On Oct 4, 2005, at 8:35 AM, Frank N. Haas wrote:
>
> Fellow AMPers:
>
> I just took delivery of 3 well used 3CX400A7/8874 ceramic power
> triodes. I
> bought them as spares for my recently purchased Alpha 78 amp.
>
> All 3 tubes are rather tarnished with many dark spots and no shine
> whatsoever.
>
> I want to test these tubes in my Alpha 78 to insure that all 3 work.
>
> Should I clean them before I install them??? If so, what is the
> recommended
> cleaning technique for these tubes?
Frank
Immerse them in diluted ammonia overnight - then polish them with Bon
Ami® cleanser, rinse and dry. However, the 8874s should first be
high-potted to see if the gold-plating on the grid has sputtered.
>
> Are common "household" products like TARN-X, NEVR-DULL, BRASSO or the
> like
> appropriate??
These are aggressive cleaners.
>
> Is it even important that the tubes be clean?
>
For the Funderberg gold-sputter test, shiny clean matters not.
http://www.somis.org/Goldmeltballs.html
> 73,
>
> Frank N. Haas KB4T
> Florida
>
>
Richard L. Measures, AG6K, 805.386.3734. www.somis.org
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