I was looking for a way to compare the performance of VHF/UHF handhelds and find the key indicator that would be relevant for summits that have strong broadcast interference. I realised I don’t need to reinvent the wheel and test dozens of radios, the data is already out there: QST has tested most of the popular handhelds, and the measurement for 3rd-Order Dynamic Range (10MHz) is exactly what I need.
So, being too lazy to go outside this morning, I went to my ARRL account, downloaded all QST tests of handhelds and centralised performance measurements in one easy to use table. It’s sorted by “3rd DR wide 2m (dB)” by default but you can sort by other criteria if you want, or just search for your favourite model.
Without further ado, here it is:
On older products there is no data for 10Mhz spaced 3rd order Dynamic Range unfortunately.
I looked over those numbers and it is clear that they don’t know what they are talking about.
There is a big difference between adjacent channel rejection and overload rejection. When trying to operate 2m SOTA from a populated hilltop, you want overload protection. That is to say, ability to still receive a weak signal on a frequency just one or two MHz away from a very nearby 100+ watt transmitter.
Those QST numbers show that SDR chip receivers of the chinese cheapo radios on par or better than radios with tuned circuits. False reporting!
It also appears they just looked up published best case factory specs instead of testing every radio themselves. Here in the USA, we now call that “fake news”.
QST tests radios in their own lab. They do not just print factory specs.
The measurement for “3rd DR wide” is the one for out of band rejection. That is a 10 MHz spacing (wider than the 2 m or 70 cm bands) two-tone, 3rd order dynamic range measurement.
The Yaesu FT-50R measures 90 dB for this, while the FT-4XR, which uses the same chipset as the Chinese radios, measure 65 dB. That measurement is probably an upper bound for the inexpensive Chinese HTs, since the FT-4XR has been reviewed with somewhat better RF performance.
But they are still missing the point. Putting an ht on a service monitor and tuning 10 MHz. away and generating a signal and then measuring the signal level required to break the squelch is not going to tell you what the overload rejection is!
When I test receivers, I generate an on-channel signal and measure the injection required for full quieting. I then run the generator down to half that value and make sure I still have 20 dB or better quieting. I then generate a signal off-frequency by a certain amount (I like to use 10 MHz. for 2m radios) and slowly increase the off-channel signal level until the quieting of the on-channel signal changes. THAT is the level of overload rejection that is important to us 2m SOTA operators.
I have yet to have any of the radios that use the RTL SDR chips for receiver show any useful overload rejection of any kind. Most of them begin to crumble with even the slightest off-frequency signal injection.
Meanwhile, the Radio Shack HTX-202 and the Icom IC-2A are still the rock stars with no loss of sensitivity or decrease in quieting with as much as 10,000 uV off-frequency injection. Those two radios have the best 2m out of band rejection I have seen cross the K6FRC lab bench so far.
Those figures agree very well with my real world experience of using many radios on commercial sites. I’ve lost track of the number of times I’ve told people to consider these radios FT60, TH79, VX170, radios I have used on sites and had no issues and there they are nearly at the top of the table. I had an FT-470 many years back, awful thing, there it is near the bottom.
So whilst you are free to point out errors in the methodology etc. and better measurement techniques, the published chart agrees very well with my experience.
I use the Icom AA battery pack for the IC-2A and IC-2AT SOTA radios. They are still found on the online auction sites. The packs take 6 standard AA alkaline batteries. The pack for the Radio Shack HTX-202 takes 8 AA cells (Icom IC-2A and HTX-202 use exact same battery packs, so be sure not to put the 8 cell pack on the Icom! The voltage is too high.) I never, ever take rechargeable packs with me for SOTA activations anymore. They have let me down too many times! I take 2 of the AA battery packs and have only had a problem once when I dropped one and the batteries made an effort to escape.
I just install new batteries before going to a summit. After the activation, the pack I used gets opened and the lightly used batteries are “recycled” and installed in the many flashlights located around the house and shop. No waste!
It is theoretically small and light enough for SOTA. Yaesu advertise it as having an excellent large signal handling capability due to the design with a special front end filter. It is also cheaper and many times more powerful than a lot of HTs. If I did nothing but FM for SOTA, I would be tempted to buy one.
73 de TF/OE6FEG/P
3rd-Order Dynamic Range (10MHz) test data may not represent real operational conditions on the summit. Interference can be from HF broadcast stations, and the power level may be much higher that used in 3-rd-Order Dynamic Range (10 MHz) test.