Re: The Drake 2B and its Frequency Spread Limitations
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Silicon diodes have different internal resistances and voltage drops than rectifier vacuum tubes.
Before replacing the vacuum tubes I would first model the power suppy to see how it would perform after the mod.
DUNCAN AMPS - PSUD2 PSU Modeling Software
QUOTE PSU Designer II is designed to help you with the design of simple linear (unregulated) mains power supplies, as often found in tube amplifiers. UNQUOTE
73 de Andrew/N5ASE
I would not recommend replacing the 6X4 with silicon diodes. Leave
the 6X4 in place.
Just what does one expect to accomplish by substituting silicon
diodes in place of the
6X4 rectifier tube? What harm to your 2B receiver have you the owner
found that
occurs by leaving the 6X4 tube in place?
The formula for calculating the crystal frequencies is found on page
10 in the 2B manual.
A single crystal can provide 2 different frequency ranges. This is
explained in the 2B manual
on page 10.
I have two Drake 2B receivers. The calibrator is not as good as one
would expect it to be.
It's a little weak on some bands but stronger on other bands. I
found this to be true on
both on my 2B receiver. Both of my 2B receiver have the 2AC plug in
calibrators.
I recommend finding and adding the Drake 2AQ Multiplier. It adds
quite a bit of selectivity to the
2B receiver.
73
Mike W5RKL
On 5/20/25 7:09 PM, Steve Wedge, W1ES/4
via wrote:
My
first 1-A came with diodes replacing the 6X4,? At the time, it
was an easy mod that was popular at a time when people wanted to
replace tubes.? I removed the diodes and bought a NOS 6X4 off
eBay for about $4 + shipping.
If
not properly compensated, using solid state diodes in place? of
a tube can raise the voltage on the plate supply.? In the case
of the 1-A, Drake used lots of taps to provide various voltages
instead of just perhaps using two different plate voltages like
the R-4(any).? The highest voltages were near 200V before I put
the tube back in.
Steve Wedge, W1ES
Time flies like an arrow.? Fruit flies like a banana.
Sent with secure email.
On Tuesday, May 20th, 2025 at 6:32
PM, Richard W2ONE via
<cowboyhat@...> wrote:
Hey Gary,
?
Here are some more pictures of my cabinet.? Yes, a
previous owner stuck a Heathkit 100 kc Calibrator in place
of the Drake 100 kc Calibrator.? A previous owner also
replaced the 6X4 tube with two diodes.? I believe I read
somewhere that this is a hack on the 2B, but I do not
remember if the hack was an improvement over the use of the
6X4 tube or as a substitute if the tube cannot be located.?
I would appreciate any words of wisdom that anyone has on
these two situations (my Heathkit calibrator and the diode
replacement of the 6X4 tube).
?
Other pictures showing the crystals that have been
installed and the bottom of the chasis.
?
Richard
W2ONE
?
?
?
?
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