Wanted, Diodes
 

I am looking for a few (10) diodes 1N270...It is a germanium and used
in Double Balanced mixers in SSB generation..Most suppliers have a $25
to $50 min order and I don`t care for that.. thanks Harold W4PQW

Wanted, Diodes
 

"mrhaney" wrote in message
...
I am looking for a few (10) diodes 1N270...It is a germanium and used
in Double Balanced mixers in SSB generation..Most suppliers have a $25
to $50 min order and I don`t care for that.. thanks Harold W4PQW

Hi Harold. I can supply your needs, but for info, I have never. in a lot of
years, called on MiniCircuits Labs (MO) for a small order and not have them
waive the minimum order charge if needed. VERY nice folks to work with and
they make better balanced mixers than you will. They have some black magic
in their ferrite department.

W4ZCB

Wanted, Diodes
 

"mrhaney" wrote in message
...
I am looking for a few (10) diodes 1N270...It is a germanium and used
in Double Balanced mixers in SSB generation..Most suppliers have a $25
to $50 min order and I don`t care for that.. thanks Harold W4PQW

Have you tried Dans Small Parts? Are hot carrier diodes
an acceptable substitute for that application?

73

Pete

Wanted, Diodes
 

On Aug 17, 9:12*pm, mrhaney wrote:
I am looking for a few (10) diodes 1N270...It is a germanium and used
in Double Balanced mixers in SSB generation..Most suppliers have a $25
to $50 min order and I don`t care for that.. thanks * Harold W4PQW

Are you trying to reproduce something from a 60's handbook? I remember
them speccing 1N270's but that's because those were the parts people
had in the junkboxes back then. There is nothing at all magic about
germanium here. The silicon diodes will require slightly more drive
voltage to switch but that's not a big deal as you always drive them
way into saturation anyway.

NTE109 is the ECT/NTE number for a their medium-voltage germanium
replacement, officially listed in the NTE sub book, and Mouser and
maybe even your local radio/TV repairman would have some. Mouser has
no minimum order.

You will have much better luck using 1N914's or 1N4148's or even
better a real matched DBM from Minicircuits et al. "Experimental
Methods in RF Design" has a lot of good scoop on mixers that goes way
beyond anything in a 60's ARRL handbook.

Tim N3QE

Wanted, Diodes
 

On Aug 17, 9:12 pm, mrhaney wrote:
I am looking for a few (10) diodes 1N270...It is a germanium and used
in Double Balanced mixers in SSB generation..Most suppliers have a $25
to $50 min order and I don`t care for that.. thanks Harold W4PQW

Hey Harold:

Try your luck with this guy:

http://www.angelfire.com/electronic2/index1/index.html

takes paypal has tonnes of them in stock and only charges

$3.95 for shipping and handling for an order like yours

The shipping cost more than the parts but there's no

minimum order.

73 OM

N8ZU

Wanted, Diodes
 

On Aug 17, 6:12*pm, mrhaney wrote:
I am looking for a few (10) diodes 1N270...It is a germanium and used
in Double Balanced mixers in SSB generation..Most suppliers have a $25
to $50 min order and I don`t care for that.. thanks * Harold W4PQW

So after all that, any hints on what the original project was? Even
in the 1970s people were speccing matched silicon diodes (e.g. 1N914)
or hot carrier diodes (e.g. 5082-2800) for mixers.

Laura Halliday VE7LDH "Non sequitur. Your ACKS are
Grid: CN89mg uncoordinated."
ICBM: 49 16.05 N 122 56.92 W - Nomad the Network Engineer

Wanted, Diodes
 

On Aug 23, 3:39*pm, laura halliday wrote:
On Aug 17, 6:12*pm, mrhaney wrote:

I am looking for a few (10) diodes 1N270...It is a germanium and used
in Double Balanced mixers in SSB generation..Most suppliers have a $25
to $50 min order and I don`t care for that.. thanks * Harold W4PQW

So after all that, any hints on what the original project was? Even
in the 1970s people were speccing matched silicon diodes (e.g. 1N914)
or hot carrier diodes (e.g. 5082-2800) for mixers.

