[R-390] 6BJ6/6BH6 sub

[David Wise]

Affirmative, strong-signal performance will be suboptimal, with
increased vulnerability to overload and cross-modulation.
If it takes less AGC than normal to achieve a given gain (the
case with a 6BH6 sub), then the front end is running hotter
than intended, which means it takes less signal to drive them positive.
Your carrier meter will also read low.

The "3D" in your copy of my old post is the tilde character, meaning "approximately".
Most of those tubes can't be compared apples-to-apples from the specs,
as some are tabulated for a given plate current, others for a given
transconductance.  (It would be possible to get closer with many
models of transconductance tube tester.)  I only meant to list all the ones
I could find that would operate, with no implication that they would do well.
It seems odd to me that the 6DC6 is less than abundant; it was made for TV's.

73,
Dave

> -----Original Message-----
> From: r-390-bounces at mailman.qth.net
> [mailto:r-390-bounces at mailman.qth.net]On Behalf Of n4buq at knology.net
> Sent: Tuesday, February 28, 2006 11:52 AM
> To: r-390 at mailman.qth.net
> Subject: Re: [R-390] 6BJ6/6BH6 sub
> 
> 
> Okay.  I had them reversed.  I thought that didn't make 
> sense, but now it 
> does.
> 
> Thanks!
> 
> Barry
> 
> On Tue, 28 Feb 2006 14:23:37 -0500, "Tim  Shoppa" <tshoppa at wmata.com> 
> wrote :
> 
> > > Okay, now it's time to educate me on this issue.  If the 6BH6 is a
> > remote
> > > cutoff tube, then it won't go into cutoff as "early" as the sharp
> > cutoff
> > > 6BJ6, right?
> > 
> > Other way around: 6BJ6 is remote cutoff, 6BH6 is sharp cutoff.
> > 
> > The 6BJ6 was the original IF tube. 6BH6 is the sub.
> > 
> > >  If that's the case, then why will you see distortion on strong 
> > > signals with the remote cutoff tube?
> > 
> > Actually either will distort with very strong signals. And when
> > you're subbing around it's likely that biases etc will be quite
> > unoptimal for critical use.
> > 
> > Tim.
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