Re: {Collins} 30L-1 Input SWR High on 21/28 bands

I don't have time to read all this now, but so far, so good, and I've
learned a few things. Thanks.

However, I did notice that you refer to RG-8; but Collins specified
RG-58C/U with more loss. Just food for thought. I didn't calculate anything.

73, Mike

On Fri, May 29, 2015 at 4:24 PM, Bill Carns <wcarns@xxxxxxxxxxxxx> wrote:

>  [snip]
> Re the loss of the longer cable helping with stability.  Hmmm..  The loss
> of a typical 9913 type (RG-8U) cable is less than one db total PER 100 FEET
> at 30 MHZ.  The amount of loss injected into the stability picture at the
> input by using a 20.5 foot cable instead of the typical 4 to 6 feet of
> cable is mice nuts – much less than one db.  I suspect strongly if loss was
> the motivation for the recommendation to use the longer cable, the length
> would not have been set at 20.5 feet.
> In fact, Warren Bruene wrote an article about the use of the 20.5 foot
> cable in the 30S-1. ... Gene Senti was the designer of that amp. This amp
> “inherited” the 30S-1 20.5 foot cable recommendation as far as we can tell.
> ... While there is a theoretical basis for using the 20.5 foot cable and
> Don did confirm the theory, he also concluded, as did Art, that it was
> unnecessary and lost in the “noise”.

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