The UK Primary 24 GHz or 1.2cms allocation is 24.000 - 24.050 GHz with the centre of the narrow band operating segment at 24.048 GHz. Wideband operation is centered around 24.025 GHz. In addition there is further secondary spectrum between 24.050 and 24.250 GHz of which the first 100 MHz is not currently permitted to be used in the UK. Consequently the Primary allocation is recommended for all current and future usage.
See the RSGB 24GHz band plan for full details.
There are a number of narrow band beacons in the 24GHz band - see this page for an up to date list.
24 GHz Equipment
The easiest way to get on 24GHz is to modify 23 or 26GHz telecom link equipment.
A very good example of this is by G1EHF which shows how simple it is to get on 24 GHz.
Internally, the transverter largely comprises DMC modules from a ex-23GHz microwave link. The synthesiser and filter have been retuned to the 24GHz band, with the preamplifier, intermediate amplifier and power amplifier connected in series. These are then reversed using a coaxial transfer switch between RX and TX, providing a reasonable noise figure on RX and around 100mW on TX. An MM94P mixer and retuned filter are common to both RX and TX paths.
The transverter runs from a single 12V battery and uses an FT817 on 430MHz as the IF
The antenna is by RFS with a gain of around 36dBi.
Putting a system together
Perhaps the first thing to get is your dish as this determines the hardware form factor of your system.
Then collect and test the modules, typically these will be:
- Local Oscillator block plus multiplier
- Receive module
- Transmit module
- Antennae change over system - wave guide or high quality SMA relay.
Local Oscillator requirements
To operate on the NB segment at 24,048.2 MHz the following LOs are required:
- 144 MHz IF = 24048 - 144 = 23,904 MHz (/2 = 11,952 MHz)
- 144 MHz IF = 24048 + 144 = 24,192 MHz (/2 = 12,096 MHz)
- 432 MHz IF = 24048 - 432 = 23,616 MHz (/2 = 11,808 MHz)
- 432 MHz IF = 24048 + 432 = 24,480 MHz (/2 = 12,240 MHz)
DMC modules are used by a lot of operators and there is a lot of information available on the web:
- W6BY has compiled a very useful reference list of DMC part numbers = http://www.qsl.net/w6by/parts/dmc.html
- EB3FRN has some useful info and links http://www.eb3frn.net/?p=118 including details on retuning the locked oscillators and retuning the IF = http://www.eb3frn.net/?p=123
- F1CHF has an extensive Powerpoint describing DMC equipment: http://f1chf.free.fr/F5DQK/6_Transverters/24GHz_DMC_bricks_older.pdf
- DMC-110366 Synthesized 20 GHz Microwave Source Operation Manual File:20Syn_BY.pdf
- Notes on Switch setting for DMC 20 GHz source by Rex Allers, KK6MK File:DMC_SW.pdf
- Part number list and pictures of DMC modules (not all 24GHz) available here: http://www.xertech.net/Tech/DMC/DMC_main.html
- Information on the older 11012* modules here Older DMC Modules
- Moving 23 GHz DMC WG Filters up to 24 GHz DMC WG Filters
A very common unit to generate the 13GHz LO (doubled to 24GHz) is to use the Elcom 1201 synthesiser available from ebay.
- G8CUB has done an excellent article describing their use = http://www.rfdesign.co.uk/microwave/Content/Elcom%20Synth%20article.pdf
- Dave Robinson G4FRE has designed a small PIC interface to program the unit = http://g4fre.com/dfs1201.htm
- Rob M0DTS describes the use of the Elcom 1201 for a personal beacon http://www.m0dts.co.uk/?tag=24GHz
- GM8BJF has developed an Arduino controller for the Elcom: https://gm8bjf.joomla.com/10-articles/11-using-arduino-microcontrollers-to-programme-microwave-synthesisers
- VK2TDN describes the use of an Elcom synthesiser and Thales 23GHz units : http://www.sydneystormcity.com/24GHz.htm
- Croatia Microwave has some tips on getting the Elcom going if yours is faulty : http://croatia-microwave.blogspot.co.uk/2014/10/playing-with-elcom-ceragon-dfs-1201.html
- Locking the Elcom to external 10MHz reference: http://www.vklogger.com/forum/viewtopic.php?f=40&t=10187&start=20#p37834
Thales Alcatel 23GHz equipment
A lot of Thales / Alcatel equipment appeared on the second hand market around 2010.
- John G4BAO wrote an article for Scatterpoint March 2010 on using these units on 24 GHz: http://www.sydneystormcity.com/Thales23GHz.pdf
Other station's systems
- OK1VM has a lot of info and pictures but not in English http://www.ok1vm.cz/projekty/24g.htm
- DL4DTU Budowa system description based around DMC modules http://www.sp6gwb.pl/wp-content/uploads/2011/03/Budowa-transwertera-24-GHz.pdf
- 9A4QV describes his system here http://croatia-microwave.blogspot.co.uk/2014/10/eyal-gal-24ghz-transverter.html