Arguing with a machine: ChatGPT and me

Posted on March 17, 2023 by Kevin

I write about radios a lot, and use the abbreviation MHz and kHz with frequencies, but I’ve always wondered why one is capitalized and the other is not. I asked ChatGPT:

Why is the first letter of the abbreviation MHz usually capitalized, but the first letter of kHz is not?

ChatGPT replied:

The reason for this difference in capitalization between “MHz” and “kHz” has to do with the SI (International System of Units) rules for unit symbols.

In the SI system, unit symbols are always written in lowercase letters, except when the symbol is derived from a proper noun. In the case of “MHz”, the unit is derived from “megahertz”, which is a combination of the metric prefix “mega-” and the unit “hertz”. Since “mega-” is a proper prefix derived from a Greek word meaning “great”, the first letter of the symbol “MHz” is capitalized to indicate this derivation from a proper noun.

On the other hand, “kHz” is derived from “kilohertz”, which is also a combination of the metric prefix “kilo-” and the unit “hertz”. However, “kilo-” is not a proper prefix in the same way that “mega-” is, so the symbol “kHz” does not capitalize the first letter.

It’s worth noting that while these rules are widely followed, there may be variations or exceptions depending on the specific context or style guide being used.

I didn’t quite follow the rationale, so I asked a follow-up question:

So why is “kilo-” not a proper prefix, but “mega-‘” is?

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My favorite shortwave radio

Posted on March 17, 2023 by Kevin

My very first website had this heading:

Find out who I am by reading my web site
and I will find out who I am by writing it.

I’m writing this article to help myself answer the question of which is my favorite radio.

I have 37 radios right now. Some are super cheap (under $10), some I couldn’t give away on eBay, some are novelties, and a few are serious radios. The candidates for favorite shortwave radio come from the last category, and they are:

  • Eton Elite Executive
  • Sangean ATS-405
  • Tecsun PL-330
  • Tecsun PL-660
  • XHDATA D-109
  • XHDATA D-808

Eton Elite Executive

The Eton Elite Executive is the most expensive of these radios to buy (except I got it on a blowout sale under $80). It not only performs well, but it is also feature rich, including MW/FM/SW/LW/AIR, plus SSB and FM RDS. It has a convenient “scan for next station” function.

What I don’t like about this radio is that it falls over easily, and that the case is awkward to remove because of the antenna placement. I also don’t like its station memory system. Its automatic key lockout is also extra trouble. Auto tune storage (ATS) only works on FM. The F1-F7 keys do many things, and you need the manual to know what’s what. Other radios use the number keys for settings and include descriptive labels.

Eton Elite Executive radio (Amazon product photo).

Sangean ATS-405

The Sangean ATS-405 is a radio that I keep coming back to. It has a wonderfully clear display. The carrying case is efficient. It has excellent performance on MW. It has a convenient “scan for next station” function. It has controls for soft mute, tuning mute, AGC and squelch, but it lacks some things, like LW, Air band, SSB support, FM RDS and an external antenna jack. Also ATS is limited to MW and FM (and the number of memories per band is only 36). Shortwave sensitivity is the lowest among the contenders. A manual is required for some features.

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XHDATA D-808: Good performer, but could be better

Posted on March 15, 2023 by Kevin

The XHDATA D-808 arrived yesterday afternoon. My first impression, just fondling the radio, was good. It was solid and the materials seemed better than average quality. After some time using the radio, I was less impressed. I detail below how the radio has excellent performance as a radio, but that its operation and documentation are poor.

XHDATA D-808 Shortwave Radio (click to enlarge)

Upgrade

It appears some changes have been made since the XHDATA D-808 was initially announced in 2018. In 2021 the display back light was changed from white to amber. Other users have experienced the antenna coming loose from the circuit board, which apparently was the only anchor point for the antenna. Now there is a screw through the back of the case that holds the antenna more securely. (For details on the difference between old and new models, refer to this XHDATA document.)

