Help understanding TX stage

General discussion and support for the Peaberry SDR V2.

Re: Help understanding TX stage

Postby W4MMP » Mon Apr 27, 2015 5:01 pm

Good. Glad it's working.

WSPR and JT65/9, work the world on 1W :D (CW too)
73
Ron / W4MMP
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Re: Help understanding TX stage

Postby mrwizardly » Thu May 14, 2015 12:49 am

It might be right in front of me...but would someone tell me how to switch XMIT I/Q?
I can't seem to find it under the menus in HDSDR.
Thanks
Mark
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Re: Help understanding TX stage

Postby W4MMP » Thu May 14, 2015 1:34 am

Hi Mark,
HDSDR must be in TX mode to show the TX I/Q setting.
73
Ron / W4MMP
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Re: Help understanding TX stage

Postby mrwizardly » Fri May 15, 2015 6:22 pm

Thanks, Ron
Yup!
Found it. RTFM...Read The Flippin' Manual...ha ha ha
Now, I'm suffering from low output. I should be able to blast my XCVR with this 1 watt but it appears that all I'm doing is transmitting with the exciter.
I have checked the following:
Q5-Q6 switching with TX and voltage appears to be the right bias.
Q4-Q10 are switching as well.
The modulation levels are all the same on U7 A-D
Q9 is switching as well and appears to be driving T4. It's difficult to see the modulation.
As the bi-filer windings come out of the binocular transformer (I cant remember my transformer theory) does it matter if either wire goes into which hole?
I know the wide marking on the PCB is for the single winding and the thin lines are for the bi-filer windings.
Just in case, I've matched side to side (beep'd the winding) and matched them that way.
This is where I'm at today.
Mark
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Re: Help understanding TX stage

Postby mrwizardly » Fri May 15, 2015 6:54 pm

This could be one of two things:
Either poor tinning of the binocular leads, or making sure the windings were indeed juxtaposed.
I am getting more output but still not enough to trigger my MFJ-826B SWR/Wattmeter.

Suggestions?

Oh, on AM the PA XSTRs are getting much warmer but I still should be able to peg the S-Meter on my listening radio...especially since the transmitting antenna is the wire running right over the receiver's loop antenna.
Mark
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Re: Help understanding TX stage

Postby W4MMP » Fri May 15, 2015 7:06 pm

Hi Mark,

Hum, as I reviewed this thread it appeared the rig was working. Did something change? Also I'm confused about something else. You mentioned making a contact but how was that possible with the TX I/Q not reversed (as it is now, now that you found the setting)?

At any rate, don't worry about modulation. We will tackle that after we know the rig is making full power. Get yourself a 50 ohm 1 to 5 W carbon resistor. Measure the voltage across it when in FM TX mode. It should be about 20V P-P (on your lowest configured band).
73
Ron / W4MMP
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Re: Help understanding TX stage

Postby mosheen » Fri May 15, 2015 7:24 pm

WFMMP, I'm OP. My rig is working. mrwizardly has continued the thread.

If you're looking for a good power indication, switch HDSDR to CW, slide the slider to full power and hit the enter key while transmitting. I find CW puts out the most raw power for testing.
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Re: Help understanding TX stage

Postby mrwizardly » Fri May 15, 2015 9:31 pm

Everything was going along pretty well.
I took out T4 & T5 and made sure they were not crossed.
VOILA!
I was getting 1 watt out on 14Mhz. As indicated above I should switch to CW mode and press the enter key (poor mans keyer).
I was getting almost 1.3 watts out.
I had even transmitted JT65 with the loop- but the PSK reporter didn't report back that anyone heard me.
I noticed the signal stopped abruptly.
I had been tugging on the coax to get the LOOP cabled in and discovered the PC board had slipped over and touched my metal radio shelve.
The status LED was flashing "I2C" which is "I2C bus failure. Both PCM3060 and Si570 are unreachable"
Oh-man-o-man.
No output now so I guess I managed to blow the FETs in the PA.
So, I'll "should" on myself for not putting down something like a mouse pad or other cover.
That's the end of trouble shooting now til I get some more FETs.
So close yet so far.
Mark
What's the best source for these?
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Re: Help understanding TX stage

Postby mrwizardly » Sat May 16, 2015 12:24 am

Found a local source. These are the same as NTE490 which my local FRY's electronics had.
OK- back to soldering...
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Re: Help understanding TX stage

Postby W4MMP » Sat May 16, 2015 1:36 am

Ah, yes sorry about that. I did watch the posters names closely enough.
73
Ron / W4MMP
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