Re: {Collins} Oscillation on 30L-1



Mike, Will do. Thank you for the advise.

Carlos.



> On Oct 18, 2017, at 3:53 PM, Michael Student <w7ms20wpm@xxxxxxxxxxxxx> wrote:
> 
> Carlos, check the compression nut on the  variable tune capacitor rotor shaft. I repaired a hanger queen that was heavily hamstered and determined that the original issue was a poor RF ground on the rotor shaft  that led to many chop and go repair attempts by a former molester.
>  
> Good Luck, Mike W7MS
>  
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>  
> From: Carlos Pechiar via Collins <mailto:collins@xxxxxxxxxxxxx>
> Sent: Wednesday, October 18, 2017 11:24 AM
> To: Leigh Sedgwick <mailto:bipi@xxxxxxxxxxx>
> Cc: collins@xxxxxxxxxxxxx <mailto:collins@xxxxxxxxxxxxx>
> Subject: Re: {Collins} Oscillation on 30L-1
>  
> Mike,
>  
> Thanks for your prompt reply. Sorry for the ignorance. I am not aware of the source you mention for the article (Signal). I guess it’s a magazine or publication but I cannot get any consistent info online.
>  
> Can you advise?
>  
> Thanks again.
>  
> Carlos
>  
>  
> > On Oct 18, 2017, at 2:43 PM, Leigh Sedgwick <bipi@xxxxxxxxxxx <mailto:bipi@xxxxxxxxxxx>> wrote:
> >
> > Carlos,
> >
> > See the excellent article written by Don Jones on this subject and how to correct it in the Signal, Q4 2013.
> >
> > Good Luck
> >
> > de Mike
> > K7PI
> >
> > -----Original Message-----
> > From: Collins [mailto:collins-bounces+bipi=comcast.net@xxxxxxxxxxxxx <mailto:collins-bounces+bipi=comcast.net@xxxxxxxxxxxxx>] On Behalf Of Carlos Pechiar via Collins
> > Sent: Wednesday, October 18, 2017 10:03
> > To: collins@xxxxxxxxxxxxx <mailto:collins@xxxxxxxxxxxxx>
> > Subject: {Collins} Oscillation on 30L-1
> >
> > Hello everyone.
> >
> > I am fixing a 30L-1 for the Club which was out of service and that we do not know the history behind it. It has 811 tubes that are mid-life but the four measure the same. I replaced the original power supply with the replacement kit found online. No problem with that. I also replaced the chokes on the plates of the tubes that were overheated and their resistors cracked.
> >
> > First tests went fine but suddenly, in the 20m band, when keyed down, an oscillation was trigged drawing about 1 amp on the plate current and overheating the new chokes.
> >
> > I have seen this behavior before in other units but they were repaired by other people. I also heard that there is some “fix” for that or, a reason for that to happen.
> >
> > Al tests were performed on a dummy load.
> >
> > I’ll appreciate help.
> >
> > Thank you for your time,
> >
> > Carlos
> > CX6BT.
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