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TOPIC: No power on HF, but...

No power on HF, but... 04 Apr 2022 12:11 #1

  • sp5gni
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Hello
A few years old SunSDR2 Pro with 1.3.1 update 11 - today I found that I can't transmit on HF. No output power for any emission when PTT or MOX activated. Modulation looks OK - visible on the screen.
But - when BreakIn activated, and key pressed - the power on the output was present!
What could happen? How to fix?
73 Miro SP5GNI
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No power on HF, but... 04 Apr 2022 13:05 #2

  • Rome
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Hello Miro.
Here is the instruction on what to do.
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Роман, Roman
Expert Electronics
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No power on HF, but... 04 Apr 2022 17:32 #3

  • sp5gni
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Hi Roman
I hope it will be enough to find a problem:
1. Case BreakIn active - key on - point1 1,3Vpp; point2 2,8Vpp, Pout 15W
2. Case MOX active - key on - point1 2,4Vpp; point2 0Vpp, Pout 0W
Please let me know your opinion.
Miro SP5GNI
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No power on HF, but... 04 Apr 2022 19:32 #4

  • SM2UHF
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Hi

Probably same issue as the one I had in for repair in my workshop, both finals was blown, replace with new and adjusted everything and it was up and running, sent back to costumer.

My best reg 73
Lars H Flygare
SM2UHF
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No power on HF, but... 05 Apr 2022 06:53 #5

  • sp5gni
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I don't think that finals are broaken, because in the first case the output was OK - 15W!
It may be the relay, which is close to the points 1 and 2.
Roman, can I get a schematic, ar at least the part of it?
73 Miro SP5GNI
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No power on HF, but... 05 Apr 2022 07:02 #6

  • Rome
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Hello Miro.
You don't need a schematic to replace a relay, just check the IN and Out contacts of the K1_A4 relay (IM02GR).
If there is voltage on teh IN contact, but no voltage on the OUT contact, then relay should be replaced.
Роман, Roman
Expert Electronics
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No power on HF, but... 05 Apr 2022 12:05 #7

  • sp5gni
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Hi Roman
I checked the relay K1_A4, it rather works OK.
K1 is normaly ON (during RX). When I press key when BrakIn is active, K1 relay switches OFF, and the signal goes to T1 tranformer. I think in this case it works properly.
But in all other cases (MOX or PTT active), the K1 stays ON all the time, and signal path is open.
It looks like K1 control doesn't work properly.
What do you suggest?
73 Miro SP5GNI
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No power on HF, but... 05 Apr 2022 13:19 #8

  • Rome
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Please clarify, are we talking about only CW signal or all other modes?
CW works only when BreakIn is enabled.
Роман, Roman
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No power on HF, but... 05 Apr 2022 14:22 #9

  • sp5gni
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All modes do not work. Even CW, when BreakIn is not active, do not give RF power.
73 Miro
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No power on HF, but... 05 Apr 2022 15:42 #10

  • SM2UHF
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You need to preheat the pcb before you desolder and replace the relay, so you know

73
Lars
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No power on HF, but... 05 Apr 2022 19:06 #11

  • sp5gni
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Hi
Problem solved!
I started to think again and came to a conclusion, that it looked rather for software, not hardware related problem.
I checked all again and I found, that "TX HF DAC" was set, not "TX HF A3".
I don't know why, I don't know how it happend! I didn't touch this option, at least consciously HI
Sorry...
Anyway happy! Miro SP5GNI
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