YL3CAAE
Neuling
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Strange nummbers in Switches bias
« on: 20. May 2018, 20:22:29 »
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Hello.
I got strange nummbers in Bias switch B1
1) Turned on RX, volts on all bands exept 20/30m
2) Turned on RX volts on 20/30m
3) Oms when switched off
If i understand correctly B1 need be same as B2,B3, B4
73
Ilvars
Yl3CAAE
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« Last Edit: 20. May 2018, 20:23:02 by YL3CAAE » |
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DJ3FV
alter Hase
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Never underestimate an old man...
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Re:Strange nummbers in Switches bias
« Reply #1 on: 21. May 2018, 05:59:32 »
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Hello Ilvars,
it would be helpful if you can give us some details about the rig or version of the mcHF you own and talking about.
73, Uwe
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YL3CAAE
Neuling
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Re:Strange nummbers in Switches bias
« Reply #2 on: 21. May 2018, 07:48:50 »
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Hello,
i got v6 board.
73
Ilvars
Yl3CAAE
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YL3CAAE
Neuling
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Re:Strange nummbers in Switches bias
« Reply #4 on: 21. May 2018, 08:44:10 »
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Hello peter,
How i understund Bias circut, on all B1 B2 B3 B4, need be same parametrs, I do not understud why resistance and volts change in B1, all reistors ( R3a R3b R3c R3d )is same size 100k on all circuts
I ask this becouse i got problem with D3 diode in Antena switch, i change it to new but mybe i got some more broken parts what need change.
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| « Last Edit: 21. May 2018, 08:46:05 by YL3CAAE » |
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peter_77
Urgestein
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THE mcHF and UHSDR forum !
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Re:Strange nummbers in Switches bias
« Reply #5 on: 21. May 2018, 09:00:48 »
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Its a standard voltage divider circuit in the bias network. B1 should not differ from B2 to B4 of course. Its all the same.
If you have such a strange difference here you might have a problem at U1 or probably R1 or C1 and a possible solder bridge or wrong component (U1) ?!
D3 is a whole different story. Here you need to pay attention on RFC2 !
In case you put HF on it and have a bad SWR this coil can burn in seldom circumstances. So make sure you use the correct TDK coils here !
Or... do the radical change and make the relais modification to get rid of all pin diode related issues:
https://www.amateurfunk-sulingen.de/mchf-projekt/modifikationen#start
(RF-04/05-H-029)
There are some photos of this modification here in the forum as well.
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| « Last Edit: 21. May 2018, 09:04:51 by peter_77 » |
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YL3CAAE
Neuling
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Re:Strange nummbers in Switches bias
« Reply #6 on: 21. May 2018, 21:01:05 »
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thanks for advise peter
i check r1 and c1 looks it`s ok, ( how i can check in board ) so i order new U1 chip.
About (RF-04/05-H-029) i need little help with D4 antiparallel diodes, i don`t understand how antiparallel diodes work?
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