Re: {Collins} More on the 30S-1 saga

First on my list would be to verify that the metering circuits (grid and screen at least) are reading correctly. This would include, but not limited to, measuring meter shunts and series resistances and verifying that the meter movement is correct and hasn't been swapped out with an incorrect movement. Remember, hammy hambone knows no bounds! Look for further 'mis-wiring'. As a quick check, remove tube and use an external low voltage power supply with suitable loads to simulate expected current draws and see what the meter indicates.

Jay W1VD

----- Original Message ----- From: "Roy Morgan" <k1lky68@xxxxxxxxx>
To: "Lyke That" <lykethat@xxxxxxxxx>; "collins" <collins@xxxxxxxxxxxxx>
Sent: Thursday, November 13, 2014 11:42 PM
Subject: Re: {Collins} More on the 30S-1 saga

On Nov 13, 2014, at 10:29 PM, Lyke That <lykethat@xxxxxxxxx> wrote:

So here is the question.  What do I check next on the Second amp?

Others will have suggestions based on way more experience than I have but here are a some ideas:

The grid bias may not be getting to the actual tube pin. Same for screen voltage. The tube socket my be causing trouble. Check socket carefully, with attention to contact fingers.

There may be a bypass capacitor IN the socket. If it’s flaky or leaking or such, it may be causing trouble.

There may be parasitics happening. Test with a grid dipper in detector mode. Get advice as to possible or likely frequencies. BE VERY CAREFUL around live circuits. See W8JI website for some ideas.

What you think are ground connections or bypass caps may have failed. Loosen and tighten all suspect ground and shielding points and hardware.

Borrow the Whouff Hong from ARRL headquarters and wave it over the amp, all the while incanting the names Eitel and McCollouch.

Bring the working amp as close as possible to the sick one in hopes the good vibes move over and cure the mystery.

Lastly, when you do solve it, let us all know!



Roy Morgan
K1LKY Since 1958

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