Receive only antenna with Rx2 with io board

[Randal Warren]

Is it possible to use RX2 for a receive only antenna like a magloop. It would be on the same frequency as my transmit frequency. Would this overload the ADC? Could I use a TX/RX relay to prevent overload? Or is RX2 switched off during tx anyways.

Thanks

Randal

VE7NHW

[Steve Haynal]

Hi Randal,

Yes, it can overload the ADC but likely won't harm the radio. There is a setting which automatically reduces the LNA gain during transmit. I have mine set to the lowest value which is -12dB. This reduces potential overload during transmit. I know where the setting is in Quisk but not other software.

RX2 is meant for full duplex use. There is a setting to keep the TR in transmit and then the user can use RX2 for the receive path. See the schematic for more details.

www.hermeslite.com

73,

Steve

kf7o

[Randal Warren]

I think my confusion is coming from the button RX2 in Thetis. I've looked at the schematics trying to figure out how it all works. I guess what I'm trying to do is attach my receive only antenna to RF3 and operate in MODE 2. So pure signal still works. Then am I able to view RF3 on RX2 in thetis?

It also looks like there is some type of filter that can be applied to J9 what is it?

Also what's the point of RF1 i dont really understand what use it has.

Thank you.

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[Mike Lewis]

The HL2 receivers are all on the same antenna with a single ADC. That RX antenna can be on various ports, but only 1 at a time.  

Some other SDR hardware have multiple ADC with dedicated front end RF hardware.

Mike K7MDL

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From: herme...@googlegroups.com <herme...@googlegroups.com> on behalf of Randal Warren <rand...@gmail.com>
Sent: Friday, July 11, 2025 12:41:44 PM
To: Steve Haynal <softerh...@gmail.com>
Cc: Hermes-Lite <herme...@googlegroups.com>
Subject: Re: Receive only antenna with Rx2 with io board

 

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[Randal Warren]

Slowly starting to understand. So if I'm understanding correctly, if I enable Mode 2 on my IO board it will then only receive on RF3 and Transmit on the main antenna. This isolation of the main antenna is done by the io board sending a INTTR signal to keep the main antenna on the TX path only.

If i have Mode 2 Enabled during Transmit wouldn't my Receive antenna (RF3 J9) be grounded and the Puresigal (J10) path take over? So no worry about overloading the ADC?

[Dalton Williams]

I am interested in this also.

Dalton Williams

DeFever 41 MV Easy Living

20 Years & 34,800 Miles on the water

Amateur Radio W5EIM

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