QRM Eliminator (Why you need to connect a PTT cable)

[@volosguard]

Thanks for this great video! I own Yaesu FT-710 and I wonder where should i connect the PTT cable (the one with RCA connector on the one side and naked on the other). I suppose on the Tuner/Linear 8 pin connection soldering TX GRD and GRD pin to a 8 pin mini din connector, but not sure....

[@n4hnhradio]

If you don’t use an amplifier or an antenna tuner, the 8-pin Tuner/Linear connector can be used. You need ground and PTT. I use a Heil FS-2 footswitch, so I don’t have to tie up the Tuner/Linear connector.

[@hamidch632]

i have a yaesu ft80c ,and atu 100 tuner , can you help me out in the setup with this qrm eliminator ? how to set it up, how to connect tuner with the rig and the qrm elimnator

[@n4hnhradio]

The QRM Eliminator can be installed between the ATU and the radio, assuming you don’t use a linear amplifier. Connect a coax from the radio to the QRM Eliminator transmitter connection. Connect a coax between the main coax connection of the QRM Eliminator and the transmitter connection on the ATU. Connect your transmit antenna to the ATU. Connect a noise receive antenna to the auxiliary coax connection on the QRM Eliminator. Connect an RCA cable between the QRM Eliminator PTT connection and your transceiver’s TX GND (PTT) connection. It is a phono jack. Power up the QRM Eliminator. Start with the phase knob at the 12:00 position. Adjust the two antenna gain knobs until you are getting equal signal level on each. Next, adjust the phase control to minimize the noise. Finally, fine adjust each antenna gain knob to see if you can minimize the noise even more. If so, adjust the phase knob once more for minimum noise. I hope this helps.

[@hamidch632]

@@n4hnhradio i have a yaesu ft80c and it has a ptt labelled port at the back that is RCA type . , so this port will be the one connected to PTT of qrm eliminator ?

[@n4hnhradio]

@hamidch632 Yes, and make sure when you transmit the radio you hear a relay click inside the QRM Eliminator. That indicates that the QRM Eliminator is protecting the antenna inputs from RF power. That’s the purpose of this connection. Certain QRM Eliminator models have a TX light to confirm the PTT signal has been received.

[@mikewalsh511]

What path does the RF take inside the QRM eliminator when the PTT isn't triggered? How does it not blow up?

[@n4hnhradio]

It will blow up eventually. The RF doesn’t get diverted away from the receiver circuit if you don’t provide a PTT connection. That is why I made this video. I damaged mine to make this video.

[@sm6yec]

Can you use VOX whit this setup ?

[@n4hnhradio]

Not very well.

[@kd4exy]

The Heil fs2 has been disconnected. A new fs3 is only one they have

[@n4hnhradio]

The FS-3 only has one switch/cable. It won’t work for the QRM Eliminator. I already made a video about the FS-3.

[@CBRadioWayBack10-4]

who cares, it's a video about the QRM eliminator.

[@n4hnhradio]

The Heil FS-2 is the easiest way to provide the required PTT signal to the QRM Eliminator. I spoke about it in the video. That’s why @kd4exy mentioned that the FS-2 has been discontinued. In fact, it was only discontinued a few months ago. I’m sure @kd4exy meant to type “discontinued”, not “disconnected.” Some newer transceivers do not have a TX GND connection that provides the dry contact for the PTT signal via an RCA cable. A special (usually 8 or 10 pin DIN) cable must be made and connected to the Tuner or Linear port, which prevents those ports from being used for their intended purpose. It’s especially bothersome with transceivers like the FT-710, which has one port that you must choose in the menu to either be for keying a linear amplifier or operating an antenna matching unit.

[@Nick_G7IZR]

Try RM Noise, the AI noise reduction. Works brilliantly.

[@n4hnhradio]

Yes, I’ve heard the RM Noise software demonstration. Not bad but I still hear a remnant of the noise, and the received audio is adversely affected. Phase cancelling the noise before it ever reaches the radio is still the most effective approach. As I show throughout my videos, it is best to attack noise in the front end of the receiver first, before it even gets to the second IF, or SDR stage, and especially before the DSP stage. But, it’s even better, to stop it before it enters the radio, like the phase cancellation devices do.