27.195 MHz Nonstop Data Stream + MFSK Bursts [RCRS] Via W3HFU SDR 3 Feb 2025

[R4002]

Noting this basically every time the band is open.  Possibly out of South or Central America.

27.195 MHz data bursts going nonstop, also Mexican taxi cab dispatcher on 27.195 MHz AM in the background.  Lots of activity today.


Center frequency roughly 200 Hz off-frequency, 27.194.8 MHz 27194.8 kHz or so.  Not to bad at all and well within the FCC Part 95 Subpart C RCRS regulations for frequency accuracy.  +/- 1.35 kHz from center frequencies 26.995 MHz, 27.045 MHz, 27.095 MHz, 27.145 MHz, 27.195 MHz and 27.255 MHz.  If the power output is 2.5 watts or less the frequency accuracy requirement is even more "loose" and becomes +/- 2.7 kHz from the center frequencies.  Bandwidth limited at 8 kHz, so it is well within that as well.

27192.6 kHz - 27197.3 kHz - so we're looking at 4.7 kHz, 4.8 kHz bandwidth.  Maybe call it 5 kHz bandwidth

[Robot Matrix]

I've heard the data bursts on 195 as well as below the CB band. Made a post about the 195 signal on January 20, 2025, 2358 UTC. Curious as to what it is?!

Oh.. and I DID remember hearing a voice transmission during and in between... that was a Mexican cab service???

[ThaDood]

That's not all that's there. A friend of mine alerted me to a Speak-Repeater on 27.195MHz AM. It's one of those devices, that connects any transceiver's Mic & Audio OUT, records up to 30sec of audio, and re-transmits it back. Radio Shack sold one and so did MFJ. So, not far fetched that someone would put one to a CB.

[Robot Matrix]

Oddly enough,  I DID hear some chatter in English on that frequency today, but I only caught the tail end. It was in LSB.

[Robot Matrix]

That's not all that's there. A friend of mine alerted me to a Speak-Repeater on 27.195MHz AM. It's one of those devices, that connects any transceiver's Mic & Audio OUT, records up to 30sec of audio, and re-transmits it back. Radio Shack sold one and so did MFJ. So, not far fetched that someone would put one to a CB.

Didn't see this till now.  No idea how I skipped over this.  Yeah,  that's a simplex repeater. That technology is still around with some of the Chinese VHF/UHF radios. 

[R4002]

Simplex repeaters are extremely popular on 11m CB in Europe and Russia.  No doubt there are some in the U.S.A. as well, especially since FM mode is legal on 11m CB now.  I also know of at least one AM mode simplex repeater on CB channel 20 - 27.205 MHz AM in New Zealand - see video link here:

https://www.youtube.com/watch?v=6u9mQpy7Mhw

^ 27.205Mhz AM (ch20) New Zealand Simplex Repeater heard in Australia. 27/3/23 - that's March 27th, 2023. 

There are several linked networks of them, especially in Germany, Austria, Czech Republic and other locations.  Many of the linked networks require CTCSS tones, which CB gear is slowly starting to include as standard equipment.  There are traditional duplex repeaters in Germany, I know of one on 26.565 MHz FM input / 27.405 MHz FM output and another on 26.575 MHz FM / 27.395 MHz FM.  There are no doubt others.    The linked systems are called "hotspots" or "gateways"

See link here:

https://www.hfunderground.com/wiki/index.php/CB#CB_Hotspot_Internet_Gateways_Remote_Stations_List

Video of the 27.405 MHz FM output / 26.565 MHz FM input repeater in Germany:

https://www.youtube.com/watch?v=XCA6mkc7ln0

Video of the 27.395 MHz FM output / 26.575 MHz FM input repeater in Germany:

https://www.youtube.com/watch?v=8la5H4dVlmE

Do a Google search for "27.205 MHz FM repeater" - there is one in Sweden that has a bunch of pre-recorded audio clips that it will play if you transmit various DTMF tones into the receiver.  Unfortunately the Russian FM CB channel 20 (frequency: 27.200 MHz FM) often gets into the passband of the 27.205 MHz and makes the 27.205 MHz FM simplex repeater re-transmit the adjacent channel QRM as an actual transmission. 

See link for a (partial) list of the simplex repeaters and duplex repeaters here:

https://www.hfunderground.com/wiki/index.php/CB#CB_Repeater_Listing


Since you have find a simplex repeater controller for pretty cheap now, look up the Radio-Tone RT-SRC1 simplex repeater controller and the SureCom SR-112 simplex repeater controller...the SR-112 is available on Amazon and eBay for the $50-$60 ballpark and come with the standard "Kenwood" audio connector used on Baofeng UV-5R and similar Chinese radios. 

However, there are now CB rigs on the market that come with that same audio connector as the Baofeng UV-5R and all the other Chinese HTs.   Examples include the PNI Escort HP 82 handheld as well as the mobile radios PNI HP 9500 and PNI HP 8001 - both of which are very small form factor radios with lots of capability. 

The HP 8001 is an inexpensive radio the same size as the Uniden PRO510XL / PRO520XL but with AM/FM capability, full channel capability (multi-norm, 80 channel German CB band 26.565 MHz - 27.405 MHz), the US/EU 40 channel band 26.965 MHz - 27.405 MHz AM/FM, the UK FM CB band, plus the full export mode or "RU mode" 25.615 MHz - 30.105 MHz and 25.610 MHz - 30.100 MHz.   

The PNI HP 8001 is available for (roughly) $80, so repeater controller + radio can be had for under $150 or so.  Link to the HP 8001 https://www.bellscb.com/products/cbradios/PNI/PNI_Escort_HP-8001L.htm

I know there is a newer President CB radio - President Washington 12m/11m/10m radio that recently came to market that includes a simplex repeater option (advertised as an "automatic relay" function) as standard built-in equipment as part of the radio from the factory.

https://www.bellscb.com/products/tenmeter/President/Washington.htm

In other words, one could set up a simplex repeater on 11m CB for minimal cost.

-Simplex repeater controller (SureCom SR-112 with 2-pin Kenwood / Baofeng style audio connector)   $60

-PNI HP 8001 CB radio with the same 2-pin audio connector right on the front panel  $80

-DC power supply for the radio:  $30 or less

-Base antenna free to a lot of $$$ but basic 1/2 wave or 1/4 wave vertical would work just fine

-Coax cable

Total cost, depending on the antenna you use, how much coax you have laying around and so on...just under $200 or so to $300+

Still, big picture...that's not bad, not bad at all.  There are also crossband repeater controllers available for the same price range as a SR-112 or a Radio-Tone RT-SRC1+ simplex repeater controller that allow you to set up a VHF or UHF radio and crossband 11m and VHF (say, MURS) or UHF (say, GMRS/FRS) with relative ease. 

That, and adapter cables are available to simply build your own mic connector to connect the repeater controller to the radio and connect the radio's audio output (external speaker connection, 3.5mm / 1/8" mono plug) to the repeater controller, with a little bit of knowledge about a specific radios' mic pinout...it can be done with any radio.

There are several of the PNI brand radios that have the Kenwood style 2-pin TX audio in/RX audio out connector on the front panel, they are a little bit more expensive than the HP8001. 

-PNI HP 9500 CB radio with the same 2-pin audio connector right on the front panel  $100
-PNI HP 8500 CB radio with the same 2-pin audio connector right on the front panel  $130