At least two volumes of "Single Side Band for the Radio Amateur" and
many ARRL handbooks from the 60's show 1N270's used in balanced
mixers.

It was a jellybean of the time, it's odd that someone would not
realize it and slavishly want to use it rather than something more
readily available (and performance-wise far superior) today. Probably
the same guys who insist on carbon-composition resistors everywhere
today too :-).

There are some things that appear in old construction articles that
are worth finding. For example, the BC-453/454/455's tuning capacitors
and drive mechanism are truly superb and I still keep my eyes open for
them today :-).

Tim.

Wanted, Diodes
 

I have 1N34A's... will they do?

Cheers,
__
Gregg

Wanted, Diodes
 

On Aug 25, 6:14 am, Tim Shoppa wrote:
On Aug 23, 3:39 pm, laura halliday wrote:

On Aug 17, 6:12 pm, mrhaney wrote:

I am looking for a few (10) diodes 1N270...It is a germanium and used
in Double Balanced mixers in SSB generation..Most suppliers have a $25
to $50 min order and I don`t care for that.. thanks Harold W4PQW

So after all that, any hints on what the original project was? Even
in the 1970s people were speccing matched silicon diodes (e.g. 1N914)
or hot carrier diodes (e.g. 5082-2800) for mixers.

At least two volumes of "Single Side Band for the Radio Amateur" and
many ARRL handbooks from the 60's show 1N270's used in balanced
mixers.

It was a jellybean of the time, it's odd that someone would not
realize it and slavishly want to use it rather than something more
readily available (and performance-wise far superior) today. Probably
the same guys who insist on carbon-composition resistors everywhere
today too :-).

There are some things that appear in old construction articles that
are worth finding. For example, the BC-453/454/455's tuning capacitors
and drive mechanism are truly superb and I still keep my eyes open for
them today :-).

Tim.

Indeed. I have several old ARRL and RSGB Handbooks and a
number of older references (including Single Sideband for the
Radio Amateur).

You can see the fashions change. At one time the cool part to
use was the 7360 beam deflection mixer tube; at other times the
challenge was to see how many 40673 MOSFETs you could use
in a single radio. Many of these designs are difficult to reproduce
now.

I'll see your BC-455 tuning capacitor and raise you an Eddystone
dial. :-)

You can make nice radios by applying the right technology to
the problem. My recipe for a stable VFO nowadays is a
postage-stamp size surface mount board mummified in bubble
wrap and stuck to the end of a good, solid air variable capacitor.

Laura Halliday VE7LDH "Non sequitur. Your ACKS are
Grid: CN89mg uncoordinated."
ICBM: 49 16.05 N 122 56.92 W - Nomad the Network Engineer

Wanted, Diodes
 

On Aug 26, 11:30*am, laura halliday wrote:
Indeed. I have several old ARRL and RSGB Handbooks and a
number of older references (including Single Sideband for the
Radio Amateur).

You can see the fashions change. At one time the cool part to
use was the 7360 beam deflection mixer tube; at other times the
challenge was to see how many 40673 MOSFETs you could use
in a single radio. Many of these designs are difficult to reproduce
now.

What's amazing is that some of the SSB rigs appearing in the 60's in
the pages of QST use not one, not two, but three 7360's :-).

40673's were also used with wild abandon. If someone wants an honest-
to-goodness 40673 they can pay $15 for a NTE221 in a metal can, but
most experimenters would use a BF998, obviously a different package
but same function.

I'll see your BC-455 tuning capacitor and raise you an Eddystone
dial. :-)

You can make nice radios by applying the right technology to
the problem. My recipe for a stable VFO nowadays is a
postage-stamp size surface mount board mummified in bubble
wrap and stuck to the end of a good, solid air variable capacitor.

The brass-screw-in-a-solenoid is something I just tried in my
reproduction of the MMR-40 and I am very impressed with its stability
and mechanical simplicity as a PTO. A similar but not identical
mechanical design is used in the WA6OTP PTO, I haven't tried it yet.

Tim.