Downgrade?

More recently (2023?) the internal circuit of the of the radio was radically changed and users are reporting that the new version isn’t as loud. This version can be identified by rubber feet on the bottom and a USB-C charging connector (the prior version has a USB Micro). Others are speculating about poorer performance. I’ll post an update when I know more. Mine is this latest version. You can read more about the update on the Ultralight User Group.

Operation

I compared the XHDATA D-808 to my other $70+ radios: Tecsun PL-660, Tecsun PL-330, Sangean ATS-405, and Eton Executive Elite. Every one of them had the volume control on the lower right side of the radio except the XHDATA that has a fine tuning control there: drives me nuts trying to compare radios by turning down the volume on one and up on the other.

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Radio of the week: Sangean ATS-405

Posted on March 10, 2023 by Kevin

I like the Sangean ATS-405, but it tries my patience.

Sangean ATS-405 (Amazon.com product photo)

It’s an older model (it came out in 2015), but I picked it because it has some options not usually found on other radios: the ability to set the squelch level and options for tuning mute and soft mute. These have proven unimportant, but other features have come to the front. It also has an automatic gain control (AGC) setting, an advanced feature valuable in receiving some signals that are rapidly changing in strength.

Likes

One strong feature of the ATS-405 is the display. It is bright and easy to read in the dark (with the display light) as well as in full sun. A setting allows the display light to be always on, off or delayed off (10 or 20 seconds). There is also a dedicated light switch on the top of the radio. The information on the display is just what you need, and in particular it tells you the setting of the Local/DX switch (so you don’t accidentally have it set to Local). The bandwidth setting is there along with the signal strength. A quick button press switches to the clock display.

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Mesqool CR1015 — a radio you perhaps have not seen

Posted on March 7, 2023 by Kevin

I bought my Mesqool CR1015 (or CR1015WB) from Amazon back in April of 2022 as part of a bundle with a larger weather radio. In the bundle, it only cost $9.11, so what the heck? The original version of the radio is no longer available, but an updated version with rechargeable batteries is now offered on Amazon for a higher price.

While it has some limitations, it’s not junk, and today I want to talk a little about it.

Mesqool CR1015WB (Amazon product photo)

It’s an MW/FM/SW/Weather band radio with weather alerts. It has a belt clip, an earphone jack, a sleep timer and an 8-page instruction sheet. Shortwave coverage is 2.3 – 23 MHz, MW is 520-1710 kHz (10 kHz step) and FM is 87.5 – 108 MHz. It runs on 3 AAA batteries, with no external power supply provision. It has a key lock switch and an emergency SOS siren with a tiny red LED flashing light. The dimensions are approximately 4.5 x 2.6 x 1 inches (116 x 68 x 26 mm). The antenna extends 11 inches. I have seen pictures of a yellow version.

The major drawback to the radio is tuning; there is no easy way to get from here to there, especially on shortwave. The operator changes frequency by way of an up or down button. A long press of one of those buttons does a scan for the next active frequency and stops on it. Scanning the entire shortwave band takes 30 minutes. Ouch! If you want to go to a particular frequency, you can choose the closest direction from where you are and get there in a maximum of 15 minutes.

The radio received 3 daytime MW stations in this very weak signal area, better than some of my inexpensive radios that only get 1 station. Several get 4-5, my Tecsun PL-660 gets 12 and my vintage Panasonic RF-085 gets 20. What is unusual is that the radio appears to have the ferrite antenna aligned with the side of the radio, not the top, so to receive MW stations, the radio has to be placed on its side.

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Tecsun R-9700DX Radio Compared

Posted on March 6, 2023 by Kevin

I’ve hesitated to talk about the Tecsun R-9700DX radio much because while other reviewers like it, I was disappointed, and I didn’t want to bad mouth a radio unfairly. In this article, I’ll also refer also to my vintage Panasonic RF-085 receiver that I bought around 1985.

