Category Archives: Accessories

Guest Post: Review of the TYT SF-401 Plus Frequency Counter/Tone Meter

Many thanks to SWLing Post contributor, Mario Filippi (N2HUN), for sharing the following guest post:

TYT Frequency Counter/Tone Meter Review

by Mario Filippi (N2HUN)
All photos courtesy of author

Most hobbyists own some type of transceiver whether it is a handheld, mobile, or base station. Some examples are amateur radio HF/VHF/UHF transceivers, Citizen’s Band radios, FRS (Family Radio Service) and GMRS (General Mobile Radio Service) handhelds.

A useful tool for the shack or the field is a frequency counter/tone meter since it can measure frequencies and analog/digital tones from transmitters/transceivers. At times ascertaining that a UUT (Unit Under Test) such as a 2 meter handheld is transmitting accurately may be indicated due to problems communicating with other stations. In addition, if the UUT transmits a sub-audible tone (either analog or digital) to access a repeater, a frequency counter/tone meter can detect the presence and verify accuracy of the CTCSS/digital tone.

Author’s TYT SF-401Plus, includes instructions, antenna, rechargeable battery and charger/cable. Covers 27 MHz – 3 GHz

Frequency/tone meters can be purchased for less than twenty US dollars but normally do not include a rechargeable battery and BNC connector for attaching an external antenna. Having had experience with these types, the time finally came for an upgrade.

After shopping around a decision was made to purchase the Tytera TYT SF-401 Plus. This model includes an instruction sheet, antenna, internal rechargeable battery, USB charger and cable. It represents a significant improvement over my previous, inexpensive meter, as the TYT has a BNC connector to attach a larger antenna and has four control buttons on the front panel. It also has, via a system menu, options to adjust the frequency/tone offset, dimmer levels, three or four decimal display and auto power off. All these valuable features warrant a higher cost, which was about $50, but well worth it. This price fits the budget of most hobbyists. However, higher end frequency/tone meters are available and cost several hundred dollars for those requiring that level of quality.

Out of the box the TYT SF-401 Plus, when checked against an IFR FM/AM-500A communications service monitor, was right on the money as far as accuracy. Note that the IFR-500A was calibrated against a high precision internal 10 MHz crystal in an “oven” and this is my gold standard reference for frequency accuracy in my shack.

TYT accuracy checked against an IFR FM/AM-500A communications service monitor transmitting a 146.52 MHz/131.8 Hz tone. Note frequency readout to four decimal places.

Now, it was time to check typical radios around the shack using the TYT. The first radio tested for frequency accuracy was a BTECH GMRS-V1 HT which I use to communicate with the home QTH while running errands around town. See photo for results. The BTECH and TYT agreed perfectly. Note that the TYT’s display includes a battery status indicator on top left and a timer use indicator, which resets every time the TYT is turned on. If you are going to measure digital signals (not included in this review) there is an option in the Setup Menu for that. With the BTECH handheld running 2 watts the TYT could detect its’ frequency at roughly four feet away.

Confirming BTECH transmit frequency against the TYT. Output is 2 watts. TYT multicolor display is super.

For VHF/UHF operating, especially when afield with other hams or groups such as CERT (Community Emergency Response Teams), problems can ensue if one does not have the correct frequency or tone programmed, so having the TYT in your shirt pocket to confirm these parameters when trouble occurs can be a quick way to get to the problem. See photo of an Icom IC-2300H 2 meter transceiver checked against the TYT for proper offset and tone. The Icom was putting out 65 watts and a repeater with an offset of -1.3 MHz and 88.5 Hz tone was checked.

TYT confirming unusual offset (-1.3 MHz) and tone for a repeater. Icom IC-2300H was at high (65W) setting and connected to an outdoor discone antenna.

According to the instructions included with the TYT SF-401 Plus, the operating range is from 27 MHz – 3000 MHz with a note stating “27 MHz – 100 MHz it can not be guaranteed and the corresponding normal emission appliance” which I interpret as accuracy is not guaranteed in this frequency range. Well, I checked the TYT against the IFR FM/AM-500A service monitor transmitting an AM signal on CB Channel 19, 27.185 MHz, and the TYT measured it exactly. One other important note is that according to the instructions, the tone decoder operates in the 136 MHz – 174 MHz and 400 MHz – 520 MHz frequency range. So that may limit its use in certain areas of the spectrum. One other item if interest is that the TYT has a 10 dB attenuator when dealing with high power signals.

