logo
Welcome, Guest. Please Login or Register.
23. June 2024, 01:17:11


Home Help Search Login RegisterWIKIUHSDR Download

Amateurfunk Sulingen
Diskussions- und Newsboard des DARC-Ortsverbandes I40  |  allgemeine Kategorie  |  OVI40 SDR Projekt (English AND German discussions around OVI40 SDR project) (Moderators: DF8OE, DL1PQ)  |  Topic: PA calibration problem <- zurück vorwärts ->
Pages: [1] Go Down Print
   Author  Topic: PA calibration problem  (Read 2796 times)
f5ugq
Neuling
*

Offline

Posts: 13





View Profile E-Mail
PA calibration problem
« on: 04. April 2019, 18:26:45 »

Hi all,

I'm trying to do the "PA calibration" step following the procedure https://github.com/df8oe/UHSDR/wiki/Adjustment-and-Configuration-Manual#pa-power-calibration. PTT pressed, I've got a current of 460mA, so I must ajuste the PA Bias to 960 (460 + 500) but I can only go to 115. Any suggestion ?

73's, Stéphane, F5UGQ.
Logged
SP3OSJ
Guest

E-Mail
Re:PA calibration problem
« Reply #1 on: 04. April 2019, 18:43:53 »

Hi

Do you have good RD16HHF1 transistors?

http://sp3osj.kooikerhondje.com.pl/zdjecia/49.jpg

73
Artur
Logged
f5ugq
Neuling
*

Offline

Posts: 13





View Profile E-Mail
Re:PA calibration problem
« Reply #2 on: 04. April 2019, 18:57:18 »

Hi Artur,

Thank's for your reply and after verification I've got the  .... bad ones  . I didn't known that  there were somes. I will order the good ones.

73's, Stéphane, F5UGQ
« Last Edit: 04. April 2019, 19:01:25 by f5ugq » Logged
peter_77
Urgestein
*****

Offline

Posts: 735



THE mcHF and UHSDR forum !

View Profile
Re:PA calibration problem
« Reply #3 on: 05. April 2019, 16:02:44 »

If you want to be sure Box 73 in Berlin has them:
https://www.box73.de/product_info.php?products_id=1260
Logged
f5ugq
Neuling
*

Offline

Posts: 13





View Profile E-Mail
Re:PA calibration problem
« Reply #4 on: 06. April 2019, 09:36:19 »

H Peter,

I ordered them yesterday at Box 73  .

73's, Stéphane, F5UGQ.
Logged
f5ugq
Neuling
*

Offline

Posts: 13





View Profile E-Mail
Re:PA calibration problem
« Reply #5 on: 20. May 2019, 18:13:35 »

Hi all,

I received the new transistors, from Box 73, and solded them on the RF board but I have still a problem in the PA calibration. I've got 560mA with a 13.8V supply and when I proceed to the calibration phase, I'm using the CW paddle for TX, the current don't move, it's still 560mA. I added 3k3 resistor between pin 1 and 4 of the U18, like mentionned in section FAQ PA Bias of the link https://github.com/df8oe/UHSDR/wiki/Adjustment-and-Configuration-Manual#pa-power-calibration, but same result, I don't try the 2k2 resistor yet.

Is somebody have an idea ??

73's, Stéphane, F5UGQ.
Logged
DF8OE
Administrator
*****

Offline

Posts: 6265



Stellvertr. OVV I40, Jugend / Nachwuchsreferent

View Profile WWW
Re:PA calibration problem
« Reply #6 on: 21. May 2019, 05:56:21 »

You can neither use CW paddle than TUNE for calibratiing the PA BIAS. Why? In both cases RF is produced and you need TX without RF!!!

Please switch to SSB, reduce Mic gain to "0" and press PTT on MIC. Now turn PA BIAS to lowest number and read the current which is consumpted by the whole TRX. Your task is now increasing PA BIAS so that it is ~0.5A higher than the level you got before.

Physics behind PA calibration are quite simple:
MOSFETS are becoming lower inner resistant if voltage at gate pin increases > ~2.9V. So you can check if gate voltage increases when you crank up PA BIAS. At the other hand you can check if 13.8V goes by nearly 0R to drain pin of MOSFETS - that is all which you need to test.

vy 73
Andreas
« Last Edit: 21. May 2019, 06:14:58 by DF8OE » Logged

Wenn der Wind des Wandels weht, nageln die einen Fenster und Türen zu und verbarrikadieren sich. Die anderen gehen nach draußen und bauen Windmühlen...
qrz.com-Seite von DF8OE
-----------------------------------------------------
>>>> Die Inhalte meiner Beiträge dürfen ohne meine explizite Erlaubnis in jedwedem Medium weiterverbreitet werden! <<<<
f5ugq
Neuling
*

Offline

Posts: 13





View Profile E-Mail
Re:PA calibration problem
« Reply #7 on: 26. May 2019, 09:32:46 »

Hi Andreas,

Thank you for yours explanations. I changed the CW paddle by the microphone, I had to find one because I din't have one. The gate voltage increase well when I increase the PA Bias value but not the current, and there is no output power. I think there is again a problem with the transistors.

I continue the investigations.

73's, Stéphane, F5UGQ.
Logged
DF8OE
Administrator
*****

Offline

Posts: 6265



Stellvertr. OVV I40, Jugend / Nachwuchsreferent

View Profile WWW
Re:PA calibration problem
« Reply #8 on: 26. May 2019, 09:36:10 »

Hi Stéphane,

gate voltage must increase up to 3.2V. Please take a measure if you press PTT and crank up BIAS adjustment so that gate voltages are ~ 3.2V at the drains of PA transistors to GND. If you see complete Vcc of 12V you do have problems with transistors. If voltage is much lower than 12V your supply chain via inductors and transformers to drains is cut somewhere.

vy 73
Andreas
« Last Edit: 26. May 2019, 09:37:12 by DF8OE » Logged

Wenn der Wind des Wandels weht, nageln die einen Fenster und Türen zu und verbarrikadieren sich. Die anderen gehen nach draußen und bauen Windmühlen...
qrz.com-Seite von DF8OE
-----------------------------------------------------
>>>> Die Inhalte meiner Beiträge dürfen ohne meine explizite Erlaubnis in jedwedem Medium weiterverbreitet werden! <<<<
Pages: [1] Go Up Print 
Diskussions- und Newsboard des DARC-Ortsverbandes I40  |  allgemeine Kategorie  |  OVI40 SDR Projekt (English AND German discussions around OVI40 SDR project) (Moderators: DF8OE, DL1PQ)  |  Topic: PA calibration problem <- zurück vorwärts ->
Jump to: 


Login with username, password and session length

 Es wird die Verwendung von Browsern die auf der "Blink"-Engine basieren und mindestens
1024x768 Pixel Bildschirmauflösung für die beste Darstellung empfohlen
 
Amateurfunk Die Beiträge sind, sofern nicht anders vermerkt, unter der folgenden Lizenz veröffentlicht:
GNU Free Documentation License 1.3 GNU Free Documentation License 1.3
verbindet!
Powered by MySQL Powered by PHP Diskussions- und Newsboard des DARC-Ortsverbandes I40 | Powered by YaBB SE
© 2001-2004, YaBB SE Dev Team. All Rights Reserved.
- modified by Andreas Richter (DF8OE)
Impressum & Disclaimer
Valid XHTML 1.0! Valid CSS!