- Posts
Why can’t we send the AM TX signal to an antenna via the usual RG 58 cable, like other small systems do? IOW, I would rather keep my TX warm and dry inside, while sending only its signal to an outside antenna.
There must be some sort of legal or physical restriction, else everyone would be doing this. What, exactly, is it?
TIA …
Total posts : 45366According to Section 15.219(b) of the Rules, the total length of the antenna, transmission line, and the ground lead cannot exceed 3 meters. To maximize the allowed antenna length, the transmission line length is usually made zero.
Total posts : 45366Ken,
Ermi is correct and note that the cable you referred to is the transmission line. These too, though shielded, will radiate a signal in most circumstances, thus the FCC limit. What they are trying to do under 15.219 is limit the radiation by any and all conductors. Some might view the audio and power feed lines as “transmission lines”.
Neil
Total posts : 45366given the way the fcc has been ruling as of late with regard to the 3m rule, i think we may be better off using talking house type transmitters.
there is very little room for interpreting compliance when using a talking house.
i would like to see some feedback on talking house installs.
how was it setup, how much range, any fcc visits and the outcome of any fcc visits.
seems the users getting popped for excessive ground lead have been using rangemasters.
[comment directed referencing a particular person and which was speculative was deleted by a moderator]
also lets expand this to chez radio installs. same questions as above.
Total posts : 45366Robert,
“i would like to see some feedback on talking house installs.”
I have a Talking House and I can’t get it to work without extreme hum. I think it may be the PS, but not positive. Also, music reproduction is poor … voices are listenable, but not up to my standards.
I understand there are different versions, but I don’t know how to tell one from another. I also understand they may have used circuit components from different sources, which throws yet another variable into the mix … seems one batch TH tx’ can have different performance and behaviors than another.
So, it’s just sitting at the moment … I’ll try to get back to experiment with it when I am actually on the air with a more trouble-free system. I’m thinking I may try it with battery power.
It has an actual antenna cable feed on the rear. How would that be an advantage, considering Section 15.219 rules? Also, it’s a 75-ohm impedance TV cable connector, not a 50-ohm radio antenna connector.
Total posts : 45366[quote] Also, it’s a 75-ohm impedance TV cable connector, not a 50-ohm radio antenna connector. [/quote]
this is for the optional and supposedly certified external ATU/Antenna combo.
Total posts : 45366One of my T.H. xmtrs was doing the same thing. In my case the cure was adding a 8/500/1000 ohm audio transforner between the source and the audio input of the T.H.
I connected all three pairs to RCA jacks and tried different combinations until I liked it. I had the output from a weather radio earphone jack going into the 8 Ohm pair and the 500 Ohm pair connected to the T.H.
The transformer also works as an isolator, so the hum went away and the higher impedance input helped the fidelity.
Total posts : 45366this is for the optional and supposedly certified external ATU/Antenna combo.
If standard html quote tags like the above don’t work, why not? This forum seems to have some oddball methods of quoting. How are we supposed to quote portions of previous posts?
Anyway … Yes I understand, but (here we go again) that is for TV reception, not transmitters.
Sometimes I get really frustrated going through a tray of adapters just to get from my ordinary but professional studio gear to some piece of consumer grade gizmosity.
(rant ends) 😉
Total posts : 45366If standard html quote tags like the above don’t work, why not? This forum seems to have some oddball methods of quoting. How are we supposed to quote portions of previous posts?
Square bracket tags like [quote] and [b] and [i] are from the old “BB code” days from forum space. The current ver of our CMS doesn’t recognize BB codes anymore.
The “Input format” link at the bottom of the compose bucket includes this url:
describes the tags to use here, which, for most users would be:
<em> the tag to open and close italics</em> – often used to replace [quote] [/quote]
and
<strong> the tag for bold</strong> – often used for emphasis.
The “Input format” drop down immediately below the compose bucket has the full info.
Total posts : 45366Y’all have me convinced 😉 ASAP, I will try to set up with battery and digital wireless gear to get power and audio content … right at the bottom of the TX/antenna system.
But that still leaves proper grounding. I don’t have schematics for either of my current TX units. Is RF antenna ground isolated from power and audio grounds?
Total posts : 45366Filters – BTDT. Couldn’t find a way to quote text.
How about a button to quote selected sections … which would also automatically create a light background color for the quoted text when it appears in the message? That would make it obvious which part of a message is being addressed.
Just a suggestion.
Total posts : 45366Don’t have one lying around, I’m afraid. Can you give a brand and part number?
I do have a ground loop audio isolation xfrmr, Radio Shack no. 270-054. But I tried it and it had no effect.
- You must be logged in to reply to this topic.
