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Old 04-22-2017, 11:50 AM
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Default Icom F221S Poor Receive Sensitivity

I recently sold a customer of mine 10 working Icom F221S UHF mobiles. 2 months later he said a bunch of them weren't working right. He gave me 5 of the radios back, all of which now have very poor receive sensitity. About 1K microvolts. They transmit fine. Any idea what may have happened and what to look for? Thanks in advance.
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Old 04-23-2017, 1:47 AM
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What was the install like?
If the antennas were too close to another transmitting antenna, it's possible to get so much RF into the receive side of the radio that it'll burn out components and do exactly what you are seeing.
The fact that they worked when you installed them (you did test them, right?) and then 2 months later they are doing this would suggest something like high RF overloading.
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Old 04-23-2017, 6:16 AM
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I did not do the installs. The radios were working fine when I sold them.
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Old 05-29-2017, 3:52 PM
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I am (slowly) going through a fleet of F1821's I sold back in 2008. Most are fine, but a few are stone deaf (-90db vs -120db). I have seen the same isue with other older chassis.

Simple software alignment takes 15 minutes has made them all happy campers.
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Old 05-29-2017, 4:31 PM
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Quote:
Originally Posted by jeatock View Post
I am (slowly) going through a fleet of F1821's I sold back in 2008. Most are fine, but a few are stone deaf (-90db vs -120db). I have seen the same isue with other older chassis.

Simple software alignment takes 15 minutes has made them all happy campers.
Yeah, I tried aligning mine. No dice. Even tried tuning the VCO to no avail.
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Old 05-29-2017, 7:20 PM
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Willing to bet it's a defective ceramic filter. Very common on those (they had a bad run of them that affected many brands) and does exactly what you describe
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Old 05-29-2017, 9:16 PM
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Willing to bet it's a defective ceramic filter. Very common on those (they had a bad run of them that affected many brands) and does exactly what you describe
Looks like you may be right. I tested 2 radios so far and both had bad filters. Gonna order a bunch of them tomorrow. Thanks for your help.
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Old 05-30-2017, 8:34 AM
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Quote:
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Looks like you may be right. I tested 2 radios so far and both had bad filters. Gonna order a bunch of them tomorrow. Thanks for your help.
Good to hear you found it. I have seen the same, especially in the F-X21-series
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