Maxcom 30e random frequency

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ChubbyChops
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Maxcom 30e random frequency

Post by ChubbyChops »

Need advice (2nd opinion) please.
Maxcom 30e works fine and on frequency on all channels when cold, but, when warm, a few random channels are fixed on channel 24.
Still TX and RX OK but channel 1, for example is channel 24.
Nothing feels hot and no caps look distressed but that's as far as the investigations have gone so far.....
So any ideas or help please?
The Collector
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Re: Maxcom 30e random frequency

Post by The Collector »

This is well above my level of expertise, so all I can think of is a solder joint on the board or on a component may be opening up near the channel selector stuff as it expands as it warms up??? Perhaps just remelt all the solder joints you can to try and rule them out.

If it's a crack in the tracks etc then that may be harder to find with a soldering iron and definitely beyond me ;)
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CaptainKirk
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Re: Maxcom 30e random frequency

Post by CaptainKirk »

Is it an original Maxcom 30E or the MX30 stickered Danita 640 which is a converted CEPT radio?
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Otter
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Re: Maxcom 30e random frequency

Post by Otter »

If there are no mods I would think it's the PLL going faulty. I don't know the radio though. The schematic I have shows an LC7136/7137 PLL and if that's your radio it reall can only be the PLL or (nuch) less likely the channel switch.
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14CS06
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Re: Maxcom 30e random frequency

Post by 14CS06 »

Hello

Is this :?:

@+
Claude
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ChubbyChops
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Re: Maxcom 30e random frequency

Post by ChubbyChops »

Hi guys, yes it's the 30e exactly as Claude has posted.
My suspicions were around a blown data line in the PLL to Otter.
I guess I need to swap it out although there's no evidence of foul play to bugger it up.
ChubbyChops
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Re: Maxcom 30e random frequency

Post by ChubbyChops »

Otter wrote: 23 Feb 2022, 19:20 If there are no mods I would think it's the PLL going faulty.
Confirmed and fixed :thumbup:
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Re: Maxcom 30e random frequency

Post by CaptainKirk »

Nice one 👍
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Re: Maxcom 30e random frequency

Post by The Collector »

Well done that man. Another radio saved from the scrap heap :)
ChubbyChops
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Re: Maxcom 30e random frequency

Post by ChubbyChops »

The Collector wrote: 25 Feb 2022, 19:45 Well done that man. Another radio saved from the scrap heap :)
I'd never scrap anything with a pulse :lol:
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Re: Maxcom 30e random frequency

Post by The Collector »

ChubbyChops wrote: 26 Feb 2022, 13:44
The Collector wrote: 25 Feb 2022, 19:45 Well done that man. Another radio saved from the scrap heap :)
I'd never scrap anything with a pulse :lol:
I've got this Fidelity 1000 that needs looking at.... ;)
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Re: Maxcom 30e random frequency

Post by ChubbyChops »

I've just revived one of those today.
Had no TX due to a burned out resistor in the output stage.
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