Magnum Deltaforce Low Output On SSB.

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astradyne
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Magnum Deltaforce Low Output On SSB.

Post by astradyne » 19 Nov 2017, 21:03

I have the above radio and all is fine on AM/FM. 25W output on full power and great TX audio. On SSB however there's only around 6W output on a whistle, but still with great TX audio.

Now this can't be a driver/outputs issue as they're providing exactly what they should on AM/FM (This is the 2 × 1969 version) and the RF power is variable. I've noticed that the ALC preset doesn't actually do anything. It's the same 6W output wherever it's set to. I've checked the back of the PUB and nothing's been added to bridge over it (like in the French Jackson's etc). Next step, when I find my meter, is testing the output regulator.

Does anyone have any ideas outside of that?

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ch25
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Re: Magnum Deltaforce Low Output On SSB.

Post by ch25 » 20 Nov 2017, 18:59

What is voltage on final(s) collectors on SSB TX?
Do you have PEP meter, dual tone generator, scope?
If alc pot is not responding, first thing is to get it working again.
Chris

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Re: Magnum Deltaforce Low Output On SSB.

Post by astradyne » 21 Nov 2017, 11:38

Hi Chris.

The voltage on the collectors of both 1969's is 12.6V.

I don't have any of the equipment you mentioned. Too technical for me.
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Re: Magnum Deltaforce Low Output On SSB.

Post by ch25 » 21 Nov 2017, 12:53

Remove Q174 to check if disabled ALC will change anything.
Check D189 and Q141.
Check bias current for driver and final(s).
Come back with results.
Chris

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Re: Magnum Deltaforce Low Output On SSB.

Post by astradyne » 21 Nov 2017, 13:18

Will do Chris.
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Re: Magnum Deltaforce Low Output On SSB.

Post by cb4ever104 » 21 Nov 2017, 14:30

ch25 wrote:
20 Nov 2017, 18:59
If alc pot is not responding, first thing is to get it working again.
I second that . People will do all sorts to max out the ALC , including removing components etc. I'd check that part of the circuit first and get it working .

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Re: Magnum Deltaforce Low Output On SSB.

Post by astradyne » 21 Nov 2017, 15:11

Ok. Removed Q174 and no difference whatsoever.
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Re: Magnum Deltaforce Low Output On SSB.

Post by ch25 » 21 Nov 2017, 16:56

Let's go further. Remove Q142 and check SSB power. What is current consumption on TX btw?

speeddemon

Re: Magnum Deltaforce Low Output On SSB.

Post by speeddemon » 21 Nov 2017, 23:05

Hi astradyne I would suggest that you look at the schematic and go tru the radio slowly Check all electronic components to be there and in spec/working and function properly before removing anything :ugeek: . Cheers n 73's

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