[Collins] {Collins} 75A-4 dead on 40 mtrs only

[Michael Marx]

		Dave
On 3 separate occasions I had a band go dead on a 75A4. All 3 times it was the mica padder across the crystal oscillator coil.  Do the obvious things first like cleaning switches, etc.  But if its still dead I’d replace that mica
73Mike. WB0SND 
		
		

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On Mon, Apr 23, 2018 at 3:49 PM -0500, "rls19 via Collins" <collins at listserve.com> wrote:










Dave,

The first thing I would do is clean the band switch. 15 meters went dead on my A-4 and that was what fixed it.

73,
Bob AD3K

> On Apr 23, 2018, at 8:20 AM, David Propper  wrote:
> 
> HI all,
> 
> Just finished re-capping my SN1135 75A-4 and it was working beautifully for 2 days. Last night, 40 mtrs just went absolutely dead. Receive sensitivity is fine on all other bands. I pulled all the crystals just to be sure it wasn’t an intermittent contact. Looking at the schematic, I suspect that possibly C10- a 300mmf mica padding capacitor across the first stage coil might have gone south.  This cap (postage stamp red mica) does have a blister on it at one end.
> 
> Any other thoughts / recommendations as to the culprit ? I probably won’t have a chance to work on the receiver until later this week.
> 
> Any help would be appreciated.
> 
> Thanks and 73,
> Dave, K2DP
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