Topics

RF Power #chat


Andrew Lenton
 

Hi I have just measured the power from my U3S, using an Rhode and Schwarz calibrated NRP 11, the output is after the low pass filter, and I get 75.1mW. I have not mesured the LPF loss but assuming 3dB, so the RF is nearer 150mW, I am not using the switch relay board. The BS 170 is running from 5 Volts. T1 on the U3S is 25 turns Bifilar wound. Is this reasonable or should it be more?

I will measure the LPF later and report.

BR

Andrew G8UUG


g4sra
 

Which band ?

On 01/09/17 15:46, Andrew Lenton wrote:
Hi I have just measured the power from my U3S, using an Rhode and Schwarz calibrated NRP 11, the output is after the low pass filter, and I get 75.1mW. I have not mesured the LPF loss but assuming 3dB, so the RF is nearer 150mW, I am not using the switch relay board. The BS 170 is running from 5 Volts. T1 on the U3S is 25 turns Bifilar wound. Is this reasonable or should it be more?
I will measure the LPF later and report.
BR
Andrew G8UUG


Andrew Lenton
 

Good Point, 20M power set to 23dBm

BR

Andrew


g4sra
 

On 01/09/17 16:57, Andrew Lenton wrote:
Good Point, 20M power set to 23dBm
In case you misunderstood...
the dBm setting in the U3S is purely information to transmit when in WSPR mode. You should set this to reflect the power level you actually measure.

75mW is approx 18dBm.

I have not mesured the LPF loss but assuming 3dB
I would hope that it is less than that, I would expect 1dB LPF loss.


BR
Andrew


Andrew Lenton
 

Thanks for that, I will check the LPF loss, I seem to be a bit low on power, is 75mW reasonable at 5V, if not I will investagate, if ok I will leave well alone. Should I put the rail up to 13.8 Volts for the BS 170? what should I expect?

73

Andrew


Alan de G1FXB
 

Andrew,
Something that leaps of the page, is you describe a 25 turn Bifilar.
The original U3 / U3s used a 25 turn inductor, conventionally wound.
The updated U3s instructions have detailed an alternative Bifilar design with 10 turns.
(But not advised if you intend using in conjunction with Han's PA Kit.)

Was your description a typo or are you aiming to maximise efficiency for the LF bands ?

Have you seen:-

https://www.qrp-labs.com/ultimate3/u3info/u3sbifilar.html

Gives you typical values.


Alan


On 01/09/2017 15:46, Andrew Lenton wrote:
Hi I have just measured the power from my U3S, using an Rhode and Schwarz calibrated NRP 11, the output is after the low pass filter, and I get 75.1mW. I have not mesured the LPF loss but assuming 3dB, so the RF is nearer 150mW, I am not using the switch relay board. The BS 170 is running from 5 Volts. T1 on the U3S is 25 turns Bifilar wound. Is this reasonable or should it be more?

I will measure the LPF later and report.

BR

Andrew G8UUG


Andrew Lenton
 

Dear Alan,

 

No, I intend to use the 25 turn, as I may buy the 5 Watt PA, so what power did you achieve, I am trying to work out if I have a fault or not.

 

73

 

Andrew

 

From: QRPLabs@groups.io [mailto:QRPLabs@groups.io] On Behalf Of Alan de G1FXB via Groups.Io
Sent: 01 September 2017 18:33
To: QRPLabs@groups.io
Subject: Re: [QRPLabs] RF Power #chat

 

Andrew,
Something that leaps of the page, is you describe a 25 turn Bifilar.
The original U3 / U3s used a 25 turn inductor, conventionally wound.
The updated U3s instructions have detailed an alternative Bifilar design with 10 turns.
(But not advised if you intend using in conjunction with Han's PA Kit.)

Was your description a typo or are you aiming to maximise efficiency for the LF bands ?

Have you seen:-

https://www.qrp-labs.com/ultimate3/u3info/u3sbifilar.html

Gives you typical values.

 

Alan

 

On 01/09/2017 15:46, Andrew Lenton wrote:

Hi I have just measured the power from my U3S, using an Rhode and Schwarz calibrated NRP 11, the output is after the low pass filter, and I get 75.1mW. I have not mesured the LPF loss but assuming 3dB, so the RF is nearer 150mW, I am not using the switch relay board. The BS 170 is running from 5 Volts. T1 on the U3S is 25 turns Bifilar wound. Is this reasonable or should it be more?

I will measure the LPF later and report.

BR

Andrew G8UUG

 


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Alan de G1FXB
 

Typical curves for a U3 exciter and LPF's are:-

https://www.qrp-labs.com/ultimate3/u3info/u3spec.html

Either on Han's site or one of the builders site is another more complete set of plots for the LPF's
Care should be exercised with 13.8V on the PA, some method of heatsinking for the PA & care with Bias setting.
I only ever used 9V and the PA heated in my view excessively for a long PA life.....


