Category Archives: Scanners

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:

Listen to an upcoming ARISS contact with your scanner or HT

On April 18, consider setting your scanner or handheld VHF radio to 145.80 MHz around 15:57 UTC; you may be able to hear the downlink from the International Space Station. The Amateur Radio on the International Space Station (ARISS) contact will be between between NA1SS (on the ISS) and KD2IFR at a school in Central Islip, NY.

As long as you’re within the ISS’ signal footprint (which is rather large) you should be able to easily hear NA1SS’ side of the conversation. I’ve listened to the downlink in the past using an Icom ID-51a and the super compact Yaesu VX-3R:

Click here to view on YouTube.

Click here to view on YouTube.

The frequency of the downlink will be 145.80 MHz. As the ISS climbs above your horizon, because of doppler-shift, listen on 145.805, then move to 145.80 as the ISS approaches zenith and finally move to 145.795 MHz as the ISS drops toward the other horizon. As we’ve mentioned in past posts, you’ll know when to switch frequency when the audio gets bad.

ARISS contacts happen quite frequently–I’m posting this notice because I’ve noted it in my own calendar. Check out the ARISS “Upcoming Contacts” page where future ARISS QSOs are listed. This is a great opportunity to show kids of all ages what you can hear with a modest radio!

Check out a news article about this event via the Southgate ARC:

Upcoming ARISS contact with Central Islip Union Free School District, Central Islip, NY

An International Space Station school contact has been planned with participants at Central Islip Union Free School District, Central Islip, NY on 18 April.

The event is scheduled to begin at approximately 15:57 UTC. The duration of the contact is approximately 9 minutes and 30 seconds.

The contact will be direct between NA1SS and KD2IFR. The contact should be audible over the state of New York and adjacent areas. Interested parties are invited to listen in on the 145.80 MHz downlink. The contact is expected to be conducted in English.

Welcome to the Central Islip Union Free School District – Home of the Musketeers and a proud Suffolk County, New York school system, where approximately 8,000 students in grades Pre-Kindergarten through 12 receive their formal education. Our School District’s motto is Children Our Future ~ Diversity Our Strength. The Central Islip Union Free School District is comprised of eight schools: one district-wide early childhood center, four elementary schools, two middle schools and a high school.

The Hamlet of Central Islip is a vibrant, culturally-diverse community. A suburban community with urban demographics. We are a positive and progressive school district whose teachers are dedicated to helping students achieve their maximum potential and to develop academically and socially. Our district offers an array of afterschool activities including sports, music, theatre arts and much more.

Participants will ask as many of the following questions as time allows:

1. What are the challenges of spending so many months constantly around the same people?
2. What is the best way to describe the feeling of zero gravity?
3. Have you experienced anything unexpected while in space that could not be explained?
4. Have you experienced any significant changes, either physically or emotionally, since being in space?
5. What type of robots do you use on the ISS and how are they helpful?

6. What is your advice for young people who want to become involved in programs at NASA?
7. What is the biggest challenge about being on a long duration space mission?
8. How does digestion in microgravity compare to digestion on Earth?
9. Have you experienced anything in space that has made you change your perspective on life?
10. Are there any plants aboard the ISS and if so, what’s different about how they meet their daily requirements?

11. What are the long term effects of reduced leg muscle use in long duration space travel?
12. Is your circadian rhythm affected by multiple sunrises and sunsets each 24 hour period, perhaps making it difficult to sleep for long periods of time?
13. Can you describe the types of training that prepared you for this mission?
14. Can you catch a cold on the Space Station?

15. Do the properties of light appear to be different in space?
16. Are there differences in how your body responds to physical exertion while in microgravity?
17. Would it be possible to transmit a mechanical wave on a rope onboard the space station or outside the station?
18. What are the hardest tasks to perform in space that are routine on Earth?
19. Could you blow a bigger than normal gum bubble in space?
20. Are there precautions that you take BEFORE going into space that can help to prevent bone weakness when you return?

PLEASE CHECK THE FOLLOWING FOR MORE INFORMATION ON ARISS UPDATES:

Visit ARISS on Facebook. We can be found at Amateur Radio on the International Space Station (ARISS).
To receive our Twitter updates, follow @ARISS_status

Next planned event(s):
1. King’s High School, Warwick, UK, direct via GB4KHS
The ISS callsign is presently scheduled to be OR4ISS
The scheduled astronaut is Ricky Arnold KE5DAU
Contact is a go for: Thu 2018-04-19 12:05 UTC

2. Russian school TBD
The ISS callsign is presently scheduled to be RS?ISS
The scheduled astronaut is Alexander Skvortsov
Contact is a go for Tue 2018-04-24 11:05 UTC

3. Russian school TBD
The ISS callsign is presently scheduled to be RS?ISS
The scheduled astronaut is Alexander Skvortsov
Contact is a go for 2018-04-25 08:35 UTC

About ARISS:

Amateur Radio on the International Space Station (ARISS) is a cooperative venture of international amateur radio societies and the space agencies that support the International Space Station (ISS). In the United States, sponsors are the Radio Amateur Satellite Corporation (AMSAT), the American Radio Relay League (ARRL), the Center for the Advancement of Science in Space (CASIS) and National Aeronautics and Space Administration (NASA).

