Grant PC-409AC (made 1980) help please

[cb4ever104]

.....so if its good enough for them lol

[dt307]

I got some 945`s with the correct pin out and 733`s and replaced all TR21 to TR27 and saw some improvement and much less "white noise" on transmit but audio was still low and slightly distorted, I replaced the 458 (TR43) beside the audio chip with a 945 and swapped out C46 from a parts rig (links TR43 to TR21), swapping C46 made an improvement on the audio level to a receiver but it is still slightly distorted, I aligned the PLL section and TX this made another slight improvement but receive now is off frequency a bit ?? I will align that once I get my AF genny sorted.
So I still have the problem albeit much better than it was, I think I will replace the other green caps in the audio path as changing C46 did make a fair difference, what type of caps are they ? green dipped rectangle shaped are they poly, ceramic or tants ?

the green caps Polyester Capacitor polly film

[Otter]

I think I will replace the other green caps in the audio path as changing C46 did make a fair difference, what type of caps are they ? green dipped rectangle shaped are they poly, ceramic or tants ?

They're polypropylene caps, but I have never heard of one going wrong. Ever. Since 1980. Not a single one.

[GT390]

I think I will replace the other green caps in the audio path as changing C46 did make a fair difference, what type of caps are they ? green dipped rectangle shaped are they poly, ceramic or tants ?

They're polypropylene caps, but I have never heard of one going wrong. Ever. Since 1980. Not a single one.

I thought too that they were pretty bulletproof and the one I replaced c46 tests OK as far as I can test it. It's got me wondering now why it made a fair difference changing it. I have ordered up some new poly films anyway.

[GT390]

sorry been mental here with new grandson some 711 in the post bro

Chris can you PM your paypal email and I will send you a thank-you

Thank-you to all who helped get to the bottom of this, the fault was electrolytic C191 right at the band selector switch....installed wrong polarity..duh


All working fine now, thinking back I must have only made contacts on FM after installing the new caps and FM is on a separate board on this early set

thanks again
Robert

[Lwc407]

help my -pc-409ac has had xtra chans 26mhz plus 5kc shift and 27mhz has bean added but the clarifier shists all the time how do i lock it to 12 o clock and wind the power down to 4 wts so it can have a 100wts amp on it. and i want to add fm to it as well.

pls any help would be good

73's lwc407 nz

[Tech2]

Best advice would be to send it to Nick, Black Spirit.
You can contact him via the forum.

[cb4ever104]

Best advice would be to send it to Nick, Black Spirit.
You can contact him via the forum.

The guy's callsign is "nz" , so I figure he's in New Zealand . If he is then Nick might not be his best option .