Panasonic RF-085 radio (left) and Tecsun R-9700DX (right)

I’ve been listening to shortwave radio for a very long time, and I have owned over 100 radios. What I expected from the R-9700DX was a good example of where analog technology had reached in the 21th century. I expected to be impressed but I wasn’t.

Let’s start with sensitivity specifications. Here are the values for two radios:

BandTecsun R-9700DXPanasonic RF-085
MW< 1 mV/m200 µV/m for 50 mW Output
FM< 10 µV 3 µV for 50 mW Output
SW110 µV for 50 mW Output
SW28 µV for 50 mW Output
SW35 µV for 50 mW Output
SW< 30 µV
Radio sensitivity specifications

That doesn’t help much because the Tecsun doesn’t specify a standard, and the Panasonic uses an uncommon one. I’ll assume the Tecsun is using S / N = 26dB, something quoted by Tecsun for other radios, and if so, the R-9700DX lags behind Tecsun’s DSP-based radios like the PL-330 and its digital display analog radios like the PL-660, both with 20 µV on SW and 3 µV on FM. MW is the same 1 mV. My personal observation is that the R-9700DX isn’t particularly sensitive. I get 7 MW daytime stations (weak signal area) on the R-9700DX, 12 on my Tecsun PL-660 and 20 on the Panasonic (that blows everything else away on MW). I mistakenly thought that a big heavy radio would have a big ferrite antenna and have good MW reception, but it really doesn’t. Shortwave performance was mediocre too.

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HanRongDa HRD-701 — Many Features, tiny package

Posted on February 26, 2023 by Kevin
HanRongDa HRD-701

As one can see from the photograph, the HRD-701 is one of the smallest shortwave radios on the market, but its designers packed in a world of features underneath that small exterior sporting just 7 buttons, a switch and two knobs. It comes with a battery, wrist strap, manual, 10 ft. clip-on external antenna, and waterproof carrying pouch.

Here are some of the features:

  • MW/FM/SW/Weather radio
  • Weather alerts
  • Alarm clock / Sleep timer
  • Automatic station scanning
  • Tuning indicator light
  • Station Memories
  • Music player from TF/Micro SD card (256 GB)
  • Key lock
  • Bluetooth speaker
  • Rechargeable battery (BL-5C) with USB-C charging
  • Region settings for FM range and MW channel width
  • Graphic equalization display and settings playing music files
  • SW: 4.75 – 21.85 MHz, one continuous band

Of course, a small size introduces some problems, one being that the display electronics can generate radio noise noticeable on some frequencies. It also means that the whip antenna is relatively short, about 11″ (28 cm). The one feature that I do miss is an earphone jack. The one feature I can do without is the Soldier/Army insignias on the sides of the unit. The case labeling states: “PLL WORLD BAND RADIO BLUETOOH MUSIC_PLAYER,” but I sincerely doubt that this radio is PLL; it’s DSP.

This video shows an example of the internal noise on one particular channel (the video opens with the HanRongDa, not the Kaito).

I did a scan of the MW band in daytime here in a very weak signal area. I got 4 stations clearly. This is average performance. The poorest performers only get 1 station, and the best get 20. Shortwave is average also, certainly no DX machine. I get my local NOAA weather station perfectly, but it is not that far away. FM is always good on these DSP radios.

The speaker is a 3W according to the manual, and it proved remarkably loud and of good quality, surprisingly good for something this small.

One unusual feature is the ability to tune the radio by display digit. When you turn the tuning knob, you will see a tiny caret symbol appear inside and near the top of the right-most digit. The tuning wheel increments on that digit. If you press the MOD button, the caret will shift one digit to the left and then the tuning wheel controls that digit. It’s a clever way to do near direct entry of a station frequency. This allows relatively fast tuning despite the lack a frequency entry keypad.

Overall this a fun little radio. It’s feature rich and well-designed.

It costs $38.99 USD currently on Amazon, and around $28 at AliExpress (including shipping to the US).

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