Wanted, Diodes
 

On Aug 26, 10:46 am, Tim Shoppa wrote:
....
The brass-screw-in-a-solenoid is something I just tried in my
reproduction of the MMR-40 and I am very impressed with its stability
and mechanical simplicity as a PTO. A similar but not identical
mechanical design is used in the WA6OTP PTO, I haven't tried it yet.

Tim.

Though not actually PTO if it's a brass screw, right?

Cheers,
Tom

Wanted, Diodes
 

On Aug 26, 2:26*pm, K7ITM wrote:
On Aug 26, 10:46 am, Tim Shoppa wrote:
...

The brass-screw-in-a-solenoid is something I just tried in my
reproduction of the MMR-40 and I am very impressed with its stability
and mechanical simplicity as a PTO. A similar but not identical
mechanical design is used in the WA6OTP PTO, I haven't tried it yet.

Tim.

Though not actually PTO if it's a brass screw, right?

Permeability of brass is slightly less than air, which is why the PTO
goes up in frequency as I screw the brass screw in.

It's not an iron-powder slug (which would go down in frequency as it
enters the solenoid) but it's still a PTO.

If you haven't tried them, I highly encourage you look at the PTO in
the MMR-40 and the WA6OTP PTO. Completely 100% homebrewable and I'm
very happy with the results.

Tim.

Wanted, Diodes
 

On Aug 26, 12:05*pm, Tim Shoppa wrote:
On Aug 26, 2:26*pm, K7ITM wrote:

On Aug 26, 10:46 am, Tim Shoppa wrote:
...

The brass-screw-in-a-solenoid is something I just tried in my
reproduction of the MMR-40 and I am very impressed with its stability
and mechanical simplicity as a PTO. A similar but not identical
mechanical design is used in the WA6OTP PTO, I haven't tried it yet.

Tim.

Though not actually PTO if it's a brass screw, right?

Permeability of brass is slightly less than air, which is why the PTO
goes up in frequency as I screw the brass screw in.

It's not an iron-powder slug (which would go down in frequency as it
enters the solenoid) but it's still a PTO.

If you haven't tried them, I highly encourage you look at the PTO in
the MMR-40 and the WA6OTP PTO. Completely 100% homebrewable and I'm
very happy with the results.

Tim.

Well, I beg to differ with you about the (main) reason the frequency
changes. Consider what happens if you have two coils magnetically
coupled and you monitor the inductance of one while you apply a short
across the other one. Then consider what you'll see on the inductance
meter as you change the coupling between the measured coil and the
shorted one. The references I've been able to find so far suggest the
permeability of brass is slightly higher than that of air, but I
suppose it's a function of the composition of the brass; in any event,
I'd bet that the shorted-turn effect is very much larger than the
permeability effect with respect to changing the inductance of the
oscillator coil.

Cheers,
Tom

Wanted, Diodes
 

On Aug 27, 3:58 pm, K7ITM wrote:
On Aug 26, 12:05 pm, Tim Shoppa wrote:



On Aug 26, 2:26 pm, K7ITM wrote:

On Aug 26, 10:46 am, Tim Shoppa wrote:
...

The brass-screw-in-a-solenoid is something I just tried in my
reproduction of the MMR-40 and I am very impressed with its stability
and mechanical simplicity as a PTO. A similar but not identical
mechanical design is used in the WA6OTP PTO, I haven't tried it yet.

Tim.

Though not actually PTO if it's a brass screw, right?

Permeability of brass is slightly less than air, which is why the PTO
goes up in frequency as I screw the brass screw in.

It's not an iron-powder slug (which would go down in frequency as it
enters the solenoid) but it's still a PTO.

If you haven't tried them, I highly encourage you look at the PTO in
the MMR-40 and the WA6OTP PTO. Completely 100% homebrewable and I'm
very happy with the results.

Tim.

Well, I beg to differ with you about the (main) reason the frequency
changes. Consider what happens if you have two coils magnetically
coupled and you monitor the inductance of one while you apply a short
across the other one. Then consider what you'll see on the inductance
meter as you change the coupling between the measured coil and the
shorted one. The references I've been able to find so far suggest the
permeability of brass is slightly higher than that of air, but I
suppose it's a function of the composition of the brass; in any event,
I'd bet that the shorted-turn effect is very much larger than the
permeability effect with respect to changing the inductance of the
oscillator coil.

