M1225 UHF audio issue

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mmb
Posts: 34
Joined: Wed Sep 07, 2005 3:40 pm

M1225 UHF audio issue

Post by mmb »

I have an M1225 UHF 20 channel unit. I've had it about 4 years but recently it's acting up. When first turned on the receive audio is very weak & fuzzy. After it's been on for a few minutes it's totally fine. I've not seen any problems on the transmit side so far, only receive?

Charles
KI4DCR
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perthcom
Posts: 280
Joined: Sat Dec 08, 2001 4:00 pm

Post by perthcom »

Although i've never seen that problem in an M1225, sounds like a bad capacitor in the audio amplifier.

Get yourself a 'scope and just follow the audio path till you find the offending component, (course you can only do this while its acting up!)

8)
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Will
Posts: 6823
Joined: Tue Sep 04, 2001 4:00 pm

Post by Will »

Leaking capacitor. Same problem on Maxtrac, Radius and GM series (mobile) radios.

Look for a 33uf cap in the input to the first audio stage filter op-amp. form the discriminator output. Replace with a low leakage 10uf at 25 v.

Also see "Maxtrac, Slow Warm-up". Use the Search button.
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