Sunday, January 24, 2010

PFR3A - Group 2 roadblock

I am not having much success with getting the receiver working in the PFR3A and I've been hitting my head against the wall trying to figure it out. Well, maybe I should rephrase that. I think the receiver is technically working; but is very, very deaf.

I can hear background and white noise in the headphones; but when I hook up an antenna, there is noting there that says, "Yep, this is 40 Meters.".

I have rewound and reinstalled both L1 and T1. Not to pat myself on the back; but I've wound enough toroids and transformers to know that I didn't totally screw them up. I have gone over parts placement and values of components; and unless I am totally blind, everything looks Kosher.

The audio stages work fine. I can hear paddle sidetone and the "beeps" when the actuator switches are pressed - and that's about it. When I press pins 4 and 5 of U2, I can hear 60 cycle hum; so Q4, the mute switch, is not shorted out. Interestingly, when I touch pin 6 of U2 with a dental pick or the tip of my tweezers, I can what sounds like shortwave broadcast in the earphones, so it seems like something is working.

I am beginning to wonder if perhaps the DDS might not be working? I have posted a message to the PFR3 Yahoo group. Hopefully, someone else has been through a similar situation and can shed some light on it for me.

73 de Larry W2LJ

1 comment:

  1. If you have a general coverage radio you could tune to the local oscillator frequency and see if you can hear it. That should tell you if the DDS is working or not.