Booker Gliding Club
Wycombe Air Park
Marlow
Buckinghamshire
SL7 3DP

t; 01494 442501

info@bookergliding.co.uk

8.33 Radio Information

  • Use the short cuts below to scroll down the page for radio comparison chart and links to manufacturers and suppliers etc.





Shortcuts to information on this page.

Background to 8.33
Latest News
List of manufacturers and their radios
Radio feature comparison table
Key to radio features table
Useful links to other 8.33 information
Links to vendor websites





Background to 8.33 VHF band frequency spacing.


Aviation regulators and airspace users have a problem that there are not enough radio frequencies to go around. There is a simple but expensive technical solution, it requires owners/operators to upgrade their radios (also called transceivers) from existing (25Khz) channel spacing to 8.33Khz. In order to drive the change, the EC has published a regulation (1079/2012). To clarify and permit compliance with this EU Law, Regulators and National Authorities provide guidance material. The CAA have a dedicated webpage. In some cases time limited exemptions are obtained to permit a deviation from the law and these are described in the guidance material.







Key info and latest regulatory news.

  • CAA 20% rebate claims process.
  • This document is essential reading if you plan to claim back 20% of your radio cost from the CAA. Labour is NOT included, but accessories are.

  • CAA 20% rebate claims form.
  • Form to be used when claimimng for 8.33 radio equipment.

  • CAA Exemption Request.
  • In December 2016 the CAA requested exemptions for some gliding frequencies. EASA have 6 months to respond to this request so by May 2017 it should be clear whether any 25Khz gliding frequencies will continue after December 2018.

  • Use of 8.33 handheld radios.
  • The CAA will permit the in flight use of certain certified handheld radios for 8.33 communication (in lieu of a fixed installation). These can ONLY be used in uncontrolled airspace or Class D airspace. Handheld transceivers purchased during 2017 may qualify for a 20% rebate with certain terms and conditions.

  • Radio in Class G airspace.
  • There is no change to the rules that permit non-radio flying in class G airspace.

  • When do the frequencies change over.
  • The plan is that, for airspace below FL195, frequencies will be allocated during 2018 and all change over by the end of 2018. It is not clear how and when information about these new frequencies will be promulgated.






    Radio Manufacturer details and key radio features.




  • Becker Avionics

  • Becker avionics is a very well established German Avionics company. The AR6201 is highly configurable and provides probably the most flexibility when setting up the radio for a specific glider. Usability is good. A good reputation for reliability and capability. It is an expensive radio.

    Links below are for the AR6201 webpage, installation guide and operating manual.

  • AR6201 Webpage
  • Becker radio Installation and Operation manual.
  • Becker also provide a retrofit manual for owners that already have a Becker radio installed.

  • Becker radio retrofit manual.



  • TRIG Avionics
  • TRIG Avionics are based on Scotland. The TY91 is a "dual box" system with a small head unit to mount in the panel and a separate box with the radio in. This is a common choice for gliders with limited space directly behind the panel. The unit can easily be operated in a "25Khz only" mode to speed up 25Khz frequency selections. This unit has fewer memories than most, but the unit has an internal database of frequencies and usability can be enhanced if the unit has a compatible GPS feed, it will then offer additional presets based on your location. This unit will NOT work with Dynamic microphones so you may need a new microphone.

    The TY91 can also be installed to a space that is slightly less high than the normal 57mm mount.


    Links for the TY91 Brochure, Operating Manual and the Installation Manual.

  • TY91 Brochure
  • TY91 Operating Manual
  • TY91 Installation Manual


  • FUNKE Avionics

  • FUNKE Avionics is part of a larger group of German companies, the company structure has changed significantly over the past few years. Some of their radio pedigree comes from the Filser company which they took over in 2007 (Filser built the ATR500). They have three 8.33 radios suitable for gliders; ATR833 with suffixes -OLED, LCD, S.

  • ATR833- webpage
  • ATR833-OLED Installation and Operation manual
  • The ATR833 OLED is the original version of ATR833. May need to evaluate the readbility of the display in bright sunlight.

  • ATR833-LCD Installation and Operation manual
  • The ATR833 LCD version has a monochrome display and is slightly cheaper than the OLED version. Otherwise the LCD and OLED are virtually identical.

  • ATR833-S Installation and Operation manual
  • The ATR833 S is a brand new, low cost, simple to use 8.33 radio. It has an interesting plastic housing. There are very few in the UK at the time of writing (Feb 17). The unit will automatically detect the type of microphone in use.


  • DITTEL - TQ Avionics.

  • Walter DITTEL Gmbh was founded in 1959 as an aircraft radio manufacturer, but they don't make radios any more! In 2013 some of the (legacy FSG*) DITTEL radio business was sold to the same company as FUNKE. The DITTEL Avionics business was then sold to the TQ Group in mid-2016 to create TQ Avionics who now manufacture and support the KRT2 radio.

    Early models of the KRT2 had a smaller display size than the current model. This radio is one of the least expensive, but still offers a large number of features. Named presets can be loaded using a Windows PC program. Some find the display rather busy and dislike the use of a single knob for volume, tuning etc. The control is very close to the display. A large number of adapters are available to permit installation of this radio into existing wiring. In some cases the KRT2 adapters have isolation transformers in the speaker wiring and these can significantly reduce the volume of the radio; it may be better to re-wire rather than use an adapter.

