On Sun, 2008-06-22 at 08:22 -0700, Jim WA9YSD wrote:
> Ahhhhhhhh! I think I found it. Swapped cables on either side of the Bird
> watt meter running between the Hercules II Amp and TT 253 Tuner going to the
> dummy load
> with the Bird watt meter between the amp and tuner and all works well. Put
> it into the antenna and every thing not so well.
> I swapped cables again and guess what the Bird had high SWR. Looks
> like the Jumper from the amp to the Tuner is the problem under that
> type of load. I had to splice 2 cables together to get a 3 footer and
> it works pretty well now. I will have to get a Cable Expert pre-made 3
> footer and I will be back in business.
What you need are TWO Birds. Running them cascaded you will discover
that the input Z of a Bird feeding a matched load isn't necessarily a
matched load. E.g. the Bird changes the impedance seen. To minimize
that, Bird in their manuals and catalog, recommends that a cable be used
with the Bird to make the total added line length any integral multiple
of a half wave in coax. So what you are seeing might not be faulty cable
construction, but rather just a poor length of cable. These impedance
changing effects are greater the more sensitive the slug because the
more sensitive slugs are more tightly coupled to the main transmission
line.
But the connectors could have been attached incorrectly to make opens or
shorts. All fixable, better to fix than to destroy, I think.
>
> What baffles me is why didn't this show up with the dummy load? Worked on CW
> not on SSB, why? Flaky cables!
>
> I use to make up my own
> and they went bad also. I took all my jumper to field day one year tested
> them with a Bird that a fellow ham had and
> got rid of the bad ones and burned them in the camp fire. Made nice
> green colors in the flames. Looks like I will have to do the same with
> this bad one Bringing home the Bird sure
> showed me how things are suppose to work. Never thought I had to ever
> do this again.
>
> Thanks Ken for your help working through this.
>
> Keep The Faith, Jim K9TF/WA9YSD
>
73, Jerry, K0CQ
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