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Si5351 reception reports

 
Edited

I have made some changes to the code I found in this group's file download section to do some testing. I am deciding whether I would need to increase the RF output of the SI5351 to ensure its reports are heard during a balloon mission. I am still waiting for parts to build the amplifier to get 200-500 milli-watts output to the antenna.

In the mean time, I have been running a WSPR transmitter using a SI5351 module with the output at about 10 mW. I am in northwest Ohio, USA, and have received reception reports from Alaska to Germany to Brazil; over 1000 reports a day. So I'm not sure if spending the additional amperage would be worth it when sunshine and supercaps are all I have for a power supply.

My antenna right now is longer than what I will have on the flight, but it's fun to check out the results. If interested, check out the W8AN TX reports at and .

The transmitter is just an Arduino Nano connected to a generic Si5351 module. There is a GoouuuTech GT-U7 GPS module attached for position and time information. My antenna is a 160 meter off-center-fed Windom up about 35 feet. I do have 5 low pass filters from that are switched in based on the band of transmission.

Steve S
 

To my experience there is no need for an amplifier, even at the moste remote areas of the world Im getting a lots of spots runnig the 5351 barebone, Im using 20m band and cut the antenna to regular formula with the 95% shortening of the legs, longest spots heard is 19000km, and I have got a couple of +17000km spots whitch says some of the benefits of wspr :)??

A friend of mine that flow on the south hemisphere (mostly water) used a simple bs170 as a an amp to get a few more db:s out, se attached pic of one of his earliest trackers.

/Mikael

bb02a.jpg

 

Hi Steve,

I think that adding an amplifier would be overkill for this. You would be draining your batteries much quicker and adding another potential point of failure. The 10mw output has been proven in other similar designs to be sufficient. I would also suggest using 1 band of operation in the balloon, adding many filters and a switching system to the output of the SI module would add excess weight to your balloon. For a first launch go as inexpensive and as simple as possible, learn from the mistakes and make something better the second time. For my first launch I considered sending up a simple beacon without gps telemetry as a proof of concept test of the code.?

When things progress, maybe a 2-way relay, basically a low power, low altitude? hf satellite would be an interesting advancement of the project.?

Keep us updated

Stephen

On Sat, Mar 23, 2019, 12:57 AM Steve S via Groups.Io <stu61957=[email protected]> wrote:
I have made some changes to the code I found in this group's file download section to do some testing. I am deciding whether I would need to increase the RF output of the SI5351 to ensure its reports are heard during a balloon mission. I am still waiting for parts to build the amplifier to get 200-500 milli-watts output to the antenna.

In the mean time, I have been running a WSPR transmitter using a SI5351 module with the output at about 10 mW. I am in northwest Ohio, USA, and have received reception reports from Alaska to Germany to Brazil; over 1000 reports a day. So I'm not sure if spending the additional amperage would be worth it when sunshine and supercaps are all I have for a power supply.

My antenna right now is longer than what I will have on the flight, but it's fun to check out the results. If interested, check out the W8AN TX reports at and .

The transmitter is just an Arduino Nano connected to a generic Si5351 module. There is a GoouuuTech GT-U7 GPS module attached for position and time information. My antenna is a 160 meter off-center-fed Windom up about 35 feet. I do have 5 low pass filters from that are switched in based on the band of transmission.

Steve S

 

Mikael, was your friend using the modified U3S firmware from QRP labs? It seems like many balloon builders use this firmware. I tried to obtain it one before, but the author is no longer releasing it and it have never been open source.?


On Sat, Mar 23, 2019, 4:04 AM Mikael Dagman <mikael_dagman@...> wrote:
To my experience there is no need for an amplifier, even at the moste remote areas of the world Im getting a lots of spots runnig the 5351 barebone, Im using 20m band and cut the antenna to regular formula with the 95% shortening of the legs, longest spots heard is 19000km, and I have got a couple of +17000km spots whitch says some of the benefits of wspr :)??

A friend of mine that flow on the south hemisphere (mostly water) used a simple bs170 as a an amp to get a few more db:s out, se attached pic of one of his earliest trackers.

/Mikael

 

Yes, He used the modified version of u3s fw.

Hans Summers qrp-labs is going to release a commercial version of this u3b probably sometime closer to the fall.



/Mikael
 

Well I hadn't found much information on how much RF power was being used on the flights that I had read about which is why I set up the test circuit. Same with the multiple bands. I wasn't planning on putting more than one low pass filter in the system but may just go with 2 bands and put a trap filter in the antenna wire using SMD components.

I agree the 10mW appears to work quite well. I had at one point set the Si5351 at its lowest power level and put a resistor network on its output to get 1mW on the antenna. I was still getting reports over 4000km away.

Steve S

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