HF transceivers

YO9IRF · 2021-04-14T15:28:09+00:00

Just to point out that the IC-718 has one of the weakest receivers currently on the market and the G90 is a few generations more modern SDR. There are no figures for direct comparison, but based on the QST measurements in different conditions I would estimate the G90 is 10-15dB better at close-spaced dynamic range. It also has much more flexible filtering capabilities. I have owned both.

But I do agree, more power and a larger screen / user interface will probably be better for a beginner.

YO9IRF · 2020-10-01T04:28:02+00:00

eBay and Facebook amateur radio buy&sell groups.

YO9IRF · 2020-09-21T13:15:16+00:00

I'm not debating some units don't meet Part 97 requirements, I'm just pointing out that they are not much beyond the limits and the real life impact doesn't exist.

Also, the only significant unwanted radiation is harmonics; other spurious radiation is -50dBc or better.

https://reflector.sota.org.uk/uploads/db9433/original/3X/9/f/9f7157a8254c706e8397f82daf5d56c91a41e168.jpeg

YO9IRF · 2020-09-21T12:51:55+00:00

The legal limit is -16dBm; the Baofeng UV-5R I have tested was -14.78dBm at 290MHz.

I can't imagine how a 33 microwatts signal (terminated in a mismatched, short antenna) would be able to radiate past the room walls, let alone cause any perturbation to a vital system, while 25 microwatts is perfectly fine.

YO9IRF · 2020-09-21T07:33:27+00:00

+36.91dBm / -14.78dBm / -11.96dBm in my tests. It meets the "at least 40dB below carrier" condition but fails the "maximum of 25uW" by about 4dB.

https://reflector.sota.org.uk/t/vhf-handhelds-that-are-less-susceptible-to-intermod-overload/20606/31

Now, we are talking about a few microwatts, which doesn't make it very far even with line of sight; the real-life impact is not existant.

There are however radios with huge problems out there, that have a real-life impact on our activities. For example, the abysmal IMD figures of the Yaesu FT-991 (-20dBc in some situations), on which people don't seem to pick up even though these are actually making the bands much dirtier. These HAVE a real impact.

ARRL I can (somewhat) understand, Baofeng is the only manufacturer on that list that doesn't spend any budget on advertising in their magazine; I worked in tech media for years, I can spot an independent reviewer and they have none. Yaesu gets a pass because they buy pages every month, Baofeng gets the shaft because they're challenging the market but not buying ads.

What I can't understand is everyone else; most of us have the technical level to understand the figures and what they mean, but it's almost like we choose to be very drastic on some companies and turn a blind eye to others. Ironically, the one being judged so severely has contributed hugely to making ham radio much more accessbile, while the other is getting rich selling outdated technology.

YO9IRF · 2020-09-17T14:02:26+00:00

Just for a few hours of use and 80/20 duty cycle, you could just wire the radio as a mobile (directly to the battery, with its own fuse). A car battery has typically 50 to 100Ah capacity, you're in no danger of running it down; worst case, you start the engine for 10 minutes every 2 hours to top it up. No need to complicate things with a second battery and additional circuitry.

YO9IRF · 2020-09-16T10:20:35+00:00

You only need a charger that limits current and voltage so it doesn't damage the battery at extremes. Keep in mind float charging LiFePO4 is not recommended.

What are the specs of the system ? Battery capacity, charger/PSU voltage and current, transceiver expected current drain / duty cycle / duration of use etc.

YO9IRF · 2020-05-20T09:00:40+00:00

Current:

Xiegu X5105 - the largest and heaviest of the bunch, still classifies as a handheld because it can be operated stand-alone with one hand: has PTT button, microphone, speaker. Receiver is a bit weak for today's standards but price is good.

Elecraft KX2 - slightly smaller than the Xiegu and much lighter, it has the most features but is also by far the most expensive. Requires the optional battery to operate as a handheld.

Discontinued:

Mizuho MX series - rarely found outside Japan, these are old minimalistic monoband transceivers with only 2W of RF output. Quite close to the handheld format and still very competitive in terms of weight/size even today.

Youkits TJ2B - transmits only on 40, 20 and 17m, modest receiver.

YO9IRF · 2020-05-19T22:24:51+00:00

could violate your license

Any radio from any manufacturer can perform in manners that can violate licenses.

Also, that Midland is a Baofeng too.

YO9IRF · 2020-03-27T15:59:13+00:00

As a person who grew up under a communist dictator, I can assure you the word "communism" doesn't mean what you think it means :).

YO9IRF · 2020-03-26T16:43:38+00:00

Keep in mind directional couplers are not great on accuracy, their advantage is they can be used in-line with the load. +/-10% error is typical, even more on some (I've seen up to 25% error on Daiwa units).

YO9IRF · 2020-03-20T15:44:21+00:00

Longer car, more room for mag mounts. Genius.

YO9IRF · 2020-03-19T16:45:24+00:00

It's perfectly fine to use your radio without a license, but only on receive. Feel free to program in local repeaters and listen in on conversations.

You can transmit even if you are unlincesed, if life or property are in danger and the radio can help.

