OK, then you nailed it.
It must have been 4mm.
It was a tight fit and very robust.
I once built a linear amp using this technique.
If I were to describe it in detail, you guys would all laugh at me.
We had silly rules in Germany which called for silly circuits.
But, the fact is, it put out 1400w on 80m and I could carry it with just two
fingers of one hand, including power supply!
"Es gibt Dinge, die gibt es nicht." (google translate)
From: email@example.com [mailto:firstname.lastname@example.org]
On Behalf Of Dr. Gerald N. Johnson
Sent: Friday, January 14, 2011 8:52 PM
Subject: Re: [TenTec] ant
In Germany that coil tubing was probably 6 or 8 mm diameter. Practically
1/4 or 5/16" diameter. I just checked a couple banana plugs and jacks. I
get 0.145" as the smallest rigid diameter of the plug and about 0.151"
as the ID of the banana jack which is close to 4mm (0.1575") and
measuring with a dial caliper in that small a hole is subject to error.
I'm sure a vendor of banana jacks like Keystone Electronics will be more
specific about that diameter.
http://en.wikipedia.org/wiki/Banana_connector says the banana plug and
jack is a German invention and IS 4mm diameter.
Checking two handy vintage meters with drill bit shanks. The B&K DVM
jacks take a 0.159, won't take a 0.161. Must be about 0.160 like some
Pomona jacks I found dimensioned on line. My older Simpson 260 series 5
takes 0.157 snugly, not 0.159 in a jack that's rarely been used.
Fortunately the banana plug has a large range of sizes it will fit, part
of its fundamental design if its a true banana. There have been more
solid plugs that are split four ways that aren't as tolerant of jack
73, Jerry, K0CQ
On 1/14/2011 7:08 PM, Rick - NJ0IP / DJ0IP wrote:
> Well guys, Jerry probably touched on the most important factor here.
> The doggone manufacturers somehow assumed we wanted everything smaller and
> smaller and so they compromised performance for size.
> In Germany about 30 years ago a very good OM put forth a scheme for doing
> He is an SK now.
> Arno (DL9AH) suggested making a very large coil out of thick copper
> about 1/4 inch thick.
> It was a monster.
> Ok, this is overkill, but he did it for another reason.
> He then drilled holes (I'll pick a number) "3mm" in diameter into every
> A typical banana plug would fit snugly into these holes.
> Thus you were able to tap anywhere you wanted, just as Jerry suggested,
> using clips.
> These things had about as close to zero loss as you could have.
> Would make a lot of sense using a circuit based on the K1JJ design.
> Measure the correct diameter of the banana plug. My "3mm" was just an
> -----Original Message-----
> From: email@example.com [mailto:firstname.lastname@example.org]
> On Behalf Of Neal Laugman
> Sent: Friday, January 14, 2011 7:44 PM
> To: email@example.com
> Subject: Re: [TenTec] ant
> My bad - I did mean polystyrene, but I was under the impression
> the Airdux coil had a denser plastic.
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