In case there are still any doubts about the low frequency VSWR of the 346A see below for a measurement of mine from 300kHz to 1GHz using an E5071B VNA and a 4431B-600006 Ecal module.
?
I know from experience that all of the 346A noise sources at work are very similar to this. I recall that the worst one had a VSWR of about 1.02:1 across 10MHz to about 500MHz. I don't think the VSWR was any worse than about 1.06:1 on any of them below 1MHz.
?
Below 1MHz, I think the VSWR will be flat at about 1.05:1 right down to VLF because the loss of the output attenuator will define this worst case VSWR at LF.
?
?
|
Now you have me curious; I just ran across a 346B in the lab at work this morning.? When I get back from lunch, I'll go check the date code.? ? Jim
On Fri, Oct 18, 2024 at 11:36 AM, jmr via groups.io <jmrhzu@...> wrote: It looks like my 346A can be used down to about 2MHz with good results. This may not be the case with all 346A noise sources though, especially if they are using different diodes for the newer noise sources.
?
Over the weekend, I could try and explore below 2MHz but I feel this is fairly pointless with my 346A as the ENR drops rapidly below 2MHz. However, it may be interesting to see how far down the PSA analyser can operate when I use the Noisecom noise source.
?
Both are meant to work down to 200kHz. Regardless of the result, I don't see this as a practical or reliable means to measure noise figure at such low frequencies.? I don't know if the BFR91 test amplifier can maintain a flat noise figure down below 2MHz. At some point it will start to show an increase in noise figure. I could also test a common gate JFET amplifier (with a BJT second stage) as this should hopefully show low 1/f noise and flat gain from maybe 30MHz down to very low frequencies. I just need to find it...
|
Re: An update on sponsoring the group.
Although a coworker was just telling me the other day that he knew a guy who had a border collie and several cats.? The dog would literally herd the cats!? So it is possible after all.? ? ?Jim Ford, Laguna Hills, California, USA?
On Fri, Oct 18, 2024 at 9:44 AM, Radu Bogdan Dicher <vondicher@...> wrote: Herding cats sometimes, it feels like... :) Radu.?
David -
Thanks for the update and taking on the job of herding? heading
up the group? ;-}
On 10/17/2024 7:31 PM, Dr. David
Kirkby, Kirkby Microwave Ltd via wrote:
I posted a link earlier today requesting that people that had
not sponsored the group before could consider
doing so by denoting $5. My post seems to have raised a lot of
concerns and emails, so I want to explain what happened.?
?
I know many people wanted to donate, but I don¡¯t want to
build up a big piggy bank of money to which we have no
access. If folded we would have no access to
the money. It¡¯s non-refundable. So I'd rather have enough money
to cover fees, but not an excessive amount. Hence I requested
donations were only $5, and only if you had not already donated.
?
IMHO have been very fair, and
our fees for the group have been fixed at $110/year, despite new
groups getting less facilities paying $220/year. Groups dot io
seem to be keeping the fees constant - they are not rising
inline with inflation. We are considered a legacy group.
We had got enough money to cover the fees within 20
minutes, of my post, so I disabled the sponsor
function. I have received a lot of private
emails, mentions on here, and even a complaint about the way it
was handled, so I thought I'd try to clarify why I did it the
way I did, and how? you can usefully donate to a charity if you
want to.
Firstly, the link that ended in /sponsor is created and
destroyed by automatically, depending upon whether I
enable the sponsorship feature. So I could not, ?as someone
suggested, put a custom message. Those of you who tried donating
later got a 404 error. Next time I will look into creating a
custom message, which itself has a link to the sponsor, but
warns that unless you are quick, you will likely not be able to
donate.
If anyone wanted to donate, but was unable to, then please
consider donating to one of the following charities. All want
payment in UK pounds (GBP), but PayPal, a credit or debit card
will just convert whatever you donate to your own currency.
?
If you don't want to deal in GBP, then you can send whatever
currency you want to my personal PayPal
address ( drkirkby@...),
and I will ensure it gets to the charity of your choosing.
Please do not send to my business email
address drkirkby@....
I put below in alphabetical order, a suggested list of UK
charities. I know some people like donating to small charities.
The third in the list is 100% voluntary, with zero employees.
The fourth in the list is very small.? The other charities are
better known, and bigger.
?
1) Cat¡¯s Protection League
?
2) Dog's Trust
?
3) German Shepherd Dog Rescue (100%
voluntary, zero employees).
(Declared conflict of interest, I own a German Shepherd)
?
4) Girlguiding (A small charity, but it
does have paid employees)
This helps? young girls develop new skills and build
self-confidence.
?
5) Open University
This provides education, including degrees. The courses are
very high quality, but funding is tight.
?
A lot of material is made freely available too.
(Declared conflict of interest, I'm currently doing a BSc
(honors) degree in mathematics at the Open University)
?
6) Royal Society for the Prevention of Cruelty to
Animals (RSPCA)
?
?
?
|
This is a pretty silly argument to make.? As Roy says, many chemicals are hygroscopic including zinc chloride.? They absorb water readily through water vapor in the air.? And that is how zinc chloride can become acidic.??
?
I'm sure it is a mistake we've all made before - using flux on electronics.? But there are so many readily available fluxes for different applications, I'm not sure why you'd make an argument for using it now.
|
It looks like my 346A can be used down to about 2MHz with good results. This may not be the case with all 346A noise sources though, especially if they are using different diodes for the newer noise sources.
?
Over the weekend, I could try and explore below 2MHz but I feel this is fairly pointless with my 346A as the ENR drops rapidly below 2MHz. However, it may be interesting to see how far down the PSA analyser can operate when I use the Noisecom noise source.
?
