Low power out on new build 60/40/30/20 rig

General discussion and support for the Peaberry SDR V2.

Low power out on new build 60/40/30/20 rig

Postby smull » Tue Mar 17, 2015 6:49 pm

I just finished building a V2 60/40/30/20 PB. I put HDSDR in AM mode and keyed the transmit button. With a 14 v battery and a 50 Ohm dummy load I got the following results. I measured the waveform peak to peak on a scope.

20 Meters: 0.3 Watts
30 Meters: 1.15 Watts
40 Meters: 0.63 Watts

I was expecting better results than this, particularly on 20 Meters. The manual says to expect close to 1 W on 20M.

What can I do to get better results on 20 Meters (and 40M)?

Thanks!
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Re: Low power out on new build 60/40/30/20 rig

Postby W4MMP » Tue Mar 17, 2015 8:59 pm

Hi,
First put HDSDR into FM mode. HDSDR limits the output power in AM mode. Set HDSDR to FM and output power sider to maximum and see what you get.
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Re: Low power out on new build 60/40/30/20 rig

Postby smull » Wed Mar 18, 2015 2:21 am

I am glad you mentioned the HDSDR power slider! It only shows up in TX mode. I bumped it to max. On FM the transmission was null. Barely a blimp of signal, even at max. Here is what I got on AM:

20m peak to peak voltage 12v -> 0.36 Watts
30m peak to peak voltage 20v -> 1.00 Watts
40m peak to peak voltage 14.6v -> 0.53 Watts
60m peak to peak voltage 17v -> 0.72 Watts

What did you have your FM set on to get a full power sine wave? Are you sending HDSDR an audio signal to modulate? Is there a way to key CW in HDSDR?

Thanks for the help!
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Re: Low power out on new build 60/40/30/20 rig

Postby AE9RB » Wed Mar 18, 2015 2:35 am

Those levels make it seem like you have multiple errors in construction of the LC filters. I don't see how a single error could cause this.
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Re: Low power out on new build 60/40/30/20 rig

Postby W4MMP » Wed Mar 18, 2015 2:54 am

Um, I don't understand. Push the power output slider to max and click the TX button. The Peaberry will output its maximum power (keep in mind what FM is). As David has pointed out, it appears there maybe issues with the filter components.
Screenshot 2015-03-17 22.40.47_cr-a.jpg
Screenshot 2015-03-17 22.40.47_cr-a.jpg (187.78 KiB) Viewed 6476 times

(Ignore the noise on the RF display).
73
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Re: Low power out on new build 60/40/30/20 rig

Postby nniros » Wed Mar 18, 2015 7:49 am

I had the same problem, i installed R47 68.1ohm and C46 220pF, after I increased the value of C46 to 550pF(220pF+330pF) and now i have this results:
40m I L10 0.56A
30m I L10 0.41A
20m I L10 0.36A

The voltage is 12,97V on L10
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Re: Low power out on new build 60/40/30/20 rig

Postby smull » Wed Mar 18, 2015 3:15 pm

I checked the values of the torids with a LC meter as I put them in and traced them out to make sure they were working. But still I agree it looks like a filter problem. I wish the instructions had the values listed for all the inductors/transformers so I could have checked them all. They are spread well with the right number of turns (double, triple checked). I really do not know what I could have done to make them better.

nniros, what drew your attention to R47 and C46? I assume Q9 is used to isolate or help match impedance to T4 and the keyer but I am guessing here.

nniros, did you write down the power you measured on each of the bands before you made the change from the stock values for R47 and C46? I am interested in how well they match mine. If this result is consistent and reproducible over 60/40/30/20 builds, the instructions should be modified for R47 and C46 to help others.

W4MMP, as far as FM transmission goes, HDSDR did not give a carrier when I pushed TX. I assume the AM carrier is not fully modulated and the FM of course is full amplitude. But I push the slider to max and FM gives nothing. It is weird AM works and FM does not.

Is there a way with usbsoftrock or to give a full amplitude sine wave, or does it just set the freq and xtal calibrations? I have set the PTT in softrock but assume it needs something else to key a carrier. I also have quisk installed and working.

Thanks again for everyone's help. I am getting closer to a finished rig.
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Re: Low power out on new build 60/40/30/20 rig

Postby AE9RB » Wed Mar 18, 2015 5:01 pm

smull wrote:I wish the instructions had the values listed for all the inductors/transformers so I could have checked them all.

See page 4 of the schematic.
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Re: Low power out on new build 60/40/30/20 rig

Postby smull » Wed Mar 18, 2015 5:18 pm

Hmm. My schematic does not have values for T1, T2, T4 or T5. And for T3 it only has the inductance value for the single wrap, not the doubled lines. Does yours?
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Re: Low power out on new build 60/40/30/20 rig

Postby W4MMP » Wed Mar 18, 2015 6:41 pm

I think David was/is referring to only the inductors for the band pass filters.

As for HDSDR not working in FM mode that is a tough one. We all trouble shoot a bit differently, but for me I would get my test tools working first before trouble shooting the Peaberry. FM mode is the only mode I have ever used when testing power issues as it is the only mode that guarantees maximum audio drive (assuming of course the power sider is at maximum). Just as a thought and only a thought is Transmit I/O reversed? It should be. At any rate, as a test , configure HDSDR to use your PC speaker as the "Tx Output". This will tell if HDSDR is generating audio. Set the LO/Tune split to about 1000Hz.
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