All in all, I’m very happy with this purchase, and find the TYT SF-401 Plus useful for “first pass” troubleshooting and helpful when aligning older rigs which due to age are off frequency /tone. It definitely has a use in this shack.

Wow–what a bargain tool for the radio shack! Thank you for sharing your review, Mario.  Once again, however, you have tempted me with a purchase!  I remember when frequency counters would set you back a couple hundred bucks–it’s insane to think that you can grab one for $40-50 US shipped.

SF-401 Plus Retailers:

Note that the TYT SF 401 Plus is also marketed as the Surecom SF401 Plus:

The Professor reviews the RFA200 external ferrite antenna

Many thanks to SWLing Post contributor, The Professor, who shares the following review of the RFA200 external ferrite antenna:

The Tecsun R-9012 and RFA200 MW antenna (Photo credit: The Professor)

A Quick Review of the RFA200

The Professor

I’ve considered saying something here about RFA200, as I bought one of these not long after its existence was announced on this blog a few months ago, but I’ve been hesitating because I didn’t have much good to say about it. A couple of times I’ve placed it up snug up against the the top of the two Tecsun sets I have handy (the PL-310ET and the PL-880) and found that despite a lot of knob turning it had little or no effect on improving signal on medium wave stations. I was not impressed.

But I guess I’ve kind of changed my mind on that. And oh yeah, I bought another radio. It’s funny how you can talk yourself into things when you’re talking someone else into something. But after I had mentioned to a reader here the other day that the very inexpensive Tecsun R-9012 was a worthy analog DX portable, I decided to drop twenty and pick one up for myself. After all, it was about the same price as a fancy Brooklyn hamburger. It arrived a couple days ago.

So, I have been playing with it a bit over the last few days. It’s as good as the other ones I’ve had which are the same basic radio (I’d mentioned that the bandswitch slider broke in a couple of mine). It’s single conversion. The bandwidth is a little wide, but it’s a very sensitive and simple analog set.

Yesterday I was going through the AM band and remembered that ferrite from Greece, and I pulled it out recalling that in my experience some radios are more susceptible to reception improvements using passive loops than others. Maybe this ferrite bar might be similar. And sure enough, the antenna made a notable difference this time. By placing it up against the R-9012 and tuning the thing I could certainly increase signal a bit. And I could even see it in the slight brightening or steadiness of the tuning light.

So, not a total waste money after all. I would emphasize that the difference in reception doesn’t seem to be as dramatic or sustaining as you might hear with a tunable loop antenna next to your radio. But it’s not junk either. Then again, for fifty dollars shipped it is a little pricey. Twice as much as a Tecsun tunable loop antenna, and two and half times more expensive than the R-9012 itself.

I found the best way to use this antenna is to tune the radio separately first and when you find a weaker signal you want to improve physically go ahead and rotate the radio until the signal is strongest and THEN put the antenna along the top of the radio and adjust the tuning knob on the antenna. Focus in on strengthening the signal you actually hear, going back and forth until it gets strongest. If you seem to be pulling up other stations it’s because the antenna adjustment will bring in adjacent stronger stations if you move it too far either way.

I’m surely not able to pin down the science involved in exactly how these things work, but perhaps somebody can chime in on this. I’m wondering if analog radio tuning in particular is better suited to the use of these tunable passive antennas, as opposed to PLL and DSP radios?

If you buy one of these be prepared to wait. At least mine took weeks to get here from Greece. And don’t expect miracles. But it seems rather well constructed, and will probably work with some radios. The seller has a 100% rating on eBay and has all sorts of interesting antennas for sale. I’m glad to see people succeeding in that business.

Many thanks, Prof, for sharing your fine review of the RFA200! Thanks for also mentioning the Tecsun R9012–I purchased one a couple years ago with the intention of reviewing it, then gave it to teenager who expressed interest in shortwave. I don’t think I actually put it on the air myself. I do enjoy simple old school analog radio–especially when making band scans. 

Click here to view the RFA200 antenna on eBay.

The new Raspberry Pi 3 B+ and a number of RPi projects

Last month, on “Pi Day” (March 14, 2018) an upgraded Raspberry Pi 3 B was announced on the Raspberry Pi website. The new $35 B+ sports a few performance enhancements over the original–most notably:

  • A 1.4GHz 64-bit quad-core ARM Cortex-A53 CPU
  • Dual-band 802.11ac wireless LAN and Bluetooth 4.2
  • Faster Ethernet (Gigabit Ethernet over USB 2.0)
  • Power-over-Ethernet support (with separate PoE HAT)
  • Improved PXE network and USB mass-storage booting
  • Improved thermal management

Here’s a short promo video posted with the announcement:

Click here view on YouTube.

