ANAN-10 PA IMD performance

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Conrad_PA5Y
Posts: 79
Joined: Fri Jan 19, 2018 8:11 pm

ANAN-10 PA IMD performance

Postby Conrad_PA5Y » Sun Aug 12, 2018 7:48 pm

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.

Image

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?

Image

Now 50 MHz same output level:

Image

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

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
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DL2XY
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Joined: Sun Jul 30, 2017 9:47 am

Re: ANAN-10 PA IMD performance

Postby DL2XY » Sun Sep 16, 2018 7:09 pm

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
10m_Hermes_80%.jpg (104.98 KiB) Viewed 140 times



PA output at 80W, presdistortion off
10m_80W_PSoff.jpg
10m_80W_PSoff.jpg (115.54 KiB) Viewed 140 times



PA output at 80W, predistortion on
10m_80W_PSon.jpg
10m_80W_PSon.jpg (114.49 KiB) Viewed 140 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
Helmut
Posts: 1
Joined: Sat Jul 15, 2017 3:08 pm

Re: ANAN-10 PA IMD performance

Postby Helmut » Tue Sep 18, 2018 7:40 am

Conrad,

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

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

So there must be something wrong with the PA saturation perhaps....

Can´t help you more..

73 Helmut
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DL2XY
Posts: 24
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Re: ANAN-10 PA IMD performance

Postby DL2XY » Tue Sep 18, 2018 3:31 pm

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
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Re: ANAN-10 PA IMD performance

Postby administrator » Wed Sep 19, 2018 1:59 am

Conrad,

Are your measurements taken with PureSignal enabled?
f6dro
Posts: 8
Joined: Sun Sep 09, 2018 12:39 pm

Re: ANAN-10 PA IMD performance

Postby f6dro » Sat Sep 22, 2018 5:34 pm

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
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Re: ANAN-10 PA IMD performance

Postby administrator » Sun Sep 23, 2018 3:57 am

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
Posts: 8
Joined: Sun Sep 09, 2018 12:39 pm

Re: ANAN-10 PA IMD performance

Postby f6dro » Sun Sep 23, 2018 10:15 am

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
Posts: 8
Joined: Sun Sep 09, 2018 12:39 pm

Re: ANAN-10 PA IMD performance

Postby f6dro » Sun Sep 23, 2018 4:55 pm

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

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