Batboard

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

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!)

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.