent: Mon, 02 Aug 2010 19:32:16 -0600
> To: w7ry@inbox.com
> Subject: Re: [Amps] New HF amplifier
>
> Jim,
>
> I did not say that.
>
> 1.) Shorted turns in a toroid core which is active will produce
> considerably more loss than shorted turns in an air core. Whether this
> loss is catastrophic or not and whether you can tolerate it is up to the
> designer. Do you disagree with this?
>
> 2.) Do any of the designs you mentioned have toroids that are tapped and
> on some bands have part of the coil energized and part shorted? If yes,
> point me to a schematic.
>
> 3.) The K8RA designs I see in the ARRL handbook do not have any tapped
> toroids with shorted turns. The 2010 Handbook has individual toroids
> for the input side 160m and 80m coils and on the output has a tapped
> toroid but the turns are not shorted.
>
> 73,
> Larry, W0QE
>
>
>
> Jim W7RY wrote:
>> 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
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