In 2019 I organised a trip to a remote farm in Devon for a mini DX-pedition, a sort of radio holiday for a few good friends and club members to play radio non stop for 5 days with 10 acres of field to erect antennas and a non existent HF noise floor. We took three Kenwood TS-590SG sets with us and I was amazed with their performance in a multi radio environment. One was running QRO via an Elecraft KPA500 amplifier and there was never any problems with interference between the operating stations. At one point, we were working CW on 20m @ 100w using a ZS6BKW and working SSB on 20m @ 100w using a DX Commander with around 15m separation of the antennas with no issues. The only slight interference issue we had was if another operator was using an exact second harmonic but even then, most stations were still workable.
Now, onto the IC-7300. I’ve always liked this radio and thought it would look great in the shack sitting with my IC-9700 but I’ve also heard that it’s not great when used alongside other HF radios. It’s not a real problem for me since I only want to own one HF radio and I don’t have any very close amateur neighbours but I do enjoy operating alongside others at special events and hope that our mini DX-pedition will be come a regular event so I need a radio that can cope with strong, close in signals. I don’t want to keep both the TS-590 and the IC-7300 but I do have both in my shack so thought I would do some very basic tests to see how the IC-7300 handles close in signals using the TS-590 to TX. Most content that I have read says that the IC-7300 is pretty bad with close in signals but none seem to back this up with any real world tests, just the odd “I used it at field day and it was good/ok/not great/rubbish”.
I have the IC-7300 connected to a Loop on Ground RX antenna which is 15′ square and used in my station for low noise RX. It works well but more about that in a later post. The TS-590SG is connected to a 130′ inverted L fed via an SGC230 ATU at the feed point and two, 10m long radials plus an 8′ earth rod. The Loop on Ground is directly under the middle of the TX antenna, around 8m below. It’s a pretty rough “worst case” antenna if you were trying to get some RX/TX antenna separation so pretty useful for this test. To test, I place the IC-7300 on a band and tune to the FT8 frequency so I can decode some signals. I then place the TS-590 on the lowest band (making sure not to be an exact multiple of the frequency that the IC-7300 is using since that would be a little extreme!) and send a 100w CW carrier. I check the IC-7300 for any visible overload/interference and check the FT8 decodes to see any noticeable reduction in RX performance.
Well, my very basic results show that the IC-7300 is 100% fine so long as there’s a clear band between itself and the TX radio. For example, if the TS-590 is operating on 40m, the IC-7300 can use all bands except 60m, 40m and 30m. 60m and 30m are usable but require some RF Gain reduction to prevent overload where as 40m is unusable. This seems to be the same for all bands. I was expecting much worse so this is a nice finding. Being able to use adjacent bands with a very small performance loss is probably acceptable for most situations.
What if I use some external filtering? I have a set of 5B4AGM band pass filters for HF so decided to put them inline to see if things improved. I found that with a band pass filter on the IC-7300, it could work all adjacent bands with no impact on performance (other that the insertion loss of the filter) without needing the RF Gain to be adjusted. The only exception to this was when operating the TS-590 on 60m while attempting to use the IC-7300 on 40m.
So, there it is. A simple, real world test of using the IC-7300 in a multi radio environment. I’m quite impressed by it’s performance without the need for any external filtering and I bet that any adjacent band overload issues would be mitigated with some better antenna separation. As for my IC-7300, it will have to find a new home as I much prefer the TS-590SG performance when sitting almost on top of another station and I really need the dedicated RX antenna input to overcome my high local noise but the IC-7300 is fine for the normal, casual operator so long as you have a few 100 meters between stations and don’t mind not being able to work on the same band (although the TS-590SG has to be at different ends of a band anyway so no Data and CW working!).
Thanks for the information. A very interesting ‘real world’ review.
Hello Matt,
I wonder if you have noticed any induced noise/interference to your loop on ground from the main transmit aerial. Have you tried grounding or disconnecting main aerial.
Having tried many different RX only aerials, K9AY, BOG, LOG, passive loop, tuned loop, mini whip, a steerable amplified loop seems to be the best solution here. Like most of us the aerials are too close and it is easy to see interaction between them!
Hi Nigel. Do you mean any interaction when receiving? I’ve not noticed any but I’ll disconnect and ground the EFHW and see next time I use the radio in anger! I don’t usually run 2 HF sets or work split band at the same time here so it’s not an issue that I worry about much. The main reason for this quick and dirty test was to see how well the IC-7300 performed when working very close to other radios in a field day or special even environment. My LOG seems to work well with a good decrease in noise and an increase of around 3 to 6dB SNR on the higher bands. It’s only 13′ x 13′ so I plan to make a bigger one (25′ x 25′) soon to see if it helps with the lower bands. I’ve also tried a Wellbrook Loop, WellGood Loop (Wellbrook clone) , PA0RDT Mini Whip and now I have a Bonito Megaloop FX to test. My quest for a QRM busting low noise RX antenna continues! I plan to write another blog post about my misadventures with RX only antennas very soon.
Yes Matt, sorry should have made it clear, any change/improvement or otherwise when using your LOG on receive if you disconnect/ground (de-tune) your main aerial (or any other).
When listening for weak signals or trying to improve signal to noise ratio I notice that de-tuning other close by aerials may enhance or detract from the wanted signal.
No problem Nigel. I thought that was where you were going. I’ll have a go at earthing my main TX antenna and see what happens. I guess it could be acting as a sort of parasitic element.