Cheers,
Tom

I agree, except Air has no permeability, you can't magnetize air. You
can't magnetize brass. What you have is a proximity detector. aka
metal detector.

73
n8zu

Wanted, Diodes
 

On Aug 28, 7:29*am, raypsi wrote:
On Aug 27, 3:58 pm, K7ITM wrote:
I'd bet that the shorted-turn effect is very much larger than the
permeability effect with respect to changing the inductance of the
oscillator coil.

Cheers,
Tom

I agree, except Air has no permeability, you can't magnetize air. You
can't magnetize brass.

I think you're confusing permeability with susceptibility. Even vacuum
has non-zero permeability.

I'm still considering Tom's points. What I know from decades of
experience, is if I put a brass slug into a solenoid, the inductance
goes down by a little bit. "Little" is relative to the effect of a
ferrite slug, which makes inductance go up by a lot in comparison.

The "little" is key for the PTO designs I mention, it allows rather
fine tuning with very simple mechanicals. If I think of it as shorting
turns as it moves in, that is completely out of whack in my head with
the observed changes, because shorting all the turns causes a big
change in inductance, not a small one.

Tim N3QE

Wanted, Diodes
 

On Thu, 28 Aug 2008, Tim Shoppa wrote:

I'm still considering Tom's points. What I know from decades of
experience, is if I put a brass slug into a solenoid, the inductance
goes down by a little bit. "Little" is relative to the effect of a
ferrite slug, which makes inductance go up by a lot in comparison.

Which of course is why you see iron core and ferrite slugs in high
inductance coils, but in small inductance, like you'd see at VHF,
the slugs were brass.

Or, that tuning wand with some sort of ferrite at one end and brass
at the other, so you could tell whether the tuned circuit was too high
or too low.

At that level, brass and ferrite were seen as the same thing, a means
of varying the inductance. The choice was made by how much variation
you needed, and which way, rather than what action was taking place.

Michael VE2BVW

Wanted, Diodes
 

On Aug 28, 6:25*am, Tim Shoppa wrote:
On Aug 28, 7:29*am, raypsi wrote:

On Aug 27, 3:58 pm, K7ITM wrote:
I'd bet that the shorted-turn effect is very much larger than the
permeability effect with respect to changing the inductance of the
oscillator coil.

Cheers,
Tom

I agree, except Air has no permeability, you can't magnetize air. You
can't magnetize brass.

I think you're confusing permeability with susceptibility. Even vacuum
has non-zero permeability.

I'm still considering Tom's points. What I know from decades of
experience, is if I put a brass slug into a solenoid, the inductance
goes down by a little bit. "Little" is relative to the effect of a
ferrite slug, which makes inductance go up by a lot in comparison.

The "little" is key for the PTO designs I mention, it allows rather
fine tuning with very simple mechanicals. If I think of it as shorting
turns as it moves in, that is completely out of whack in my head with
the observed changes, because shorting all the turns causes a big
change in inductance, not a small one.

Tim N3QE

Hi Tim,

OK, a 'speriment for you, and another way of looking at it that will
yield the same result:

Make two "slugs," one solid and one hollow. If it's permeability
that's doing it, the hollow one (with thin shell, of course) will have
considerably less effect. If it's the "shorted turn" effect, both
will be about the same.

Consider that there is no time-varying magnetic field inside a shell
made out of good conductor--really zero if it's a superconductor, but
dropping to practically zero after a few skin depths. So you are
removing a volume of magnetic field when you put a conducting slug in
the coil's field. With less field, there's less energy stored, which
implies lower inductance. The same thing happens when you put a coil
inside a shield-can: the inductance is reduced. A points that seems
to be not well known: the unloaded Q of a helical resonator is less
than the Q of the same coil that's not inside a shield. There are
graphs available to determine the lowering of inductance by a
cylindrical shield around a coil.

