Category Archives: FM

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:

RootIO and a new community radio initiative in Uganda


(Source: Global Voices via Mike Hansgen)

How RootIO Broadcasts Radio in Uganda Using a Bucket

The open-source toolkit allows users to broadcast using just a smartphone and a transmitter

Radio is still and continues to be a powerful medium across most of the African continent. Not only is radio used to share community information but it is cheap and very accessible. In Uganda, a mixing of radio’s power with new mobile and internet technologies has created a cheap and powerful open-source toolkit that allows communities to create their own micro-radio stations. All one needs is an inexpensive smartphone and a transmitter and a community that will share, promote and collaborate on dynamic content.

[…]They have no studio and all the radio shows are done using the host’s smartphone.

How does this work? Users can purchase most of the materials at local markets. A small transmitter is built into a waterproof bucket with a fan, a charge-controller and a smartphone, which is connected to an antenna and a solar panel.

The radio stations are really small and can serve a village or a couple of villages reaching to 10,000 listeners. The content produced by the radio hosts lives in the cloud so stations are able to share content with other stations.[…]

Click here to read the full article at Global Voices.

Note that we first published a post about RootIO five years ago. Very happy to see it’s now in use!

The FCC’s mission to shut down pirate radio

Recently, there have been numerous articles regarding FCC Chairman Ajit Pai’s efforts to increase pirate radio enforcement. This article in The Outline is a worthy read and features our good friend David Goren prominently:

The FCC wants pirate radio stations off the air

Immigrant communities rely on these unlicensed broadcasts to stay connected to their roots. Now they could lose the signal.

On any given night, David Goren can tune into more than 30 underground radio stations from his apartment in Flatbush, Brooklyn. “About a dozen of them broadcast in Creole, to the Haitian community,” Goren, a local journalist and producer who researches the city’s pirate stations, told The Outline. “A lot of the stations will air news from home.” In addition to news and politics updates, Goren said, these stations feature Caribbean music that doesn’t get airtime on mainstream stations, advertisements for local businesses, and occasional call-in sessions with immigration attorneys.

For some immigrant communities across the country, these underground radio stations are an easy way of staying connected to one’s roots. In New York City, there may be more unlicensed broadcasters than licensed ones. Some of these clandestine broadcasters are small enterprises, while others are full-fledged stations that run advertisements and generate revenue. All of them run the risk of being fined — or in some states, including New York, New Jersey, and Florida, having their operators imprisoned — if they’re caught by the Federal Communications Commission.

[…]A map of enforcement actions on the FCC’s website illustrates the crackdown. The FCC has undertaken 306 pirate investigations since Pai took office in January 2017. The majority of these actions — 210, according to a press release issued by the agency on Wednesday — were Notices of Unauthorized Operations, warnings from the FCC telling the unlicensed stations to immediately shut down or risk fines and prison time. The release also notes that the FCC “took more than twice as many actions against pirate broadcasters” in 2017 than it did the previous year. (For the first time since its inception, the agency said, it has begun holding property owners liable for “supporting this illegal activity on their property.”)[…]

Click here to read the full article on The Outline.

Blackloud SounDot AF1 earphones offer FM reception for iPhones

Many thanks to SWLing Post contributor, Richard Langley, who shares this article from Radio World. Here’s an excerpt:

Headsets Deliver FM to Mobile Devices, No Chip or Internet Required

[The BLACKLOUD SOUNDOT AF1] headsets are nothing like the ones you might remember from your first Sony Walkman. According to information provided by Blackloud, SounDots feature patented psychoacoustic technology, a six-band customizable graphic equalizer, 3D stereo effect, dual dynamic driver design, inline microphone, and a control box with a volume up (+), volume down (–) and multifunction (pause/play) button. This multifunction button enables many actions depending on the app that is running, including: answer/hang up a phone/video call, start/stop recording or playback using most any audio/video/camera app, enable/disable/seek up/down the FM tuner, and lastly, activate Siri or Google Assistant.[…]

Click here to read the full article at Radio World.

Richard notes that we’ve posted articles in the past focusing on the fact that iPhones (and a number of Android phone models) do not have or allow user access to a built-in FM reception chip.

Richard sees the new Blackloud SounDot AF1 earphones as an elegant work-around and has pre-ordered a set. If these earphones live up to their specs, they should sound fantastic.

Richard, I hope you’ll post a review after you put them into service! Thanks for the tip!

Click here to view the SOUNDOT AF1 ordering page.

“Threatened radio shut down” in Germany

UPDATE:  Many thanks to Mike Barraclough who notes that a report today is that this has been averted. Click here to read.

(Source: Southgate ARC)

Germany – up to 10 million people could be hit by threatened radio shut down

The airwaves across many parts of Germany could fall silent next week due to a financial dispute between radio stations and an FM broadcasting provider.

The company Media Broadcast announced on Friday that it would cut off FM broadcasters for several radio stations if they did not immediately fulfil certain payment demands.

“Up to 10 million radio listeners could be affected by their FM broadcaster being cut off from Wednesday onwards,” company head Wolfgang Breuer told Die Welt.

Major public service broadcasters such as MDR, NDR and Deutschlandfunk are among those who could be cut off, the newspaper reported.

The dispute began when Media Broadcast, formerly a subsidiary of Deutsche Telekom, decided to move focus away from FM radio and onto digital platforms last year. The shift meant that broadcasting antennae across Germany, for which Media Broadcast had previously been responsible, were sold to private investors.

Broadcasters and their network operators were then left furious when many of the new owners raised prices for the use of their antennae, leading to a stalemate in business negotiations.

Hessian broadcaster FFH told dpa that a 50 percent rise in the cost of antennae use had left them with a “massive problem”.

In order to break the stalemate, Media Broadcast recently agreed to continue operating all antennae until the end of June, so as to provide more time for negotiations. Yet such an arrangement would still require the stations to contract the company during that period.

Media Broadcast now claims that around 75 percent of stations have not done this, and has threatened to cut these stations off if they do not officially contract the company by Monday.

Though digital and online streaming radio will still be available, the mass cut-off of FM radio broadcasts would affect a huge proportion of the population. According to Bild, around 92.7 percent of Germans said they still preferred listening to radio on an analogue device in a poll last year.

Up to 10 million people could be hit by threatened radio shut down

https://www.thelocal.de/20180406/up-to-10-million-people-could-be-hit-by-threatened-radio-shut-down