K1JJ Tuner

[ka2pbo]

 Hi All;

 I was thinking of building the K1JJ tuner after I lengthen my 80 meter half wave to 250 ft.I dont know what copper prices were back when Tom first built his but 60 ft. of 3/8 copper tubing at over a buck a foot is nuts . My  question is ; has anyone used #10 or #12 wire instead of the tubing? If so; how did it work? I have some #10 here and the caps so I was thinking of giving it a try.

Thanks

  Rick   KA2PBO

[K1JJ]

Hi Rick,

Tuner inductor  loss is very dependent upon what the impedance happens to be that you are matching on a given frequency. (At the tuner output) Also, the amount of heat will be directly affected by the power level you run.  If you run a standard DX-100 power level, like 100 watts carrier, then don't worry about it.

For example, if you were matching a 15 ohm load and running 1500 watts, you can expect to see some coil heating when using #10 wire for the inductor.  But if the load is 2,000 ohms using 600 ohm OW feedline, like when you match an 80M dipole on 40M, then there should be little heat.

Make it easy to switch between parallel or series tuner feed configurations. This will help a lot too.


Using 3/8" copper tubing lets you match anything at maximum power with little heat loss.

But, take a look at the 1/4" copper tubing prices. This is a good diameter compromise. Also, check the web for scrap metal dealers in your area.  I buy all my aluminum for homebrewing at one and always see a large bin full of copper scrap at $1 /  pound. They usually have sheet, tubing and other copper odds and ends.


Good luck with the project!

T

[flintstone mop]

Even at 2013 money it is not a budget buster. The vacuum variable could; depends on how resourceful you are!!! Tom:::: how many KV would be a minimal cap for this tuner and the PF range???
I am not aware how many built the tuner and did not use a vacuum variable.
I did.
Fred

[K1JJ]

Even at 2013 money it is not a budget buster. The vacuum variable could; depends on how resourceful you are!!! Tom:::: how many KV would be a minimal cap for this tuner and the PF range???
I am not aware how many built the tuner and did not use a vacuum variable.
I did.
Fred

Hola Fred,

Just like the inductor heat example,  voltage rating for the cap depends on the impedance matched and power level used.

Usually, a standard 500 pf  vacuum variable cap rated at 10 KV is more than adequate for any matching job or QRO power level up to 160M.

I have used air variables on several tuners and found 300 pf  at 4KV handled a standard parallel match quite well at 1500w.

Worst case is the air variable cap arcs over and we need a bigger one. So we have little risk trying whatever we have available for the job. WTF.

T

  

[ka2pbo]

Thanks Tom,

 I just found a scrap guy by me. I will take a trip next weekend and go exploring. I just compared the 3/8 and 1/4  copper tubing at Lowes and there is no difference in price....$59.99 for a 60ft coil .Right now I am only running 100 watts(Viking II ) and I will be running 160 meter half wave fed with OWL for all bands. .I dont  have a vacuum variable but probably wont need it for the current power level and antenna match/feedline..I would like to build it with the tubing just in case I build a big rig someday.So we will see what the scrap yard produces but its good to know I can still use  # 10 wire and a few bread slicers for now.

Thanks Again 

Rick

[KB2WIG]

You may consider the length of time a tuna lasts. If you keep her for 10 years, that Cu will be only $6.00 a year......  and you can always scrap it to get some money back.  Why, I've got shoes that are 20 years old and they are still working. I just shine 'em up, and wear them to funerals. And my wife will save money by planting me with them.

klc

[Steve - K4HX]

Find some crapped out refrigerators.

[flintstone mop]

I hope you have success in building this tuner. There was a lot of threads about it and different configurations to accommodate a wide range of antenna characteristics and its use all the way to 10M.
For fast band changes, I like my Dentron 3KA. But the K1JJ tuner is just as effective as a Dentron and $300 cheaper. That coil of copper and a vacuum variable are the only large cost items.
I hang on the vacuum variable as I am using QRO power most of the time.
Fred