Cheers,
Tom

Wanted, Diodes
 

On Aug 28, 9:25 am, Tim Shoppa wrote:


I agree, except Air has no permeability, you can't magnetize air. You
can't magnetize brass.

I think you're confusing permeability with susceptibility. Even vacuum
has non-zero permeability.

The definition I found for:
Permeability (electromagnetism), is the degree of magnetization of a
material in response to a magnetic field

In this case 1 means no permeability.

73

n9zu

Wanted, Diodes
 

On Aug 28, 4:31 pm, K7ITM wrote:
On Aug 28, 6:25 am, Tim Shoppa wrote:



On Aug 28, 7:29 am, raypsi wrote:

On Aug 27, 3:58 pm, K7ITM wrote:
I'd bet that the shorted-turn effect is very much larger than the
permeability effect with respect to changing the inductance of the
oscillator coil.

Cheers,
Tom

I agree, except Air has no permeability, you can't magnetize air. You
can't magnetize brass.

I think you're confusing permeability with susceptibility. Even vacuum
has non-zero permeability.

I'm still considering Tom's points. What I know from decades of
experience, is if I put a brass slug into a solenoid, the inductance
goes down by a little bit. "Little" is relative to the effect of a
ferrite slug, which makes inductance go up by a lot in comparison.

The "little" is key for the PTO designs I mention, it allows rather
fine tuning with very simple mechanicals. If I think of it as shorting
turns as it moves in, that is completely out of whack in my head with
the observed changes, because shorting all the turns causes a big
change in inductance, not a small one.

Tim N3QE

Hi Tim,

OK, a 'speriment for you, and another way of looking at it that will
yield the same result:

Make two "slugs," one solid and one hollow. If it's permeability
that's doing it, the hollow one (with thin shell, of course) will have
considerably less effect. If it's the "shorted turn" effect, both
will be about the same.

Consider that there is no time-varying magnetic field inside a shell
made out of good conductor--really zero if it's a superconductor, but
dropping to practically zero after a few skin depths. So you are
removing a volume of magnetic field when you put a conducting slug in
the coil's field. With less field, there's less energy stored, which
implies lower inductance. The same thing happens when you put a coil
inside a shield-can: the inductance is reduced. A points that seems
to be not well known: the unloaded Q of a helical resonator is less
than the Q of the same coil that's not inside a shield. There are
graphs available to determine the lowering of inductance by a
cylindrical shield around a coil.

Cheers,
Tom
I agree Tom
It's not permeability that changes the inductance it's the mutual
inductance that is changing the inductance.
Any metal brought near a coil acts like another coil. If that coil is
out of phase. Then the inductance is lowered.
So with brass it's not the permeability it's the inductance of the
brass slug and the mutual inductance of the 2 coils that varies the
total inductance, of the main coil that the brass slug is in.

Towit a brass slugged adjustable coil is just a variometer.

73
n8zu

Wanted, Diodes
 

On Aug 29, 4:08*am, raypsi wrote:
On Aug 28, 4:31 pm, K7ITM wrote:

On Aug 28, 6:25 am, Tim Shoppa wrote:

On Aug 28, 7:29 am, raypsi wrote:

On Aug 27, 3:58 pm, K7ITM wrote:
I'd bet that the shorted-turn effect is very much larger than the
permeability effect with respect to changing the inductance of the
oscillator coil.

Cheers,
Tom

I agree, except Air has no permeability, you can't magnetize air. You
can't magnetize brass.

I think you're confusing permeability with susceptibility. Even vacuum
has non-zero permeability.

I'm still considering Tom's points. What I know from decades of
experience, is if I put a brass slug into a solenoid, the inductance
goes down by a little bit. "Little" is relative to the effect of a
ferrite slug, which makes inductance go up by a lot in comparison.

The "little" is key for the PTO designs I mention, it allows rather
fine tuning with very simple mechanicals. If I think of it as shorting
turns as it moves in, that is completely out of whack in my head with
the observed changes, because shorting all the turns causes a big
change in inductance, not a small one.