Alan



On 01/09/2017 17:44, Andrew Lenton wrote:
Thanks for that, I will check the LPF loss, I seem to be a bit low on power, is 75mW reasonable at 5V, if not I will investagate, if ok I will leave well alone. Should I put the rail up to 13.8 Volts for the BS 170? what should I expect?

73

Andrew


g4sra
 

I would expect approximately 150mW on 20m.
Cranking up the PA Voltage is no way to overcome an issue elsewhere.

Follow up on Alan's comments below (well spotted Alan).

On 01/09/17 18:32, Alan de G1FXB via Groups.Io wrote:
Andrew,
Something that leaps of the page, is you describe a 25 turn Bifilar.
The original U3 / U3s used a 25 turn inductor, conventionally wound.
The updated U3s instructions have detailed an alternative Bifilar design with 10 turns.
(But not advised if you intend using in conjunction with Han's PA Kit.)
Was your description a typo or are you aiming to maximise efficiency for the LF bands ?
Have you seen:-
https://www.qrp-labs.com/ultimate3/u3info/u3sbifilar.html
Gives you typical values.
Alan
On 01/09/2017 15:46, Andrew Lenton wrote:
Hi I have just measured the power from my U3S, using an Rhode and Schwarz calibrated NRP 11, the output is after the low pass filter, and I get 75.1mW. I have not mesured the LPF loss but assuming 3dB, so the RF is nearer 150mW, I am not using the switch relay board. The BS 170 is running from 5 Volts. T1 on the U3S is 25 turns Bifilar wound. Is this reasonable or should it be more?

I will measure the LPF later and report.

BR

Andrew G8UUG


Alan de G1FXB
 

A typo. So you have not, a Bifilar wind ?

Typical values for a U3 is:-

https://www.qrp-labs.com/ultimate3/u3info/u3pa.html

The U3S doesn't utilise a second PA switching FET, so efficiency is higher. You should be able to achieve quoted efficiency ?

(Mine is stuck in the past, based on the old  U3 firmware & AD9850 DDS and a different PA utilising the sinewave output.)


Alan


On 01/09/2017 18:56, Andrew Lenton wrote:

Dear Alan,

 

No, I intend to use the 25 turn, as I may buy the 5 Watt PA, so what power did you achieve, I am trying to work out if I have a fault or not.

 

73

 

Andrew

 

From: QRPLabs@groups.io [mailto:QRPLabs@groups.io] On Behalf Of Alan de G1FXB via Groups.Io
Sent: 01 September 2017 18:33
To: QRPLabs@groups.io
Subject: Re: [QRPLabs] RF Power #chat

 

Andrew,
Something that leaps of the page, is you describe a 25 turn Bifilar.
The original U3 / U3s used a 25 turn inductor, conventionally wound.
The updated U3s instructions have detailed an alternative Bifilar design with 10 turns.
(But not advised if you intend using in conjunction with Han's PA Kit.)

Was your description a typo or are you aiming to maximise efficiency for the LF bands ?

Have you seen:-

https://www.qrp-labs.com/ultimate3/u3info/u3sbifilar.html

Gives you typical values.

 

Alan

 

On 01/09/2017 15:46, Andrew Lenton wrote:

Hi I have just measured the power from my U3S, using an Rhode and Schwarz calibrated NRP 11, the output is after the low pass filter, and I get 75.1mW. I have not mesured the LPF loss but assuming 3dB, so the RF is nearer 150mW, I am not using the switch relay board. The BS 170 is running from 5 Volts. T1 on the U3S is 25 turns Bifilar wound. Is this reasonable or should it be more?

I will measure the LPF later and report.

BR

Andrew G8UUG

 


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SM7ETW Jan
 

Andrew, if you have 25 turns they should NOT be bifilar wound it should be conventionally wound, check the manual again.

Andrew PLEASE STOP transmitting on every time slot, you are blocking the frequency totally for others! It is considered ill manners if you do! You should have a pause at lest 6 minutes long preferably 10 minutes between transmissions (they could be spent transmitting on other bands).

I should not be surprised if you can use your 14 MHz LP while transmitting on 10 MHz with the overtones still acceptable down, you can check that with your nice instruments. 

Good luck with the pwr problem.

73 Jan


Andrew Lenton
 

Hi Jan,

You are correct I am using 25 turns single turn not Bifilar, I have Frame to 10 10, what setting to you recomend?

73

Andrew


Andrew Lenton
 

Ok Jan Noted,

 

What setting do I set to get a 10 minute pause? Is it the frame start setting?

 

 

73

 

Andrew

 

From: QRPLabs@groups.io [mailto:QRPLabs@groups.io] On Behalf Of SM7ETW Jan
Sent: 01 September 2017 19:50
To: QRPLabs@groups.io
Subject: Re: [QRPLabs] RF Power #chat

 

Andrew, if you have 25 turns they should NOT be bifilar wound it should be conventionally wound, check the manual again.

Andrew PLEASE STOP transmitting on every time slot, you are blocking the frequency totally for others! It is considered ill manners if you do! You should have a pause at lest 6 minutes long preferably 10 minutes between transmissions (they could be spent transmitting on other bands).

