Spectra microphonic on RX

[m109a3]

Ok I have checked the " bad connections inside checked rx board grounds and looked for any loose screws on the boards. what can make this spectra microphonic
as in I have the radio on and wile in rx I tap lightly on the case and i hear it in the speaker kinda like a bell ?

thanks for any insight.
VHF Dash unit with 11 Segment display

[m109a3]

I have one error to correct in my post the head is a A5 8 VFD not an 11VFD
might there be a bad cap causing micro-phonic noise on RX
Thanks

[WB6DGN]

Is it microphonic when receiving a signal or all the time? The Spectra I have uses those little blue Murata IF filters. That is a common problem with those. If yours uses those filters, try tapping gently on the filter case. The tapping sound should get quite loud. The VCO can also cause the problem when receiving a signal and finding the defective component or connection can be an exercise in patience, to say the least. I don't have enough experience with Spectras to know if there's a common cause for it or not. I'm sure others will have more info. Good luck,
Tom

[m109a3]

Yep its just during RX the radio clears up when there is no rx going on
I'm going back in for another look thanks

[m109a3]

ok well i changed the RX board and well its great! .
I still have no idea what is not working. I hope to trouble shoot this " bad " board in another radio and learn how to service it.
has anyone els had this happen ?

[Bill_G]

Is it microphonic when receiving a signal or all the time? The Spectra I have uses those little blue Murata IF filters. That is a common problem with those. If yours uses those filters, try tapping gently on the filter case. The tapping sound should get quite loud. The VCO can also cause the problem when receiving a signal and finding the defective component or connection can be an exercise in patience, to say the least. I don't have enough experience with Spectras to know if there's a common cause for it or not. I'm sure others will have more info. Good luck,
Tom

Sounds like you nailed it. (high five)