isotron 200(B) dimensions

Robert,

Sorry, I can't give the information you seek but maybe someone else will come forward. I did want to call your attention to a post by Rich (Link) in another thread. Would building one of these be worth considering?

Neil

(Ironic about the dates of these two posts...)
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Submitted by Rich on September 11, 2006 - 07:57.

...And since the model 200B does need a radio frequency ground system to work, it is legal under Part 15 for AM.

Did you intend to write "does NOT need" a ground?

In any case, here is a paste from the Isotron website about their MW AM antennas:

Antenna should be mounted on a metal mast with a maximum size of 1.5 inches. The mast can be ground-mounted with guy wires, mounted to a wooden pole, or mounted to a tower leg. Antenna should be mounted as high as possible for best performance.

This suggests that some, or even most of its gain could be supplied by radiation from the conductor and/or metal mast leading to a true r-f ground below the surface of the earth.
_______________

..Just a big 'ol LC Tank circuit? It would probably work without the mast pipe!

It's basic concept is that of an LC tank. Except an LC tank isn't an antenna.

Naysayers should try one first before knocking it. But if people want to believe from those who have yet to even try it one time, that's ok too.

Only ones to miss out will be those who do not try.

RFB

Even little oskalatin' tank circuits onna pc board emit them rf's, enough to be sniffed. (Re: Reference/I.F. oscillators)

i want to find someone who HAS one of these and can take measurements and draw up a diagram with those dimensions.

it will give me a starting point to tweak around with.

i am very interested in what this design will do on a AMT5k with the toroid bypassed. i will use a metal mast that spans the length of the two plates but a pvc or wood mast leading to ground. i will ground tx to that metal mast and put the hot to the coil in place of that 50 ohm connector. i will tweak that pvc coil to match the tx output instead of the 50 ohms. maybe a larger tapped coil and large variable cap and will play with setting for peak RF out.

they will not work as is with an amt5k but with some tweaking of the design i believe they will.

This could give you a starting point, at least. These pics are of the 200C, which is the 160m unit. The 200B is a bit smaller and ~10' in length. (Part-15 compliant) No pics of that one, of course..

http://isotronantennas.com/index.php?main_page=page&id=12

200B - 1.650-1.799 mHz.. Pretty narrow bandwidth..

Note the construction. The ground is the lower plate and the r.f. goes through the coil to the top plate. Pretty simple. On the 200C, the tuning rod is connected to the connection between the coil and the top plate adding reactive resistance, I believe.

Here's another place to start from. This guy actually built one!

http://www.pcs-electronics.com/phpBB2/viewtopic.php?t=1092

i saw that. don't like how his design turned out.

a lot of engineering and testing probably went into the isotron 200b to find the best compromise between l and c and the ham versions have been in use and popular for at least 10 years.

the best starting parameters are probably to copy an actual unit.

someone has to own one of these.

160c modified manual
http://isotronantennas.com/download/inst160cmodified.pdf

When you talk about "HAM versions" that has no relevance to "part 15 versions", because HAMS are not constrained with part 15 rules.

The whole mass of whatever you build cannot exceed 3-meters.

Why don't we just give up and wish we had enough will to look for a bridge to jump from.

As for me, the nearest bridge is 7-miles away, and I am too discouraged to walk there.

Just to note that a base driven, 3-meter, linear, vertical whip can be made ~resonant over a very narrow frequency span in the AM broadcast band, using a series loading coil at the feedpoint.

This configuration/condition constitutes a series "LC Tank" circuit, as it is comprised of the L (inductive reactance) of the loading coil, and the C (capacitive reactance) of the 3-meter whip.

Thank you rich.

From your posting I take heart that something can be done afterall by seeking that very narrow frequency span in my band, the AM broadcast band.

Another bridge has been crossed, in the positive way.

I have heard Isotrons on the
HF ham bands, and they work.

I don't completely understand
how they work, but they do.

I have always wanted to buy the
Part 15 version, or try to build
a replica, as I believe others have
done. Didn't RFB build a replica?
My memory is too full of stuff. I
can't remember.

Wouldn't you have to mount the Part 15
transmitter up at the feed point?

Maybe this question was brought up before.

Bruce, SBS 90.9, 88.3

check this out...