I should not be surprised if you can use your 14 MHz LP while transmitting on 10 MHz with the overtones still acceptable down, you can check that with your nice instruments. 

Good luck with the pwr problem.

73 Jan


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SM7ETW Jan
 

Hi Andrew

I think your problem is the 10 10 setting, the first ten should make a cycle of 10 minutes so that is correct, possible values for the second parameter can then be 0,2,6,or 8 minutes as each frame takes 2 minutes, I think your second 10 upsets the timing so it transmits on every frame (and no time for calibration).

Jan


SM7ETW Jan
 


The following is my U3S without any LPF, bias adjusted to keep overtones down.
The overtone values are dB down from main carrier.

U3S  all values in dBm          
Frequency kHz Power out dBm 2nd overtone  3rd overtone 4th overtone 5th  overtone
137 22.6 -29.1 -8.9 -36.7 -14
475 23.6 -27.6 -9.4 -33.1 -14.1
1900 23.8 -35.5 -9.66 -39.8 -18.2
3600 23.9 -36.8 -9.9 -37.5 -14.6
5300 23.6 -36.5 -9.6 -35.1 -14.6
7100 23.9 -34.3 -10.1 -32.2 -15.1
10130 23.8 -30.8 -10.2 -26.8 -15.6
14100 23.5 -25.9 -10.4 -22.5 -22.3
18100 23.4 -22.9 -10.7 -19.2 -25
21100 23.2 -20.6 -11.2 -19 -26.9
25000 23.2 -17.6 -13.0 -19.7 -39.2
28500 23.1 -15.5 -15.3 -21.6 -39.1
50100 21.3 -17.3 -36.3 -28.3 -21.3
70100 18.8 -17.8 -23.8 -24.8 -18.8
145000 10.8 -13.3 -25.8 -10.8 -10.8
200000 9.1 -9.1 -9.1 -9.1 -9.1
220000 6.2        
230000 8        


Alan G4ZFQ
 

Andrew.

You really need to read the manual.
"You could set the “Frame” setting to 10. This means that after the message
transmission has completed, the microcontroller will wait until 10 minutes after the message start, before starting the next transmission."

Then you do not get replies from people who have not recently reminded themselves.
I think you said you have 10 00. The manual says this will give NO wait period, 100% TX.

10 10 gives 10 minutes between transmissions.

73 Alan G4ZFQ

I think your problem is the 10 10 setting, the first ten should make
..... Not correct


Alan G4ZFQ
 

SORRY
I quoted the manual then got it wrong!!!

"Frame" is the first figure and should not be 00 (Start is the second figure I read too quickly.)

Manual:- "Default: the default value is 00 which means no frame size is defined, and the stacking feature is not used. All mode/frequency combinations are sent repeatedly in sequence. Frame must be set to a non-zero value for WSPR,"


You really need to read the manual.
"You could set the “Frame” setting to 10. This means that after the message
transmission has completed, the microcontroller will wait until 10 minutes after the message start, before starting the next transmission."
RIGHT:- 10 10 gives 10 minutes between transmissions.

73 Alan G4ZFQ


Alan G4ZFQ
 

RIGHT:- 10 10 gives 10 minutes between transmissions.
Trying to get this done quickly I keep making it longer but to finish:-

10 00 gives 100% TX.

73 Alan G4ZFQ


SM7ETW Jan
 

Alan is correct.
I did not look at your picture that says 10 00 I only looked at what you wrote their you said you used 10 10, I trust the picture was correct as that agrees with the loggins.

Jan


KEN G4APB
 

Hi Alan, I think you are missing the way FRAME works;
The first number 10 00 is the time each 2 minute WSPR transmission frame starts, i.e 10 mins past the hour, then 20 mins 30 mins and so on, it is not a continuous 10 minute transmission.
The second number is the offset from 10 minutes i.e 10 02 would start you at 12 minutes past the hour, then at 22, 32 42 minutes etc.
There is no timing randomisation in the U3, so to avoid on-air clashes, you would use the offset number.

FYI, to be annoying and get a transmission every slot would be to use 02 00.

In answer to the CAL time question, FRAME is not the place to set this, it is under CAL, Set to 30 240 to start, (a 240 second cycle), then reduce to 10 240, then 01 240 as the calibration error shown at the end of a cal cycle reduces. Ensure GPS cal mode is also set in the GPS [mode] screen.

73 Ken G4APB

-----Original Message-----
From: QRPLabs@groups.io [mailto:QRPLabs@groups.io] On Behalf Of Alan G4ZFQ
Sent: 02 September 2017 07:07smission
To: QRPLabs@groups.io
Subject: Re: [QRPLabs] RF Power #chat



RIGHT:- 10 10 gives 10 minutes between transmissions.
Trying to get this done quickly I keep making it longer but to finish:-

10 00 gives 100% TX.

73 Alan G4ZFQ