When I traded my Xiegu G90 and my RS-918 for a KX3, I missed having a panadapter. I’m a ragchewer, not a DXer or contester, but I like to be able to view and track what is going on around the band. My casual use hardly warrants the $700 price for the Elecraft PX3 and I don’t want to rely on a computer, so I searched for alternatives. What I found surprised me with its simplicity and inexpensive price. It does rely on an Apple product such as an iPhone or iPad but should be adaptable to most other SDR rigs with an I/Q port.
The panadapter is based on the inexpensive iSDR app, available through the Apple app store. Here is a list of what is needed:
*iPhone, iPad or iPod Touch. (Basic requirements are on the website provided below.)
*iSDR app ($.99)
*USB adapter for the above.
*External sound cord with stereo mic input (note that most have mono mic connections). I used this one from Amazon ($26.99): StarTech.com USB Sound Card w/ SPDIF Digital Audio & Stereo Mic
*Adapter from 3.5 to 2.5mm stereo connector (for the KX3 I/Q input).
*Stereo cable (3.5mm) to connect sound card to rig.
To set up, connect the sound card to the I/Q input (RX I/Q on KX3) using the stereo cable and adapter, and the USB connector from the sound card into the USB adapter. Connect the USB adapter to your Apple device. Enable the I/Q connection in your rig (KX3: Menu RX I/Q to ON)
Turn on your rig, then start iSDR. You will need to enter the center frequency of the band you want by going to the I, bottom right, then finding the line that brings up a box to type in the frequency. At the center bottom of the screen is a button to turn on the app. It should begin to display the band (22kHz each side of the center frequency). By tapping various places you can change the bandwidth, mode, etc. You can also move the center frequency line with your finger.
You will probably want to go to Settings on your device, open the iSDR settings, and make some adjustments. For example, you can choose between three AGC settings. I also found it helpful to lower the signal floor.
More information about the iSDR app and how to use it may be found at https://apps.digitalconfections.com/?page_id=739#iSDRiPhoneApplication
This definitely isn’t a PX3, and does not control the rig. However, as you tune you will see the display shift according. You could also monitor one band while operating on another. I have not enabled sound in the iSDR app, but if you do, it will function as an SDR receiver.
It does use a lot of resources on your Apple device, and I have found that I cannot charge the device (my USB adapter allows my charge cable to be plugged into it) or even have the charge cable connected while using the rig because it introduces noise through the I/Q port.
Sure, it would be nice to be able to click on or touch the frequency you want on the band and have the rig respond, but for my purposes, that’s a minor issue. I can monitor that part of the band that I usually frequent and easily tune the rig to where the activity is.
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