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Post by jimhenry2000 on Jan 21, 2017 3:43:08 GMT
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Post by Deleted on Jan 21, 2017 17:21:06 GMT
Experience With Isotron Antenna is Lacking
Over the years I don't recall much said about Isotron antennas, except the occasional curiosity like Jim Henry has at this time.
Although possibly a few years ago a member named "RFB" might have posted some positive remarks about it based on his engineering experience.... this would be at part15_us.
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Post by Deleted on Jan 21, 2017 17:41:19 GMT
I think that Part 15 Engineer over at Part15.us recently recounted his experiences with an Isotron Antenna. He purchased a Talking Sign from me to test the thing, and was disappointed with the performance (not much better than the wire antenna the transmitter came with).
Others have expressed the theoretical view that a monopole antenna with ground is at least as good as the Isotron. I keep an open mind about these things, as I've found that often, experience can contradict theory. However, the burden of proof then needs to be higher. And I've seen no such evidence that the Isotron performance meets the hyperbole.
Station8, an ALPB member, is currently developing a new AM antenna and he states that his testing results are very promising. He apparently is planning on releasing more information about it in the near future. I think that I would wait and see what he has come up with, as the Isotron is very expensive, and in the meantime go with the tried and true monopole.
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Post by Deleted on Jan 21, 2017 18:47:34 GMT
Measured Words
DavidC referred to the experience of Part 15 Engineer: "...the performance (was) not much better than the wire antenna the transmitter came with)."
Not much better also says that the Isotron is somewhat better than the included wire antenna.
But considering what else DavidC said, the Isotron has not yet been compared with a vertical outdoor antenna with radial grounds, therefore THAT is what needs to be done if we want a final answer.
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Post by End80 on Jan 21, 2017 19:42:46 GMT
Maybe, but often "not much better" means it made no difference at all.
But if you compared the Isotron to a vertical with ground radials, wouldn't you have also employ radials for the Isotron as well? -To determine a a fair comparison? (I assume the Isotron benefits from a good ground system as well. But, perhaps I shouldn't be even commenting since I don't know what an Isotron antenna actually is!, but it does seems to stand to reason)
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Post by jimhenry2000 on Jan 21, 2017 20:37:03 GMT
The ISOTRON claims to not need a grounding system but I cannot imagine that it would not perform better with a ground. Also, from what I have read I don't think the TH would be an appropriate transmitter to test it with due to the TH's internal antenna tuner designed for the TH's stock antenna. Maybe, but often "not much better" means it made no difference at all. But if you compared the Isotron to a vertical with ground radials, wouldn't you have also employ radials for the Isotron as well? -To determine a a fair comparison? (I assume the Isotron benefits from a good ground system as well. But, perhaps I shouldn't be even commenting since I don't know what an Isotron antenna actually is!, but it does seems to stand to reason) |
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Post by Deleted on Jan 21, 2017 20:52:23 GMT
Antennas With No Ground Connection
Yes, I recall reading that Isotrons do not need to be grounded, and the same is true of balanced dipole antennas, but I have always wondered...
In such cases what happens when a transmitter is grounded to the earth? Does it reduce the efficiency of the Isotron or dipole? Does it improve performance? Or, the other possibility would be that it does nothing.
In all the writings and discussions of these antennas over the years I've never seen that simple question addressed.
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Post by Deleted on Jan 21, 2017 22:03:14 GMT
jimhenry2000, both the Talking House & Talking Sign have 50 ohm antenna jacks that bypass their internal tuners, so they are actually ideal for testing antennas - commonly available (the Talking House at least), relatively inexpensive and easy to set up and use.
I don't recall the exact comparison between antennas that Part 15 Engineer reported, but I do know that he was not overly impressed, given the price of the Isotron.
My impression is that the Isotron is mostly marketing hyperbole and wishful thinking. There are limits to how well antennas can perform, and if you claim otherwise, you have to be able to prove it on a repeatable basis. Some report success with the Isotron, but a lot don't. I suspect that those reporting success would have just as much or more success with a grounded monopole, as other factors are coming into play (such as soil conductivity, etc.).
I've experienced huge variabilities with Part 15 AM using the same transmitter & antenna setup but in different locations. I've gotten ranges of anywhere between 1/8 mile to well over a mile. The latter was achieved in an installation on a river flood plain in a flat but suburban location. The Isotron might have performed well there too, but not because of its alleged intrinsic properties. Interestingly, I had the least success on Bowen Island, pretty much rural (so little noise), but basically a rock sticking out of the water (so very poor soil conductivity). That at least suggests that the effectiveness of your ground probably has more of an affect on your signal than ambient noise.
