[Boatanchors] General question on substitutions

[Peter Markavage]

Personally, I generally view "substitutions", "can be substituted", might
work if substituted", etc. as only a last resort, finger crossing, etc.
type activity. 12BY7's are not rare, All the Kenwood hybrid type rigs of
the 70's used them and so did Yaesu. Tektronix used them in many of their
scopes. That famous site that we not to speak of, always seems to have
them listed. Some of the RCA 12BY7 boxes I have, has printed on the end,
12BY7/12BV7/12DQ7.

Pete, wa2cwa

On Wed, 17 Jan 2007 18:23:26 +0000 "Eugene Hertz" <ehertz at tcaf.org>
writes:
> I am investigating a problem in my central electronics 100V 
> transmitter. I *think* the problem is with the first mixer which is 
> a 12BY7. I began looking to get this tube and noticed there are 
> subtitutions available. Other than the 12BY7A which is a "slow 
> start" version, some websites list substitutions as 12BV7, 12DQ7, 
> 12GN7. However not all websites list all of these as subsitutes for 
> each other.
> 
> The GE datasheet for the 12BV7 is the only sheet that directly 
> mentions the 12BY7 saying "In application and characteristics it is 
> related to the 12BY7" 
> 
> Some sites like NJ7P list a "preferred" substitute as the 12DQ7 and 
> a general substitute (not preferred) as the 12GN7 but does not 
> mention the 12BV7 (again which is mentioned as a "related" tube in 
> the GE datasheet.
> 
> So what does it all mean? Am I making much ado about nothing here? 
> Do I just pick whichever I can find in my tube spares and try it? If 
> it works leave well enough alone? Is it possible that one of these 
> is lower noise than the others and could be beneficial? Or any other 
> benefit? (i.e. Oh yes, people stopped using the 12BY7 in favor of 
> the 12xx7 long ago because of its superior properties...)
> 
> What sayeth you all tube experts?
> Eugene
> 
> 
> 
> 
> 
> 
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