Quote:
Originally Posted by G0HZU_JMR
The 10M08AA is a crystal filter and this would have been used in place of CF101 to improve the 'bleedover' performance of the radio. However, I wouldn't recommend the 10M08AA as it is too narrow and typically gives a harsh sound to the receiver. The 10M15A is a better filter. It looks the same but is wider and doesn't give the harsh sound of the 10M08AA.
The original radio would have used a ceramic filter here at CF101 and this was followed by the MC3357 mixer/FM chip. The ceramic filter was very wide and gave overload/bleedover issues in the MC3357 IF chip, especially when used on UK FM CB when it was busy. My advice would be to check to see if there is a 10M15A filter fitted here or the original ceramic filter.
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Hello again, Jeremy.
I got around to opening the Icom this morning, and there's a 10M15AA filter in position CF101 so that's handy.
There's a strange little enclosed red box on the rear inside of the chassis, and I've never seen anything like this before. It connects to the + pin of the power socket, and the remaining terminal goes to an inductor near the usual + entry point on the PCB - so maybe it's a fuse or suppressor of some sort?
There's also a home brew board hanging & uninsulated, and it consists of 2 x HEF40088PB IC's.
I've not really got around to properly describing the fault with the Harvard 407, but when I get chance to, I'll publish another thread so as to avoid detailing this one.
Here are some images of the Icom 1050 guts....