After having a play with WSPR using WSJT-X, and after reading a glowing review of Zachtek's 80To10 model WSPR transmitter, I decided to break the bank and purchase one for myself! 😊
It is basically a 200mW, multi band hopping, standalone WSPR beacon transmitter .. that also doubles as a precision signal generator.
I thought it would be ideal to run through my fan dipoles - 40, 20, 15 and 10m - and give me a great picture of conditions across these bands during the course of a day.
A PC is only required for the initial set-up, which is very straightforward. A supplied active GPS antenna picks up a signal for positional and timing purposes and once it has a lock, the transmitter gets on with the business of beaconing on the selected bands.
Current draw is around 100mA at idle and 250mA whilst transmitting, and a phone charger makes a suitable power source, when not running from a PC USB port.
I did have some 'teething troubles' because I was having a combination of low GPS satellite signal strength and potential RFI blocking .. made worse by the poor signal level. After a re-positioning of the antenna puck, all was working absolutely fine!
All in all, an excellent piece of equipment for accurate and informative propagation studies!
And my thanks to Harry for quickly guiding me to relocate the GPS antenna when I was convinced it was something more serious! 🙂
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Please look at the updates further down the page to follow my progress
with 'fine tuning' and getting things working satisfactorily.
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I now have the Zachtek transmitter working, and beaconing on the 40, 20, 15 and 10m bands.
It cycles from one band to the next and I have a 120 second break after the 4 band cycle before the process starts again.
I'm achieving some astonishing distances, bearing in mind the output power is only 200mW, or 23dBm.
When I've accrued more data, I want to try and see how each of these bands varies, propagation wise, throughout the day.
Here are some 2D plots for each of the bands.
Click on the images to see them full size! 😉
40m
UPDATE! - 4th February 2022
I now have the Zachtek transmitter working standalone and have collected - at the time of writing - around 6 hours of continuous data.
Here is a map - with band key - showing just where I am reaching.
Click on the image to see it full size! 😉
UPDATE! - 8th February 2022
After running in to some issues regarding the transmitter 'freezing' after some 8 to 10 hours of operation, all appears to now be resolved.
I contacted Harry Zachrisson at Zachtek and appraised him of what was occurring.
After a protracted period of running the transmitter, it would just cease beaconing. The first time it happened I was able to get it to restart by removing the charger connection, plugging it back into my laptop and running the configuration software. I could see it polling the ‘visible’ satellites and then getting a positional lock.
To me, it seemed as if the device was perhaps drifting and losing the GPS position/timing signal. Harry suggested it was far more likely that the GPS antenna was picking up RFI and that, combined with the fact that I was receiving only a very weak satellite signal anyway, was the cause of the failed beaconing.
I relocated the GPS head and used double sided tape to secure it to the window glass. Then I powered up the transmitter and monitored it during a 12 hour plus period; it worked fine!
Panic over. 😃