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Post by End80 on Jan 21, 2017 22:39:42 GMT
TheISOTRON claims to not need a grounding system but I cannot imagine that it would not perform better with a ground. Also, from what I have read I don't think the TH would be an appropriate transmitter to test it with due to the TH's internal antenna tuner designed for the TH's stock antenna.
You just reminded me of something, You might want to consider an outdoor install, even if it had to be put on the side of the house (just above the ground), by putting it the same type encloser as TH company sells their outdoor units in: sales.talkinghouse.com/shop/item.aspx?itemid=46
In a previous discussion about their outdoor unit at www.part15.us/forum/part15-forums/outdoor-mounting-talking-house Jim Dee offered some informed speculation on what kind of weatherproof boxes they use for their outdoor talking house units:
Those enclosures appear to be either telecommunication or cable interface junction boxes. At least this is the conclusion that I have arrived at after seeing the few pictures available on the internet.
What few pictures I have found of the outdoor enclosure show only the front of it, opened up, with the talking house mounted inside of it, whip mounted on the top.....and those pictures aren't really detailed or reveling.
So the best I can tell from looking at the little reference pictures that I can find, those enclosures are more likely designed for location based telecommunications networks, or maybe even for complex building CATV connection taps.
Come to think of it... Those enclosures may be in use as junction boxes within very large LAN systems.
Finding a source for this type of enclosure may not be any more difficult than taking measurements of the talking house and talking with a communications installer (phone / cable / net). |
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Post by End80 on Jan 21, 2017 22:59:46 GMT
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Post by jimhenry2000 on Jan 21, 2017 23:35:54 GMT
Well I will definitely be doing an outdoor install after initial setup and configuration, once I receive my AMT-5000. Got an email this morning that I should have it in a few days. My second floor electronics shop will also become my studio and that opens to an outdoor deck. At ground level my home is 150' above the street. I have a 10' mast out there on the deck that holds my Vantive Pro 2 weather station but I also have a 20' telescoping metal mast available plus a 25' telescoping fiberglass mast that I used to use for my AM/SW reception antenna. The latter (fiberglass) is not suitable if I put up an ISOTRON due to the nature of the antenna. I do have a few weather proof outdoor enclosures around from my days dabbling as a WISP so I could use one of them but I might buy something newer and lighter like the one you illustrate for the TH. Also glad to hear that one can bypass the internal tuner of the TH. Re the ISOTRON, I actually do have one. I have read good reviews of the ones cut for various amateur bands but I'm not taking anything for granted. I am trying to be deliberative in how I proceed and want to be familiar with the xmtr and it's performance with a more conventional antenna well before I get to the ISOTRON. Whatever antenna I use I am concerned about grounding as my property is very rocky with a thin layer of topsoil. That will be a challenge. The ISOTRON claims to not need a grounding system but I cannot imagine that it would not perform better with a ground. Also, from what I have read I don't think the TH would be an appropriate transmitter to test it with due to the TH's internal antenna tuner designed for the TH's stock antenna.
You just reminded me of something, You might want to consider an outdoor install, even if it had to be put on the side of the house (just above the ground), by putting it the same type encloser as TH company sells their outdoor units in: sales.talkinghouse.com/shop/item.aspx?itemid=46
In a previous discussion about their outdoor unit at www.part15.us/forum/part15-forums/outdoor-mounting-talking-house Jim Dee offered some informed speculation on what kind of weatherproof boxes they use for their outdoor talking house units:
Those enclosures appear to be either telecommunication or cable interface junction boxes. At least this is the conclusion that I have arrived at after seeing the few pictures available on the internet.
What few pictures I have found of the outdoor enclosure show only the front of it, opened up, with the talking house mounted inside of it, whip mounted on the top.....and those pictures aren't really detailed or reveling.
So the best I can tell from looking at the little reference pictures that I can find, those enclosures are more likely designed for location based telecommunications networks, or maybe even for complex building CATV connection taps.
Come to think of it... Those enclosures may be in use as junction boxes within very large LAN systems.
Finding a source for this type of enclosure may not be any more difficult than taking measurements of the talking house and talking with a communications installer (phone / cable / net). |
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Post by End80 on Jan 22, 2017 0:53:09 GMT
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Post by jimhenry2000 on Jan 22, 2017 5:06:21 GMT
Thank you I will check it out. |
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Post by Druid Hills Radio on Jan 23, 2017 15:21:02 GMT
Thank you I will check it out. Some YouTube videos: |
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Post by End80 on Jan 24, 2017 1:56:31 GMT
Jim, I don't know if it's already been mentioned or if you seen it before, but this link specifically addresses an outdoor install of a SStran and an assembled antenna www.radiobrandy.com/PART15AMANTENNA.html
He offers for sale pre-built antennas as the one shown, but this page is many years old and I don't know if he even does that any more, but the page is still worthy of a look over since it is exactly what you want to do. 
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