    You will see from the pictures on the KRT2 webpage below, that the KRT2 is also available with different "mini format" mounting options and control layouts for panels with limited space.


    Links for the Dittel KRT2 webpage, User and Installation Manual.

  • Dittel KRT2 webpage
  • KRT2 User Guide and Installation Manual.




  • All of the radios in the table below have the following common features.


  • install into a 57mm panel mounting hole.
  • 6 Watts of RF radio energy output.
  • Dual Watch (see below for more info).
  • are certified and valid for the 20% CAA Claim.


  • A key to the rows in the table is provided below.


  • Length
  • In all cases above, the unit length excludes the connectors. All of the radios have the connectors mounted on the rear. Add approximately 60mm to the length when checking for clearance. These units are shorter than the 25Khz units so you may wish to check that existing cables have some slack in to make up the distance.

  • Microphone types.
  • Std - Standard Aviation(Carbon) - need to have a DC bias voltage applied and have a signal output of about 0.5 - 1 volts. The bias voltage is provided by the transceiver on the same wire as the signal. This input would also be used for Electret microphones, though the Electret needs a high output.

    Dyn - Dynamic - This input will not supply a bias voltage and is the most common type for gliders.

    Auto - Some transceivers can automatically detect the microphone type, though it can also be set manually.


    Until a few years ago there were two commonly used microphone types, Aviation Standard(Carbon) and Dynamic (Moving Coil). Most gliders were fitted with Dynamic microphones, usually in the form of a silver "Swan Neck" with a lump on the end about 50mm long and 20mm diameter.

    In the last few years the Electret microphone has come into use and has become popular, it is smaller and more robust.

    If you are lucky, your existing microphone type may be recorded in your paperwork somewhere. To summarise -

    If retrofitting, ask the supplier about compatibility with your transceiver.

    A black microphone may give fewer reflections.

  • Power to Speaker.
  • All of the radios are 4 watts or more. This output power is an approximate measure of how loud the radio is. In reality they are all likely to be of similar loudness (this is defined in the specification to which they are certified). Your loudspeaker must be capable of absorbing 4 watts of power. If it cannot, and you blow it up listening to ATIS at full volume, a replacement is cheap.

  • Dual Watch.
  • Listen and talk on the tuned frequency whilst also listening to the standby frequency. Can be switched off if not required.

  • Display type.
  • You may wish to consider your "view" of the radio, is it high in the panel, easy to see but exposed to sunlight, or down low and at an angle?

    LCD are monochrome displays. They use little power and are easy to read in direct sunlight, though not so easy to see in very dim light. Sometimes they become hard to read (lower contrast) in the cold.

    OLED displays are bright and colourful (like a Samsung phone) but they may be tricky to read in direct sunlight.

    IPS displays are bright and colourful (like a Tablet) but they may be tricky to read in direct sunlight. They can be viewed from wide angles.

  • Memories
  • The number of frequencies/channels that can be saved as memorised pre-sets. Some radios will also automatically save the most recently used frequencies for recall from memory. Once 8.33 is fully implemented there will be a lot of 8.33 channels, 2280, and the channel numbers have an extra digit. Memories may become more useful.

  • Memory label chars
  • The number characters that can be used to name a frequency stored in memory.

  • PC Upload
  • Memories and associated data can be uploaded from a PC.

  • Audio Input
  • You can play an external audio signal through the radio (vario, motivational audio etc) and it will automatically be muted when you transmit on the radio.

  • LXnav Radio Bridge
  • Enables you to control and tune the radio from the airfield list, or moving map, of an LXnav flight computer. You can also display the Standby and Active frequencies in "info boxes".

  • Zeus/Eos
  • Enables you to control and tune the radio from the airfield list, or moving map, of a Zeus flight computer. You can also display the Standby and Active frequencies. There may be limitations on which other equipment can be connected to the Zeus when using this feature.

  • GPS Tune
  • When fed with a GPS signal the radio will offer channels for stations that are closest to you. This is a feature of the TRG 91 which has an internal database of channels.

  • Set 25Khz
  • Panel controls enable you to set the radio to operate in 25Khz only mode. Makes it easier and quicker to set frequencies whilst we are still living in pre 8.33 world. (Note 5) For the ATR833-S you need to go into the configuration to select this.

  • Fuse
  • The external (wiring) fuse suggested by the manufacturer. Your 12v wiring must be capable of carrying this current. Power connections should be well made as radios will draw 2 amps when transmitting.

  • Low Batt Warning
  • The value it comes on at. A programmable/configurable setting may be of interest to Lithium battery users.

  • Min OP V
  • Minimum voltage that the radio will transmit at. Many radios will also have a voltage below which they have reduced functionality. For instance (3) although the Becker transmits at 9v the speaker is cut off below 10v.

  • Power in Standby
  • Power consumed when the radio is switched on but not transmitting or receiving. If your glider previously had a radio installed then your new radio will probably consume less power during a typical flight.

  • Warranty
  • Manufacturers or Vendors may offer different warranty periods.