KA1GT Experimental 23cm Beacon

In brief. To receive the Q65 transmissions:
1 - Tune to 1296.199 MHz as the "sked" frequency
2 - Enter "KA1GT" in the Call box and "FN54uj" in the Grid box in WSJTX
3 - Selecy "On Dx echo" Dopper mode ("Full Doppler to Dx" will also work)
4 - This sync tone will be near 1500Hz and the carrier will be near 2000Hz
5- Q65-15A messages will decode with a DT of around zero. This is normal and by design.

NOTE: This test beacon will only be active for short testing periods and only when this is announced on the HB9Q logger

I'm currently testing an experimental 23cm beacon transmitter. The details are as follows:

It can be set to transmit Q65-60C, Q65-30B or Q65-15A. Q65-15A can be sent with timing adjusted for decoding by standard WSJTX - which will not normally decode Q65-15A EME signals because it does not active the "decode after EME delay" option for the 15A mode.

The beacon can also be set to cycle through these modes as described below:

  • It transmits Q65-60C, Q65-30B and Q65-15A in 5 minutes-per-mode sequences
  • At 0, 15, 30 and 45 minutes past the hour it transmits 5 minutes of Q65-60C
  • At 5, 20, 35 and 50 minutes past the hour it transmits 5 minutes of Q65-30B
  • At 10, 25, 40 and 55 minutes past the hour it transmits 5 minutes of Q65-15A with 15s of carrier between Q65-15A transmissions.

The nominal transmit frequency is 1296.200MHz, though it is currently running uncalibrated and will be seen at around 1470Hz if you tune to 1296.199MHz with the Doppler correction for "On Dx Echo" and FN54uj as the DX station grid.

When the Q65 signal is not being transmitted, a carrier is sent which is 500 Hz higher then the Q65 sync tone. When Q65-15A is being transmitted, the signal and carrier alternate every 15s.

Note: The Q65-15A signal for EME is sent with a 2.5 second offset so that it can be decoded after the EME delay. Standard WSJTX does not enable decoding after EME delay for the Q65-15 mode (see https://bobatkins.com/radio/Q65-15_eme.html and https://bobatkins.com/radio/Q65-15_eme_II.html). If you use standard Q64-15A as a mode in WNJTX it will only work for terrestrial contacts with DT around 0. These modified Q65-15A EME transmissions will also decode with a DT around 0, not the 2.5s you would normally expect. The bottom line is that you cannot use standard WSJTX to make Q65-15A EME contacts. I have a modified version of WSJTX that can be used for Q65-15A contacts, but the modifications are not part of any official release of WSJTX.

Heres are extracts from the log of Charlie, DL3WDG who was copying the beacon running this modified timing Q65-15A on a 2.4m offset dish with a non-optimized feed.

I have also receive decode reports from Bill, KB2SA (1.9m optimized dish) at -17dB and from Dwayne, AB6A (2.4m folding dish) at around -21dB. Below is a screenshot from KB2SA

The beacon tests will be with a 3m dish and about 100W at the antenna feed, so will not be strong, but should be decodable with even a small dish if it is well optimized.

I believe the signal is clean and free from spurs. Spurs are always an issue since the Q65 tones are generated directly from a frequency synthesizer. Below is the waterfall spectrum I measured on the output 1296 signal using Map65 and a FunCube. The spreading is mostly an artifact of the SDR receiver and the very strong local signal (not EME).

The weak signal at the sync tone frequency when the +500Hz carrier tone is generated is real and not spurious, however unless you have a very good Rx system with a large dish, you will not see it. The sync tome here is around 780Hz and the carrier is 500Hz higher at around 1280Hz

NOTE: As with any EME beacon transmission, you need to use "On Dx Echo" Doppler mode, and you need to fill in the Call and Grid of the beacon. In this case it is KA1GT and FN54uj. This will setup the correct Doppler shift for the Rx station and will enable AP assisted decoding. Currently, if setup correctly and you tune to 1296.199MHz the Q65 sync tone will currently appear close to 1500Hz and the carrier at 2000Hz. This may change slightly after calibrationand theis data will then be updated.

ALL reception reports are welcome. Especially useful would be saved .wav files ("Save -> Save All" mode selected) or if they are not available, screen shots of the waterfall and decodes.

This test beacon will only be active for short testing periods and only when this is announced on the HB9Q logger.

Basic Beacon Layout

This is the basic beacon structure. MPX is an I2C multiplexer. MCU is the micro-controller. The switch is a fast solid state switch. Synth1 and 2 are I2C controlled frequency synthesizers. The 10MHz frequency references are OCXO or DOCXO modules. The GPS is used for time synchronization (not frequency control). The filters are bandpass filters for 144 MHZ. XVTR is a 144 to 1296 Transverter.The Q65 tones are setup by the two frequency synthesizers and switched by the solid state switch at the appropriate times.