Re: {Collins} Oscillation on 30L-1



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
Sent: Wednesday, October 18, 2017 11:24 AM
To: Leigh Sedgwick
Cc: 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> 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] On Behalf Of Carlos Pechiar via Collins
> Sent: Wednesday, October 18, 2017 10:03
> To: 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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