Nautical VHF radio from Raymarine type 49e, Tx ok but no Rx. Understand a possible cause might be linked to bad ceramic filters I've located two ceramic filters marked "CQ M50FW". Need help to find any information for replacement, as manufacturer, data sheet, possible replacements type, etc. Thanks
These?
Peter Wieck Melrose Park, PA
Any coloured dots on them? Coincidence I just replaced a 10.7M one this afternoon, as easier than hooking up an RF oscillator to test if failed FM receiver. Unfortunately not the silver migration, ohmic problem ,something else around an LA1186 FM front end, all DC are correct by the schematic.
Why think the ceramic filters are bad?
Inject a signal into that IF, see if it gets past the filters. To double check, inject after the filters.
Assuming it's old enough to use crystals, why not wonder if the local oscillator crystal (or any second conversion crystal, if there is one) is bad or not oscillating? Have you even checked to make sure there is a crystal for the first oscillator in the receiver?
Michael
Yep. Junk ceramic filters are an all too common problem. I saw an ICOM IC-M411 marine radio with an identical filter problem. It was fixed under the warranty, so I didn't a chance to play with it. I'm not sure what caused the problem but as I recall, it happened very quickly after the initial OOB (out of box) experience. Everything was fine for a few days, then nothing. Sound familiar?
The filter is extremely common and you should have no trouble finding one: Maybe stock up? 20 pcs for $20:
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
Jeff, while de soldering one of them, the case fall apart and find green sign of oxidation inside, as described in the above link.
This is a sort of blind repair (no schematic and no RF equipment).
Is the LTM 450DW a correct replacement? Dino
In my case it was failed 20 yearold solder at one of those large wire
1.5 turn air cored inductors, presumably from heatsinking of the original PbSn soldering
The Icom radio I saw did not show any signs of corrosion. However, the cover was loose and wiggling it caused the signal to rise and fall dramatically.
The Raymarine RAY49E is a fairly new product and should still be under warranty. Have you checked?
Sorry, I couldn't find any schematics.
I think it's the same part. Finding specs on the filter has not been very productive, so I can't compare data sheets.
I provided an eBay part that looks like an exact replacement: Note that the listing shows that it's used in a wide variety of low end radios. Good enough methinks.
More:
The only problem is that there's no guarantee that the replacement part will be any better quality than the original. You might want to buy one or two from different vendors.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
I'll follows your suggestion to source parts from different supplier. Ciao, Dino
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