ZachTek WSPR Transmitter – Overview – Pretty Cool.

I was heard in Australia using 200mW and a Gutter, utilizing the ZachTek WSPR Transmitter. Today I would like to give you a 15 minute overview of this device as I have been utilizing it.

What is WSPR? – Weak Signal Propagation Reporter – WSPR (pronounced “whisper”) is an acronym for Weak Signal Propagation Reporter. It is a protocol, implemented in a computer program, used for weak-signal radio communication between amateur radio operators. The protocol was designed, and a program written initially, by Joe Taylor, K1JT. The software code is now open source and is developed by a small team. The program is designed for sending and receiving low-power transmissions to test propagation paths on the MF and HF bands. (Information from Wikipedia –

From ZachTek website ( :

WSPR Desktop transmitter
The WSPR Desktop transmitter is a standalone multi-band WSPR transmitter with built in GPS for the radio amateur/experimenter.

Some quick features:

Standalone operation, PC required for configuration but not for operation.
For transmission on a variety of HF Bands (2-5), based on model and user-choice.
Is powered from USB.
Comes with built-in GPS module and includes external GPS antenna with a 3m (10feet) long cable for easy installation.
Use the PC configuration software to set up your call-sign and band-choice and after that it can operate in standalone mode.
Timing and Maidenhead position is automatic from the GPS network.
Take it camping, move it to another QTH, use it mobile.
Needs only 5V 250mA so can be powered from a phone charger or USB power pack.
Contains an Arduino with open source software.
Software and Schematic is published on documentation page.
Available in four models.
Model Low for bands 2190m and 630m
(136kHz and 474kHz)
Model MidPlus for bands 160m, 80m, 40m, 30m, and 20m

(1.8MHz, 3.5MHz, 7MHz, 10MHz and 14MHz)
Model HighPlus for bands 17m,15m, 12m, 10m and 6m

(18MHz, 21MHz, 24MHz, 28MHz and 50MHz)

Model 80To10 for bands 80m, 40m, 30m, 20m, 17m, 15m, 12m and 10m

(3.5MHz, 7MHz, 10MHz, 14MHz, 18MHz, 21MHz, 24MHz and 28MHz)

Once you have set up your call-sign it will operate independently indoors or outdoors with minimal requirement of interaction from the user.

The GPS provides the timing necessary to ensure that the WSPR transmission is occurring at the correct time. The GPS also provide the position information needed to calculate the Maidenhead code that is transmitted. This is a great feature as it means the users don’t have to know the Maidenhead grid before getting on the air. This can be very convenient if you take the transmitter to a new location or use it in a mobile application.

The output power around 200 mW is just perfect for WSPR operation. With a dipole antenna it will give you continent coverage most of the time but when the conditions are favorable it will give you trans-continent contacts. So at this power level it easy to see how the daily conditions change.
The input power requirements are 5V 100mA at idle and 250mA when transmitting.
This makes it possible to use a laptop computer, phone charger or a USB Power pack to power it in mobile or stationary operation mode.
What better way to test out your portable antennas than to stick this in your backpack with a USB power pack and try out different antennas or mobile QTHs?

The product comes with an external GPS antenna and a USB cable but without a power adapter.

The PC configuration software is available for download form this web or GitHub.


I really like the ZachTek forums, everyone there seems pretty welcoming and eager to share information – (registration is required)

Affiliate Links – If you like these episodes, consider at least clicking the link – – Comet CTC50M Window Feed-Thru Jumper. I will attempt to get a review on this in the future but I can no longer make promises.

Cheap 9:1 unun for lower power / QRP –

Can WSPR Solve Flight MH370 Mystery? I don’t have an opinion and think it was worth at least considering,but here’s some more qualified information –

@davecasler made a video on MH370 with WSPR – />
as did @HamRadioDX

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