Radioberry Tx output

[Marc Jatteau]

Hello I use the Rp4 with the Radioberry and pihpsdr but the output power is only 1mW with the Tune. I saw on an advertisement that the output power was 20 mW. With the 5W preamp module the output is only 500 mW. Can we increase the output power of the Radioberry ???. I would like to use it in QRP. 73 by Marc F6GKG

[Samuel Lourenço]

About the Radioberry itself outputting just 1 mW, I can attest that it does output around 10 mW. I had to use a 10 dB attenuator so I could use a 1 W amplifier that I've made, which outputs 1.2 W with an input signal of 0 dBm (1 mW).

As for the 5W preamp, yes, it is a disapointment. I would believe it can produce 1W at the very top, and not suitable for FT8, because it will overheat quickly. I'm planning to do a similar board, but using completely different transistors, directly fed by 13.6 V without having the fragile DC-DC converter in the way.

P.S.: One positive take, I thought that my 1 W, op-amp based amplifier was inneficient. Not any more. It requires about 5W just to output 1.2 W, but it is highly linear up to 100 MHz.

Kind regards, Samuel Lourenço (CR7BIN)

[Joey G.]

I found the low signal out of the radioberry a bit of a challenge to deal with myself.  What I have ended up with is a cheap 2w amplifier after the radioberry feeding a larger  amplifier and filter board feeding my RM Italy 300w amplifier.  I added an adjustable regulator to the first amp to keep the power of the second amp under 10w.  This keeps the RM Italy happy.  20m and below I cut the power to around 5v but above that, I adjust to 6-7 volts.  Seems to work just fine.  Even in digital modes.  I also experienced the 5w preamp board over heating and not being able to sustain a digital transmission.  Even with heatsinks on the transistors.  Seems clunky to have two preamps feeding my large amp but it works.  It's my QTH rig using SDR Console so not so worried about portable.  I'm happy with it.  

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[Ricardo Suarez]

In my radioberry, I use parts of an old, scrapped, FT747. 

The output from radioberry's tx line feeds the amplifier in the scematic attacched, with an PN2222 replacing the missing 2SC2053.

The output of this "preamplifier" is enought to drive the power amplifier form the old FT747 to more than 110 watts on

all bands.

Coils are "green 1/4 watt resistor" type, is easy to mount on 25 x 25 mm piece of experimental board, without any trouble.

Rick LU9DA

El 22/9/2024 a las 09:04, Marc Jatteau escribió:

Hello I use the Rp4 with the Radioberry and pihpsdr but the output power is only 1mW with the Tune. I saw on an advertisement that the output power was 20 mW. With the 5W preamp module the output is only 500 mW. Can we increase the output power of the Radioberry ???. I would like to use it in QRP. 73 by Marc F6GKG

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[Yado-san]

Hi Marc,

Output power can be variable in pihpsdr. (abt.-5dBm to +16dBm @40m band)
> https://groups.google.com/g/radioberry/c/LoCRvkD_wYk/m/O_tKMsJzAgAJ
To begin with, isolate whether there is a problem with the pihpsdr settings or a hardware problem.

The amplitude of your PA is very excellent. 10log(500mW/1mW)=27dB.
In calculation, if the input is 13dBm (20mW), then 13+27=40dBm(=10W) Output!

pihpsdr settings:
 See drive settings, PA settings.(Menu->TX,PA)
 Is it set to maximum output?

Hardware:
In the pihpsdr_TUNE maximum output, observe the AD9866's TX output and after LPF with an oscilloscope or QRP power meter to see where the power drops? Find out.
If RX is OK, the AD9866 is probably OK, Maybe a soldering problem..

Hope this helps
Yado-san, jg1twp

2024年9月22日日曜日 18:04:34 UTC+9 Marc Jatteau:

[Joey G.]

Have you measured the output of this preamp?  I'm interested in building it to replace my existing one.  

Thanks! K5BHD

To view this discussion on the web visit https://groups.google.com/d/msgid/radioberry/320d8ee4-5303-49ce-ad55-fcc9e01fc1d5%40gmail.com.

[Ricardo Suarez]

Hello, Joey

No, I haven't measured it, but is enough power for overdrive an FT747 output module to more than 110 watts on all bands...

Rick LU9DA

[Marc Jatteau]

Hello dear OM. Thanks for the Info 73 by Marc F6GKG

[Samuel Lourenço]

About the Radioberry itself outputting just 1 mW, I can attest that it does output around 10 mW. I had to use a 10 dB attenuator so I could use a 1 W amplifier that I've made, which outputs 1.2 W with an input signal of 0 dBm (1 mW).

As for the 5W preamp, yes, it is a disapointment. I would believe it can produce 1W at the very top, and not suitable for FT8, because it will overheat quickly. I'm planning to do a similar board, but using completely different transistors, directly fed by 13.6 V without having the fragile DC-DC converter in the way.

P.S.: One positive take, I thought that my 1 W, op-amp based amplifier was inneficient. Not any more. It requires about 5W just to output 1.2 W, but it is highly linear up to 100 MHz.

Kind regards, Samuel Lourenço (CR7BIN)

A domingo, 22/09/2024, 10:04, Marc Jatteau <f6g...@gmail.com> escreveu:

Hello I use the Rp4 with the Radioberry and pihpsdr but the output power is only 1mW with the Tune. I saw on an advertisement that the output power was 20 mW. With the 5W preamp module the output is only 500 mW. Can we increase the output power of the Radioberry ???. I would like to use it in QRP. 73 by Marc F6GKG

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