Tx'ing through a QRM eliminator.

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Buick Mackane
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Tx'ing through a QRM eliminator.

Postby Buick Mackane » 14 Oct 2016, 18:45

Bought a QRM eliminator and it seems to be working ok. It has an internal relay which bypasses the noise circuit on transmit, The relay needs a ground connection during TX, This is usually supplied via the transceivers CAT Socket. Problem is none of my radios has a CAT socket. So the question is how do i get my radio to supply a ground connection to the QRM eliminator when i TX ?
I know nothing about CB Radios, I joined transmission1 thinking i would get advice on how to fix my hillman imps faulty gearbox.

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dt307
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Re: Tx'ing through a QRM eliminator.

Postby dt307 » 14 Oct 2016, 23:50

Pin 3 on the mic of a uniden
Or wire it internally to say the pa jack after isolating it and hey presto that's if you don't want to wack a hole in the rig
Or wire internally and have it coming out the back sandwiched between the case and chassis and add a pigtail 3.5mm socket for a no holes solution
Put a 3.5mm male plug on the qrm box relay wire
And your good to go
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Re: Tx'ing through a QRM eliminator.

Postby Buick Mackane » 22 Oct 2016, 21:38

dt307 wrote:Pin 3 on the mic of a uniden


yeah thats what i was thinking. The PTT normally goes to ground when tx'ing.

Cheers.
I know nothing about CB Radios, I joined transmission1 thinking i would get advice on how to fix my hillman imps faulty gearbox.

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Re: Tx'ing through a QRM eliminator.

Postby Buick Mackane » 25 Oct 2016, 12:03

Using the PTT might not be such a good idea after all. Just checked and the QRM eliminator has 12v on the TX Line. Back to the drawing board.
I know nothing about CB Radios, I joined transmission1 thinking i would get advice on how to fix my hillman imps faulty gearbox.

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Re: Tx'ing through a QRM eliminator.

Postby ghost123uk » 23 Dec 2016, 08:57

Depending on what radio you are using, find a solder pad that goes to the full supply rail voltage (ie 13.8V or whatever your using) when in tx, that's quite easy, and then tap onto that to trigger one of those very small reed relays to in turn trigger the QRM eliminators relay to ground.

EDIT = or find a pad that goes to "x" volts on tx, and as above but pick a suitably rated reed relay. Those reed relays pull bugger all current, so shouldn't stress anything. (or go all fancy with an SCR :o )
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Today's thought = Don't just monitor, key up and talk, otherwise everyone thinks no one else is out there !!!

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Re: Tx'ing through a QRM eliminator.

Postby ChrisMagpie » 23 Dec 2016, 10:25

Zetagi should make one of these specifically for CB, with RF sensing so that it switches off on TX (just like a preamp).
I would buy one, and I'm sure lots of others would, too. Come on Zetagi :clap: save us from the evil that is Power Line "Technology".
Just make sure you can actually screw the PL259s onto the connectors at the back, eh? ;)

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Re: Tx'ing through a QRM eliminator.

Postby Buick Mackane » 23 Dec 2016, 11:37

Thanks for the info ghost i'll look into that. Yeah would be a good idea chris except for the bit about zetagi making them :shock: The MFJ noise canceller has TX auto sensing. But in the manual they advise against using it :wtf:
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Re: Tx'ing through a QRM eliminator.

Postby ChrisMagpie » 27 Dec 2016, 05:08

PLL02A wrote:Thanks for the info ghost i'll look into that. Yeah would be a good idea chris except for the bit about zetagi making them :shock: The MFJ noise canceller has TX auto sensing. But in the manual they advise against using it :wtf:

:D Zetagi have got the edge on Made From Junk then, as Zetagi have got the TX auto sensing working fine in their existing preamps ;) I'm not sure about the unfused power leads and the lack of rubber grommets, where power leads pass through metal cases, but details details . . . :lolno:
The Zetagi HP28 could be evolved into a QRM eliminator. The most expensive development cost would probably be making a new front panel for the existing metal case.
I will be expecting Zetagi to send me a review sample in due course :) :D :thumbup:

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Re: Tx'ing through a QRM eliminator.

Postby dt307 » 28 Dec 2016, 03:59

as been said use a relay to sort it inside the qrm box and then wire it as i said
or you could isolate the ptt wire with a diode and do it that way.

if you need me to draw up anything to add a relay ect let me know m8
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Re: Tx'ing through a QRM eliminator.

Postby Buick Mackane » 06 Jan 2017, 14:52

Just treated myself to a yaesu FT-817. So its just a matter of plugging the QRM eliminator into the yaesu's CAT port. I found this diagram online. Far as i can tell all i have to do is connect the relay's negative wire to the CAT ports TX ground pin then run a ground wire from the CAT ground terminal to ground. Is this correct ? No other additional components needed ? And what type of plug do i need to fit the CAT socket ?


Imagewindows screenshot
I know nothing about CB Radios, I joined transmission1 thinking i would get advice on how to fix my hillman imps faulty gearbox.

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Re: Tx'ing through a QRM eliminator.

Postby dt307 » 06 Jan 2017, 15:34

should be fine i would put a small 500ma fuse in series inside the x phase for protection

nice for the extra effort on drawing the detail the the pl plugs
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Re: Tx'ing through a QRM eliminator.

Postby dt307 » 06 Jan 2017, 15:37

forget what i said i just checked the diagram of the x phase its got dc blocking built in on that line so alls good
163dt307-chris




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Re: Tx'ing through a QRM eliminator.

Postby Buick Mackane » 06 Jan 2017, 15:39

dt307 wrote:should be fine i would put a small 500ma fuse in series inside the x phase for protection

nice for the extra effort on drawing the detail the the pl plugs


Cheers chris. Never thought of adding a fuse

Do you know what type of plug i need for the CAT socket ?
I know nothing about CB Radios, I joined transmission1 thinking i would get advice on how to fix my hillman imps faulty gearbox.

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Re: Tx'ing through a QRM eliminator.

Postby dt307 » 06 Jan 2017, 16:27

cant quote me on this
8pin mini din male plug im sure i used an old keyboard ps2 type on a yaesu years ago

dl the manual it will say for sure in there m8
163dt307-chris




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Re: Tx'ing through a QRM eliminator.

Postby Buick Mackane » 06 Jan 2017, 16:31

dt307 wrote:cant quote me on this
8pin mini din male plug im sure i used an old keyboard ps2 type on a yaesu years ago

dl the manual it will say for sure in there m8



Ok chris i'll take a look at the manual, Cheers. EDIT the diagram above says 8 pin mini din, But its kinda blurred, Never noticed it :)
I know nothing about CB Radios, I joined transmission1 thinking i would get advice on how to fix my hillman imps faulty gearbox.


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