ANAN-10 PA IMD performance

[Conrad_PA5Y]

Using 2 Tone testing I am a little surprised at the two tone performance of the ANAN-10 at 8W. The TX output however is very good so I wonder if I have a bad PA?

Here are some images:

First 28 MHz from the TX out with the PA disabled this is at the same level that produces 8W PEP in later measurements.



Now 28 MHz at 8W as indicated on the ANAN-10 Power meter I know that it is actually 9.2W PEP but it's less than 10W and should be better?



Now 50 MHz same output level:



Now at 3.5W on 50 MHz as indicated on the meter just about acceptable but still not great.


I expected better, are there any known modifications or adjustments to improve the linearity of the PA. I have seen bias adjustments for the 100W PA but not for the ANAN-10.

73

Conrad PA5Y

[DL2XY]

Hi Conrad,

here are my ANAN100 IMD-tests on 10m band for comparsion.
After purchase i had to readjust bias currents due to poor performance (4 years ago).



Hermes output at 80% drive level, PA off, predistortion off

10m_Hermes_80%.jpg (104.98 KiB) Viewed 19695 times

PA output at 80W, presdistortion off

10m_80W_PSoff.jpg (115.54 KiB) Viewed 19695 times

PA output at 80W, predistortion on

10m_80W_PSon.jpg (114.49 KiB) Viewed 19695 times

On Hermes output i had expected less than -50dBc, this could be related to DAC niquist limit. On lower bands this is much better (-65dBc on 80m).
-30 dBc on PA output at 80W looks reasonable for a transitor-pa at 13.8V supply.
Throwing in PureSignal dramatically improves IMD to -57.5 dBc, which is even better than Hermes direct output!

73 Walter
DL2XY

[DL2XY]

I don´t know how you measured this - analyzer overdriven ?? at 33dBm on Marker 1 ?

Don't worry about the +33dBm, there is a function (Reference Offset) to display the "real world power" on the chart.
I have simply forgotten to do this.

Analyzer should get max -30dBm at Input to show distortion free - but I think you know that.

Depends on analyzer. Standard should be about 0 dBm. Don't mistake input level for mixer level, there are internal attenuators.

The standard procedure to test for overdriven analyzers is to put in additional 10 dB attenuation. If everything on the screen drops down the same amount the measurement was fine. I'm quite sure Conrad had checked for that.

73 Walter
DL2XY

[administrator]

Conrad,

Are your measurements taken with PureSignal enabled?

[f6dro]

Hi all ,

sorry to say , but it is not because pure signal improves IMD that the PA can be that bad without pure signal. Maybe quiescent current is wrong?

73
Dom

[administrator]

There is nothing proprietary about the PA design, increase the bias for better IMD without PS, however, PS works best with 250mA bias (each MOSFET). Not sure why one would run the rig without PS enabled?

[f6dro]

Hi all ,

I don't know about Conrad , but in my case:

I am a V/U/Shfer.
The anan is used as a IF , with some power out because all my transverters are far away from the shack.

There are several bands using antenna 1 and this antenna 1 port is switched on 13/6/3cm transverters.
Antenna 2 goes on the 23 cm transverter
Antenna 3 goes on the 1.2cm transverter.
If I would like to run pure signal , it would be very complicated , I need couplers everywhere on every bands and these with coupling enabled coming from 3 different towers.
For me , it is much simpler to get a reasonnable IMD from the tx without pure signal.
Next week , I'll try to measure my TX IMD , I haven't done yet.
73
Dom

[f6dro]

Hi all agn ,

I've measured today the IMD on 28Mhz on the low power output with PA disabled. I get the same numbers than PA5Y. I could not do the measurement with the power amplifier as I have a problem there : no more output since I have upgraded to a new firmware and a new HPSDR yesterday. Will do when it is solved ( yes , I know , Murphy rented a room in my farm , he is always around).
73
Dom

[f6dro]

Hi guys ,

not sorted of the pa problem.
After firmware and software upgrade , I get the rigth power out of the Hermes , but no power at all out of the 10w amp. I can hear a relay click when I press TUNE but no power out. I reviewed all the software configuration and all looks ok.
I will carry on work on this when I have time.
73
Dom

[w-u-2-o]

Have you tried going back to the earlier versions of software and firmware?

[f6dro]

Hi all agn ,

could sort my tx problem : it was a small connector routing the tx signal from the Hermes to the amplifier which was disconnected.

Now more serious. My ANAN is worse that PA5Y , IMD is -21 relative to one tone on the 3rd order and -33 on the 5th order (at 9W pep).

I find it is another bad surprise after my tx spurs which are at only -60dbC;

This problem can be solved by tuning the quiescent current , I don't know wether it is of easy access on the pa board without taking the amplifier apart?

Abt the spurious pb , Leif SM5BSZ agrees with me to say they are awfull and should be at -90dBc. He suspect this is not an hardware problem but something wrong in the firmware or software.

73
Dom