Tim N3QE

Hi Tim,

OK, a 'speriment for you, and another way of looking at it that will
yield the same result:

Make two "slugs," one solid and one hollow. *If it's permeability
that's doing it, the hollow one (with thin shell, of course) will have
considerably less effect. *If it's the "shorted turn" effect, both
will be about the same.

Consider that there is no time-varying magnetic field inside a shell
made out of good conductor--really zero if it's a superconductor, but
dropping to practically zero after a few skin depths. *So you are
removing a volume of magnetic field when you put a conducting slug in
the coil's field. *With less field, there's less energy stored, which
implies lower inductance. *The same thing happens when you put a coil
inside a shield-can: *the inductance is reduced. *A points that seems
to be not well known: *the unloaded Q of a helical resonator is less
than the Q of the same coil that's not inside a shield. *There are
graphs available to determine the lowering of inductance by a
cylindrical shield around a coil.

Cheers,
Tom

I agree Tom
It's not permeability that changes the inductance it's the mutual
inductance that is changing the inductance.
Any metal brought near a coil acts like another coil. If that coil is
out of phase. Then the inductance is lowered.
So with brass it's not the permeability it's the inductance of the
brass slug and the mutual inductance of the 2 coils that varies the
total inductance, of the main coil that the brass slug is in.

Towit a brass slugged adjustable coil is just a variometer.

73
n8zu

Kind of a variometer with external connections to only one of the
coils and the other one shorted out, I suppose. ;-) If you have an
actual variometer with two coils you can put in series, you can get
significantly more inductance variation than with a brass (or copper)
slug. In the case of series coils, you can both add and subtract:
you get the sum of the self-inductances of the two coils, plus OR
minus the sum of the mutual inductances. If the coils are tightly
coupled (not particularly easy to make, mechanically, for one coil
rotatable inside another...), the mutual inductances are nearly equal
to the self inductances--so for example if k=0.8 max and the coil self-
inductances are 1uH each, you can vary between 0.4uH and 3.6uH total,
a 9:1 variation. If you could manage to squeeze k(max) up to 0.9
through some heroic effort, you could go from 0.2uH to 3.8uH or 19:1
variation, enough to tune a tank over a 4:1 frequency ratio. Q isn't
very good with the coils opposing, though, since you still have the
same copper losses as when the coils are aiding.

Cheers,
Tom

Wanted, Diodes
 

raypsi wrote:
On Aug 27, 3:58 pm, K7ITM wrote:
On Aug 26, 12:05 pm, Tim Shoppa wrote:



On Aug 26, 2:26 pm, K7ITM wrote:
On Aug 26, 10:46 am, Tim Shoppa wrote:
...
The brass-screw-in-a-solenoid is something I just tried in my
reproduction of the MMR-40 and I am very impressed with its stability
and mechanical simplicity as a PTO. A similar but not identical
mechanical design is used in the WA6OTP PTO, I haven't tried it yet.
Tim.
Though not actually PTO if it's a brass screw, right?
Permeability of brass is slightly less than air, which is why the PTO
goes up in frequency as I screw the brass screw in.
It's not an iron-powder slug (which would go down in frequency as it
enters the solenoid) but it's still a PTO.
If you haven't tried them, I highly encourage you look at the PTO in
the MMR-40 and the WA6OTP PTO. Completely 100% homebrewable and I'm
very happy with the results.
Tim.
Well, I beg to differ with you about the (main) reason the frequency
changes. Consider what happens if you have two coils magnetically
coupled and you monitor the inductance of one while you apply a short
across the other one. Then consider what you'll see on the inductance
meter as you change the coupling between the measured coil and the
shorted one. The references I've been able to find so far suggest the
permeability of brass is slightly higher than that of air, but I
suppose it's a function of the composition of the brass; in any event,
I'd bet that the shorted-turn effect is very much larger than the
permeability effect with respect to changing the inductance of the
oscillator coil.

Cheers,
Tom

I agree, except Air has no permeability, you can't magnetize air. You
can't magnetize brass. What you have is a proximity detector. aka
metal detector.

73
n8zu
Brass slug acts as a shorted turn, absorbing rf and decreasing
effective inductance. You can tune a circuit with a link coupling coil
of a few turns connected to a low ohm value pot!