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Author Topic: Question: Using SDR dongle with rig while transmitting  (Read 6347 times)
N5INP
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Posts: 755




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« on: August 30, 2013, 05:41:04 AM »

I've got a SDR working with my NRD-535, just to see if I could get the two to talk using Omnirig and it works OK as far as the radio controlling HDSDR. My plans are to use the PC/HDSDR as a pan adapter with a HF rig when I get one. I will use a long wire ant. for the SDR and a dedicated HF ant. for the rig (is there a better solution)?

My question is: How do you protect the RF front end of the dongle when you transmit? I'm imagining I'd have to put a relay at the front end for the dongle so it's ant. is disconnected while transmitting? I'm sure this problem has been solved since I see people doing this type of setup on You Tube but I haven't seen how they are wiring the antennas up.

Thanks.
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K9AQ
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Posts: 54




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« Reply #1 on: September 01, 2013, 05:06:50 AM »

I use a DVB-T dongle and an upconverter with a homebrew switch box to share the antenna with my Kenwood TS 480.  I used basically this design http://www.lz1aq.signacor.com/docs/Integrating-Software-Defined-Radio_II_HP_eng/Integrating%20Software%20Defined%20Radio_II_v41.htm

I didn't use the audio switching because I use the SDR only has a panadapter.

I have had this working for quite awhile and it works well.

Don
K9AQ
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N5INP
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« Reply #2 on: September 01, 2013, 04:15:39 PM »

OK thanks, I'll take a look at the schematic. I'm not sharing antennas though, so my solution might be as simple as a relay to just disconnect the dongle ant.
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WE1X
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Posts: 317




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« Reply #3 on: September 07, 2013, 05:31:54 AM »

Stefan (VE4NSA) wrote a paper on how to do a very simple, non-invasive and reversible mod to the Icom 7600 using a Mini-Circuits splitter, DVB dongle and SDR#.  I used his hardware mod in conjunction with HDSDR and was able to achieve point-and-click control of the 7600 via HDSDR's spectrum display. Works great. I wrote a paper on how to do this. If interested simply e-mail me and I will send. BTW with the help of Mario (HDSDR's keeper) I was able to integrate it with HRD/DM780.  Others have done something similar with various Yaesu rigs.

Harry WE1X
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WV4I
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Posts: 136




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« Reply #4 on: September 08, 2013, 03:53:48 AM »

The MFJ-1708 is a reasonably effective external T/R relay, for the $$s. It employs a mini mechanical relay, and from looking up the data sheets of some of the key components, guessing 100w max thru it. If using an amp, simply place the 1708 between the exciter and amp, as the amp has its own T/R relay as well. This config would be where have same antenna xmt and rcv. You may still see some overload on SDR as most T/R and antenna switches isolate to the tune of -60db, not disconnect. Recommend front end protector for SDR unless it costs more than SDR hardware.
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