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Major M588 ptbm059 am/fm frequence issue.

Posted: 01 Jun 2017, 12:18
by pienari
I donno what is wrong with Major M588 frequencies,WHY there is so big difference between modulations?.
Powersupply 13.8v

ch20 tx freq
FM 27.204663MHz
AM 27.205043MHz

X1 10.240 crystal freq
10.240000MHz

Compare to Ham multimode 2 ptbm059

ch20 tx freq
FM 27.205518MHz
AM 27.205617MHz

X1 10.240 crystal freq
10.240002MHz

http://ham-international.nuxit.net/PTBM ... glages.htm

Anyone have better alignment brochure?
Edit.

There seems to be a bit different parts on the PTOS006AOX board.

Major
R26 100ohm
R23 18k ohm
R27 2.2k ohm
Multimode 2
R26 680ohm
R23 8,2k ohm
R27 1,2k ohm

Re: Major M588 ptbm059 am/fm frequence issue.

Posted: 05 Jun 2017, 13:05
by pienari
Is anyone having same issue?.
I own 5pcs M588 and all same problem.
Is there some component or voltage diference somewhere why MM2 is a bit better am/fm stability.

Re: Major M588 ptbm059 am/fm frequence issue.

Posted: 06 Jun 2017, 13:54
by Otter
Is there any difference in voltage on the emitter of Q44 when you change modes?

Re: Major M588 ptbm059 am/fm frequence issue.

Posted: 06 Jun 2017, 14:52
by pienari
Not much.
I looked from schema it should be 9,4v
13.8v psu
Major
RX
FM 9.26V
AM 9.27V
USB 9.25V
LSB 9.25V

TX non modulated
FM 9.17V
AM 9.18V
USB 9.20V
LSB 9.20V

MM2
RX
FM 9.60V
AM 9.61V
USB 9.59V
LSB 9.59V

TX non modulated
FM 9.49V
AM 9.50V
USB 9.55V
LSB 9.55V

Re: Major M588 ptbm059 am/fm frequence issue.

Posted: 06 Jun 2017, 16:37
by pienari
I measured a bit more.

TX on IC3 pin 1
Major
FM 10.695002MHz
AM 10.695002MHz

MM2
FM 10.695015MHz
AM 10.695015MHz

So that is fine or maybe a bit high to Multimode.

I think i have to measure voltages if there is something ...

Re: Major M588 ptbm059 am/fm frequence issue.

Posted: 11 Jun 2017, 17:08
by Ashtec
If i was you i would see how the radio is frequency modulated...
ie....By the xtals or is it by a conversion to the vco...
I say this as it looks when in FM mode the frequency is dropping or being dragged down.

Re: Major M588 ptbm059 am/fm frequence issue.

Posted: 11 Jun 2017, 19:11
by 14CS06
Hello Ashtec

Happy to see you here

@+
Claude

Re: Major M588 ptbm059 am/fm frequence issue.

Posted: 12 Jun 2017, 19:18
by pienari
Only 22ohm bias mod on Major.
I donno what mod is made to MM2 but channel guard and maybe some kinda microphone preamp.
I have to look osciloscope and spectrum analyzer how both act with TX.

Re: Major M588 ptbm059 am/fm frequence issue.

Posted: 09 Sep 2017, 07:47
by pienari
Another 588 arrived and this time Black spirit moded.
I have to check this too.

Re: Major M588 ptbm059 am/fm frequence issue.

Posted: 12 Nov 2017, 14:12
by pienari
Problem maybe solved atm.
I have to make aligment again and after that i can say if it helped.

All M588 same issue and manufactured wrong because 9v voltage coming from FM/AM/SSB selector AM without diode and FM thru diode so it drop about 0.5v.

So i added diode both and frequence is really stable . 27.205 FM -> 27.205387 . AM -> 27.205400.

Re: Major M588 ptbm059 am/fm frequence issue.

Posted: 18 Nov 2017, 17:22
by pienari
pienari wrote:
09 Sep 2017, 07:47
Another 588 arrived and this time Black spirit moded.
I have to check this too.
Same issue this one too.

Re: Major M588 ptbm059 am/fm frequence issue.

Posted: 01 Mar 2018, 23:35
by Ashtec
Interesting to know.

Re: Major M588 ptbm059 am/fm frequence issue.

Posted: 02 Mar 2018, 09:21
by cb4ever104
Ashtec wrote:
01 Mar 2018, 23:35
Interesting to know.
Nice to see you back Paul :)

Re: Major M588 ptbm059 am/fm frequence issue.

Posted: 03 Mar 2018, 14:49
by Ashtec
cb4ever104 wrote:
02 Mar 2018, 09:21
Ashtec wrote:
01 Mar 2018, 23:35
Interesting to know.
Nice to see you back Paul :)
Glad to be back..