MFJ-1708SDR review - Share your antenna between your transceiver and an SDR

Thank you so much for the detailed description and options on how to connect an amp. Looking at the diagram for the AL-80B, it looks like I will need to put a diode in line before the Relay connection.

 

You should not need a diode on the amp, Because the MFJ-1708SDR has one.

But it would not hurt anything to add one, If you can live with the 1 diode voltage drop.

 

Nice item. I brought home an SDRplay on Sat and was greatly disturbed by the warning that having the SDR too close to your TX antenna will blow up the unit and void the warranty. Naturally they didn't bother to define what "too close" is.

I am operating a 40M dipole or a vertical long wire and 100 watts on the side of the house. The SDR / Discone is in the back of the house, about 20 feet from one of the 40 meter wires. So far I have yet to blow it up...

 

I've got an SDRplay as well. I unplug the antenna from it and it picks up my TX on the QRP rig. Delay is <1s. Not blown up yet.

I plan to use one of these eventually, built into the transceiver box.

http://www.qrpkits.com/ezseries.html#eztrsw

There will be an extra BNC on the back of the box that will go to the SDR. I've got the cheapo RTL-SDR Blog dongle that I don't mind putting at risk for shaking down the concept.

 

Just picked up mine yesterday. It has a plastic case (everything else I have from MFJ is metal) and works as intended.

 

I must be brain dead today as this is just passing over my head.. I have a 706MK2g and I'm trying to figure out where I am tying the PTT plug to. I have the RCA plug wired at about 3
long as to where the radio sits from the antenna and I am drawing a blank as to what pins I am tying this to? Do I go from ground to the Hsend/PTT pin #3 on the back connector or where am I tying it to??

 

Good video. It is a good stuff from MFJ solving all waterfall issues where some of the modern transceivers do not have an IF output.

 

You would connect it to the same connection that would be used for keying a amplifier.

 

Thanks..
Need to find my manual now..

73 Rick