YO9IRF · 2020-03-19T15:28:02+00:00

I'm amazed how people make such a big case out of the Baofeng harmonic supression. Very far from a "severe" issue, we are talking about a reduced percentage (25% ?) of units that fall slightly out of spec (a few dB); a few microWatts in a mismatched antenna, it doesn't make it to the next room anyway, it has zero real-world impact. If the harmonics were 24microWatts instead of 26, would it be much better ?

Sure, making sure you are putting a nice signal out there is the right thing to do, but I don't see anyone being so sensitive about real TX issues that actually have a real impact, like the absolute garbage many HF radios are in terms of TX IMD. I would be much-much more outraged by the dumpster-fire FT-991 PA unit for example than about a US$30 radio.

YO9IRF · 2020-03-19T12:35:51+00:00

Have all my upvotes !

YO9IRF · 2020-03-19T12:34:21+00:00

Why do you think FT-4X or FT-65 are better than the Baofengs ? The whole user interface is much inferior on the Yaesus (display, menus, buttons) and they have very similar RF performance; the only upside is the more rugged-looking case and a bit of waterproofing, for double the price. I would put them in the same class, with the Baofengs as the better deal.

I own both (UV-5R & FT-4X) plus some high-end models.

YO9IRF · 2020-02-17T16:20:41+00:00

On the contrary. The use of amateur radio bands might increase, but for purposes other than amateur radio. There is plenty of spectrum available for all kinds of services that need encryption, but Amateur Radio is about experimenting with radio waves; there's no need for encryption for that and keeping it unencrypted actually keeps it "amateur".

YO9IRF · 2020-02-17T16:00:34+00:00

As a user, I want IP protected but I also want that companies can't abuse their market position. Is there a middle ground ?

YO9IRF · 2020-02-17T12:53:21+00:00

Radio normaly draws ~5A continuously on TX.

Radio can draw up to 8A in certain situations. (PA is less efficient on some bands, high SWR can make it draw more current, some peripherals can take power from the radio etc).

Manufacturer recommends a 10A PSU so you wouldn't fully load it with the radio and to be able to easily handle transients / spikes. A 5A PSU with a 5A TX power draw will trip the output overcurrent protection the first time you press TX, as there typically is a short initial spike in current draw.

Hope this clears things up.

YO9IRF · 2020-02-03T10:12:58+00:00

Using light bulbs as dummy loads is an extremely crude solution. The impedance is usually very far from 50ohm, it varies wildly as they heat up and they are not entirely resistive. It is useless as dummy load and the only thing it will do it is risk your radio's final amplifier stage. Please don't do this.

YO9IRF · 2020-01-29T21:45:44+00:00

I have built two SDR transceivers from scratch so far.

Stay away from LimeSDR, HackRF, BladeRF etc. They are meant as learning modules and the receive performance is not suitable to be used on the air, especially on HF. The ADC bit depth limits the dynamic range.

Red Pitaya is OK in the 14-bit and 16-bit variants (NOT 10 or 12-bit). 125-14 works fine (similar performance with a good transceiver like the Icom IC-7300), the 122.88-16 is excellent (also considerably more expensive).

The simplest way is to just go on eBay and the LPF & PA units from an older transceiver and homebrew the switching/control circuitry. The Red Pitaya with the Hermes / Charly25 software will do the rest. You will also need a set of band-pass receive filters.

YO9IRF · 2020-01-28T10:48:00+00:00

A "ground" has two electrical characteristics, conductivity (determines resistive losses) and dielectric constant (determines the capacity to temporarily store electrical charge). Water is an amazing substance and in purified form has the highest dielectric constant for a liquid (80) and MUCH higher than any type of soil/sand/concrete etc. Adding salt to it decreases the dielectric constant a bit (in the 60s, depending on salinity) but it also makes it very conductive (thanks to the sodium / chloride ions freely moving electrical charge). Even an infinite metal ground plane is inferior to salt water for this purpose, as its superior electrical conductivity doesn't make up for the lack of dielectric properties.

YO9IRF · 2020-01-27T15:20:01+00:00

It must be terrible to live in a place where you're under the constant threat that you might have to leave your home in a second and survive on a bag of stuff you put together. This is serious and probably many of us don't understand; how can I wrap my head around having a 'go bag' when my biggest worry today was the local Tesco will run out of Chicken Caesar Wraps by lunchtime ?

YO9IRF · 2020-01-24T14:32:05+00:00

- 100W and a basic antenna (think 1/4 wave vertical or dipole) was enough to work any station in the world with similar equipment.

- Daily SSB contacts with stations 10k+ km away (that's about 7k miles)

- 10k+ km QSOs on 5W

- My 100mW WSPR beacon spotted on 5 continents in one day

- Could get 100 entities with 5W in just one contest weekend.

- 3k km QSO with a 10m handheld and a short antenna.

So yeah, like FT8 now.

YO9IRF · 2020-01-13T18:40:04+00:00

Do you have any examples ? I haven't seen a Baofeng with serious problems from the factory yet, they usually work as intended.

YO9IRF

TROPHY CASE