I immediately navigated to my favorite Raspberry Pi source–AdaFruit–and requested a notification when the new units were available to purchase. A few weeks later, I got the notification and placed an order within minutes (you see, when the Pi 3 B was first released, I hesitated a day and had to wait a few weeks for the second shipment!).

I received my RPi 3 B+ a few days ago:

I immediately attempted to put this unit into service but learned that it requires the latest firmware which was only released a week or so ago. If you have have an RPi 3 B+, here’s where to fetch the latest firmware:

or if you want Raspbian:
and install on SD per instructions here: … /

After receiving this latest Pi, I quickly realized I’ve bought a number of Raspberry Pi models over the years and currently have them in service for a variety ofc projects.  Here’s a list of all of my current Pi-powered applications:

That’s a total of seven RPi projects that are in service at time of posting!

As I mentioned earlier, I try to buy most of my Pi equipment from the amazing AdaFruit retailer–I like supporting what they do even if I pay a small premium.

But AdaFruit seems to rarely have stock in some of my favorite Pi bundle packages. If I’m buying a Raspberry Pi for a new application, I look for a package with at least a case, a 2.5 amp power supply, a 32 or 64GB MicroSD card, and two heat sinks (though I’m not certain the B+ needs a heatsink). I tend to grab this one or this one from Amazon (affiliate links).

Post readers: Have you ever used a Raspberry Pi? If so, in what sort of applications? How many do you own?  Please comment!

The Lazy Susan: Mario’s mediumwave companion

Many thanks to SWLing Post contributor, Mario Filippi (N2HUN), who writes:

Grundig AN-200 Loop Antenna and Lzy SusanHere is a handy tip for those using small magnetic loops, like the Grundig AN-200. Using a simple Lazy Susan makes rotating the loop a lot easier as in the picture attached. It gives you a very smooth 360 degree rotation using a simple flip of a finger. Lazy Susans come in all sizes and luckily I had one already which fits the AN-200 perfectly.

This is a handy tip, indeed! In fact, I once spoke with a mediumwave DXer who told me that when he prepares for a DXpedition, he packs the Lazy Susan before he packs his portable’s batteries!

Lazy Susans are quite easy to find. Most “big box” retailers have them, has a massive inventory (affiliate link), IKEA and I’ve had incredible luck finding them at thrift stores for next to nothing! In fact, if you have a local thrift store with a large selection of kitchen accessories, you’ll likely find a Lazy Susan or two on the shelves.

Thank you for the tip, Mario!

The XHDATA D-808 and longwave: how to build an effective antenna

Many thanks to SWLing Post contributor, Mad Radio DXer, who writes:

I said I would share my results for attempting to receive LW signals on the XHDATA D-808, & if I can use a longwire to improve reception on this radio. This was after posting videos when I used around 50 metres of longwire connected to the D-808 for improved Medium Wave reception & to prove it works.

This first video shows that it is not possible for LW, no matter if I connect the 50 metres longwire to the 3.5mm input or the whip antenna. I also compare reception of the same station with the Degen DE1103 PLL using the 3.5mm input. The Degen DE1103 still had better reception even when I used the whip antenna extended at the very minimum when using the LW/MW external antenna trick. I know I should have used the internal ferrite antenna of the Degen compared to the D-808, but in any case I did try off camera & reception was about the same. So unfortunately the D-808 was never going to win this round.

However, there is a solution.

The answer? Build yourself a Long Wave induction antenna as shown in the second video [below]. I made one some time ago, as I grew frustrated at how poor the Tecsun radios were on this part of the band & that there were no LW induction antennas available to buy. I tried a signal on 207 kHz which is RÚV Rás 2 from Iceland. Either a radio with a very good internal antenna or a good external antenna is needed to receive this station at my QTH in southern England.

Placing the D-808 on the induction antenna resulted in a very pleasing result, which was it did get reception of Iceland on 207 kHz. So this shows that it is possible to DX on the LW bands with the D-808 with some “external help”.

For anyone interested making a LW induction antenna as shown above, here is a link to a video that has basic instructions & further results. It may be a very simple build & finish what I did, but for me the most important thing is that it works.

I hope my comments & videos will be a great help to all. Happy DXing.


Mad Radio DXer.

Excellent–your comments and videos are most welcome! There are quite a number of SWLing Post readers who are avid longwave DXers. I love the simplicity and efficacy of your longwave antenna–something anyone could build.  A clever upgrade to the affordable D-808. Thank you for sharing!