The primary goal of ARISS is to promote exploration of science, technology, engineering, and mathematics (STEM) topics by organizing scheduled contacts via amateur radio between crew members aboard the ISS and students in classrooms or informal education venues. With the help of experienced amateur radio volunteers, ISS crews speak directly with large audiences in a variety of public forums. Before and during these radio contacts, students, teachers, parents, and communities learn about space, space technologies, and amateur radio.

For more information, see www.ariss.orgwww.amsat.org, and www.arrl.org.

Thank you & 73,

David – AA4KN

Dave’s review of the AOR AR-DV1 Digital Voice Receiver

Many thanks to SWLing Post contributor, Dave Zantow (N9EWO), who has recently posted his review of the AOR AR-DV1 digital voice receiver.

As with many of Dave’s reviews, this evaluation takes a close look at HF and mediumwave performance which isn’t the AR-DV1’s strong suit. Dave notes:

“[Though] not what the receiver was designed for, RF performance on MW / HF bands (and the terrible audio quality) are mediocre at best.”

Click here to read Dave’s review.

Thanks, Dave! Your review reflects comments I’ve received from some Post readers who’ve purchased the AR-DV1 as well. Many were particularly upset with the audio quality. Of course, the AR-DV1 is marketed as a digital voice receiver, thus audio likely favors “narrow” voice audio.

The Uniden SDS100 True I/Q Scanner

Many thanks to SWLing Post contributor, Dave Zantow (N9EWO), who shares information about the new flagship handheld scanner from Uniden: the SDS100.

Here are the details from Uniden’s press release:

SDS100 Coming Soon

Uniden creates another first with the SDS100 True I/Q Scanner, the first scanner to incorporate Software Defined Radio technology to provide incredible digital performance in even the most challenging RF environments. The SDS100’s digital performance is better than any other scanner in both simulcast and weak-signal environments.

The SDS100 is also the first scanner that allows you to decide what to display, where, and in what color. Custom fields put the information important to you right where you need it.

And, one more first, the SDS100 meets JIS4 (IPX4) standards for water resistance.

Slated for release in 2nd Quarter, 2018, the SDS100 carries an MSRP of $699*.

Of course, the SDS100 also includes all the advanced features you’ve come to expect from a Uniden scanner, including:

  • Customizable Color Display
  • Trunktracker X
  • APCO P25 Phase I and II
  • Motorola, EDACS, and LTR Trunking
  • MotoTRBO Capacity + and Connect +**
  • DMR Tier III**
  • Hytera XPT**
  • Single-Channel DMR**
  • NXDN 4800 and 9600**
  • EDACS ProVoice**
  • Location-Based Scanning
  • USA/Canada Radio Database
  • ZIP Code Selection for Easy Setup
  • Close Call™ RF Capture with Do Not Disturb
  • 8 GB microSD
  • Soft Keys for Intellegent UI
  • Recording, Playback, and Replay
  • Temporary Avoid
  • Fire Tone-Out Alert
  • System Analysis and Discovery
  • CTCSS/DCS/NAC/RAN/Color Code Decoding
  • S.A.M.E. Weather Alert
  • Enhanced Dynamic Memory
  • Preemptive Trunking Priority
  • Fully Customizable Scanning with your own Favorites Lists
  • Backlit Keypad
  • Channel Volume Offset
  • PC Programming and Control
  • USB Connectivity and Charging
  • Weekly Database Updates
  • Free Sentinel Software keeps the SDS100 database and memory up to date
  • Up to 8 Hours Operation on included LiIon Battery
  • Frequency Coverage:
    • 25-512 MHz
    • 758-824 MHz
    • 849-869 MHz
    • 894-960 MHz
    • 1240-1300 MHz

Dave shares this Uniden SDS100 Intro Video:

Click here to view on YouTube.

Spec Sheet

Click here to download the Uniden SDS100 spec sheet (PDF).

Beta Owner’s Manual

Click here to download the Beta version of the Owner’s Manual (PDF).

Dave notes:

“[The SDS100] actually is bit smaller than the 436 and if the performance is like they say (see attached picture), then this could be a very exciting scanner indeed!!”

Yes indeed!  I have the Uniden BCD436HP and love it.  It’s such a simple handheld scanner to operate and there’s no real need to “program” it as it will automatically load relevant frequencies based on GPS coordinates or a postal/zip code. This looks like a significant upgrade and I love the fact it’s water resistant.  Of course, MSRP is projected to be $699 US–not a small investment.

Thanks for the tip and all of the links, Dave!

Mario spots a rare J.I.L. Communications Receiver SX-400 on eBay

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

Hope you are doing well. Spotted this J.I.L. receiver on eBay, never heard of this unit before.

Click here to view on eBay.

Thanks for the tip, Mario! This is a new one for me as well–what an interesting stack-able set of up/down converters. RigPix has a few more details.

Post readers: Can anyone comment about this until or its performance on the HF bands?