RX tubes in HW-101

[Marten T Beels]

Thanks to all those who responded.  My manual lists 6146, so that's what I'll
go with.

Ed, perhaps I was looking at the tube socket of the 6EV5 from the wrong end, in
which case it would be pin 2 that has been cut, and not pin 6.  That would make
more sense.

Marten
KC8HZM

Quoting ma.locksmith at juno.com:

> An interesting point...
>
> The schematic for the HW-101 that I have does show the V10 and V11 as
> 6HS6, BUT in the area where the filament string is shown, V10 and V11 are
> listed as 6AU6.
>
> The set uses a specially balanced filament string so that it can run six
> volt tubes from 12 volts.  This means the current through each half must
> (should) be identical.
>
> Both of these are sharp cutoff pentodes with the same (7BK) basing.  The
> 6HS6 appears to have a higher transconductance.
>
> The 6HS6 requires 450 milliamperes of filament current but the 6AU6 only
> requires 300.  This does make a difference in the filament balancing.
>
> The 6EV5 is a sharp cutoff Tetrode, not a pentode and the basing is
> different (7EW).  Besides the filament current only requiring 200
> milliamperes, I see there are two connections to the cathode, pins 2 and
> 7, while the other two have the cathode only on pin 7.  Pin 6 is the
> connection to the screen grid.  I can understand if pin 2 were cut, but
> not pin 6.
>
> While they are all used as RF amplifiers, I don't know why one would
> select one over the other for this application.
>
> Ed
> K1ZOK
>
> On Mon, 23 Jun 2003 23:26:05 -0500 Marten T Beels <martentb at GOSHEN.EDU>
> writes:
> > Hello all, this is my first post to the list, so I guess it will do
> > double duty
> > as an introduction.  I have been using a HW-101 as my first HF
> > transciever
> > since 1999 and only recently began having trouble with it.  First
> > off, I think
> > that I blew the finals, only 5 watts RF out.  But that is easy
> > enough to
> > replace.  The hard part is deciding 6146, 6146A, 6146B, 6146W, or
> > 6293.  But
> > there is a lot of discussion in the archives that I can look
> > through.
> >
> > My main question is this: V10 and V11 are listed as being 6HS6
> > tubes, and
> > looking through the archives, there is much discussion of replacing
> > them with
> > 6AU6 tubes.  However, I found 6EV5 tubes installed.  Furthermore,
> > pin 6 has
> > been cutoff from each tube.
> >
> > I wonder if my HW-101 has been modified to use the 6EV5 tubes or is
> > it a direct
> > replacement?  (sans removing a pin)  How similar are the 6EV5 and
> > 6HS6 tubes?
> >
> > Marten
> >
> >
>




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