Thursday, 3 February 2022


Connecting your SDRPLAY to your IC-7610

With previous radios, I have shared the antenna with my SDRPLAY device via an MFJ-1708B which has certainly worked, but it's messy and you never feel 100% convinced that it's going to protect the front-end of your external receiver. The best way to protect it is to not put it in harms way in the first place and you can do that if your radio has a suitable connector. Some transceivers (like the FT-DX3000) have a very simple RF-OUT connector which means that you just plug your external receiver into that connector and hey presto, it works.

The Icom IC-7610 has a different arrangement. It has RX-IN/RX-OUT BNC sockets on the back which form an RX loop, allowing you to insert a receiver inline. This means that you are never putting your SDRPLAY (or whichever receiver you use) at risk. I thought originally that I could just plug my SDRPLAY into the 7610's RX out, but when I did, I got nothing!  Apparently, you need to place the external receiver into the loop using a splitter (see the diagram that I sketched above).

Why Icom chose this method over the simpler one employed by Yaesu on the FT-DX3000, I have no idea. Presumably there's a benefit or it's due to the fact that the IC-7610 has Dual Receivers and very comprehensive antenna switching capabilities - I don't know.

By using a high quality splitter such as a Mini-Circuits ZCS-2-2+ or a Diamond SS-500, you can be assured that you are also providing a good degree of isolation between your transceiver's receiver(s) and the external receiver. Typically, you're talking about more than 30dB isolation, so there's very little chance of interference from one receiver to another.

At the time of purchase, the Mini-Circuits splitter wasn't available anywhere in the UK - fresh stock wasn't expected for another 3 months, so I turned to the Diamond SS-500 which is beautifully made but at £80 is horribly expensive. The Mini-Circuits device cost around £60.  As usual in these Covid times, stock shortages pushes prices up to ridiculous levels, and you have to choose between stumping up the cash or waiting months. I chose the former.

Although the price was higher than those retailers who had no stock 😲 RadioWorld were quick to deliver - it arrived the very next morning and was well packaged. 

The Diamond SS-500 is good from 0.5MHz up to 500MHz which falls way short of the SDRPLAY's frequency range, but that's of no consequence to me, since I'm only interested in HF coverage. 

Before I could install the splitter, I needed to make up some BNC-PL259 coax leads and a PL259-SMA lead. Once that was done, I somehow managed to connect them all up without pulling out the IC-7610 from its tight-fitting place on the shelf - miracle!!

I then loaded the latest version of SDRuno along with all the various add-ons and also made sure that OmniRig was running and configured for the IC-7610. 

With everything setup correctly I switched on the radio and ran RSDRuno. The two interfaced perfectly and it was good to see the full layout and tools of SDRuno instead of the very limited EXTIO version which I'd tried previously with limited success.

Version is the latest version of SDRuno at the time of writing and is incredibly rich in features. There are a couple of bugs, but the software writers are fully aware of them and are working hard to sort them out. One of them relates to an issue which I personally experienced when trying to use the IF Output of the 7610 through the USB3 connector. It meant that you were unable to click on SDRuno's Scope to tune - you had to use your mousewheel or direct frequency input. That, ultimately, led me to go down the RF path. Hopefully, the patch isn't too far off for those who want to use SDRuno with the 7610's IF Out without an external receiver.

Anyway, the software ran perfectly and it feels good to have SDRuno back on screen, especially this latest version. Things have changed significantly since the last time I connected an RSP to the radio and I'm looking forward to exploring and experimenting.

Below are a couple of images showing the Diamond SS-500 and RSP1A hidden away under the radio shelf and then there's a screenshot of the software up and running. Conditions are poor at the time of testing, so there's not a great deal going on in terms of signals. I’ll post more when conditions (and activity) improves.

If you don't have an external receiver such as the RSP1A and don't want one, you can, of course, use HDSDR as instructed in the IC-7610 Manual. It provides you with a simple panadapter which works very well.  You don't need anything other than a USB3 lead.

Needless to say, SDRuno through an RSP provides you with a staggering range of functions and features to explore and experiment with. You pays your money and make your choice.

I'd be interested to know what you have opted for!

If you have any comments or questions, leave them below. Thanks for visiting the blog. 73, Tom, M7MCQ.

icom ic-7610, sdrplay, sdruno, rsp1a, rspdx, rspduo, diamond ss-500

1 comment:

VE9KK said...

Good evening Tom, very much enjoy reading about your radio adventures. Glad your still sticking it out with the Icom 7610.