Both are meant to work down to 200kHz. Regardless of the result, I don't see this as a practical or reliable means to measure noise figure at such low frequencies.? I don't know if the BFR91 test amplifier can maintain a flat noise figure down below 2MHz. At some point it will start to show an increase in noise figure. I could also test a common gate JFET amplifier (with a BJT second stage) as this should hopefully show low 1/f noise and flat gain from maybe 30MHz down to very low frequencies. I just need to find it...
|
I dug out my precision analyser preamp (homebrew) and used this instead of using the internal preamp in the PSA analyser. My preamp has ultra low VSWR and a 2.8dB noise figure across a few MHz up to about 1GHz. The combination of the low VSWR and lower noise figure should minimise the measurement uncertainty when using the 346A noise source. See below for a fresh measurement of the BFR91 amplifier using my preamp inline with the PSA analyser.
?
?
?
This has no averaging but you can see how much cleaner the traces are when using my external preamp. I also measured the amplifier on a 2 port VNA after an Ecal calibration at -25dBm source power.
?
?
You can see that the gain is very flat at 12.5dB across 300kHz to over 50MHz. This agrees with the gain measurement using the 346A noise source and the PSA analyser.
?
My external preamp was designed to have very low VSWR from 1MHz to 500MHz and a sub 3dB noise figure. It also has very flat gain across this range although this is less important.
?
?
You can see the input VSWR of my precision preamp is ultra low across 1MHz to 500MHz.??
?
?
?
This plot shows how flat the gain of the external precision preamp is. It was designed to act as a precision wideband amplifier to use for instrumentation and you can see there is no passband ripple and the VSWR is impressively low. The noise figure is a flat 2.8dB from a few MHz to well over 500MHz. The noise figure creeps up slightly down at 1MHz, but only by a small amount.?
?
It really helps to minimise measurement uncertainty when doing noise figure measurements with the 346A and PSA analyser.
?
Despite all this, I can't guarantee how accurate the subsequent noise figure results are below 10MHz for the BFR93 test amplifier, but if I assume the gain and noise figure is flat with frequency down to 2MHz, then it looks like I can assume high confidence in the results I've achieved. I've taken reasonable steps to minimise measurement uncertainty.
?
It would be interesting to see how others would approach this task and what results they achieved. Because the noise performance of the 346A isn't specified below 10MHz then it may be the case that there could be differences (between various 346A devices) in how flat the noise output is below 10MHz. I've got access to about eight 346A noise sources at work (but sadly no 346B) so I could maybe ask to borrow them and test them one by one? Some already have a fairly low ENR at 10MHz of only 5.0dB. I've been using them at work for about 20 years and I think they are are all 2004 (44) date code devices.
?
My 346A here at home has a 1993 date code.
?
?
?
?
?
?
?
?
?
|
Something over 65 years ago I helped? install an RCA UHF transmitter.? RCA furnished a liquid flux, I think they called Kempane or something like that.? It came in a bottle with a brush and was used for soft soldering flanges on large copper transmission lines with a torch.? It worked very well.? In years since I wished I had some for soft-soldering waveguide flanges.? Is there a present day generic equivalent?
?
Bruce, KG6OJI
|
No, but I knew some engineers from that area, and often went to the Cincinnati Hamfest since I lived in Middletown.
I often had them hanging around my tables, discussing the stations where they worked. One was an engeer for the eductaional stations in Kenty when I first knew him. I moslly dealt n used test equip,ent, and some broardcast equipment. The only thing let from that era is a Scully 280 record amplifier..??
I worked in stations in Alaka, and Florida
Michael, Your name sounds vaguely familiar to me. Have you ever worked for KET or KEWS or other facility here in Kentucky?
|
yes, Thank you , note
the correction I was moving the 25% vinegar jug this morning...
it was on my mind.
¸é±ð²Ô¨¦±ð
On 10/18/24 10:10 AM, Dave Daniel via
groups.io wrote:
toggle quoted message
Show quoted text
The acid in lemon juice is citric acid. Vinegar contains acetic
acid.
DaveD
KC0WJN
Thanks
for all the fish.
==============================
All spelling mistakes are the responsibilty of
the reader (Rick Renz, STK, ca. 1994)
==============================
On Oct 18, 2024, at 12:38, ¸é±ð²Ô¨¦±ð via
groups.io <k6fsb.1@...> wrote:
?
IIRC lemon
juice is mild acetic acid
¸é±ð²Ô¨¦±ð
On 10/18/24 6:26 AM, Jim Ford
via groups.io wrote:
Thanks, Chuck.? I've forgotten much of my chemistry since
I switched majors from biochemistry to EE about 40 years
ago.? IIRC, fluxes come in several classes, R for pure
rosin - not activated, RMA for rosin mildly activated - a
small amount of acid added, and RA for rosin activated - a
relatively large amount of acid added.? Then there's the
"acid" flux - no rosin at all, and as people have said,
suitable for plumbing and not for electronics.? I had
heard years ago that Hughes Aircraft (since split into
Raytheon where I work and Boeing) was using lemon juice
instead of rosin flux, but I haven't tried that.? ? ? ?
Jim
On Fri, Oct 18, 2024 at 5:40 AM, Chuck Harris
Ok, let's talk about
this.
It is true that the OP didn't mention whether he was
using
a paste, or a liquid... just that what he was using
had 27%
ZnCl.? If the other 73% is water, that would cause
problems
all of its own... If it is 73% something else, perhaps
not.
The pubchem listing you brought into this conversation
must
be for an aqueous solution of ZnCl and water, or pH
would
be undefined.
[pH == -log10(H+), or 14 - log10(OH-)]
It should be obvious that ZnCl has no water, just as
the
NaCl in the shaker in your kitchen has no water.
A liquid solution of ZnCl in water would be very
difficult
to handle in an electronic application. it would run
everywhere leading to the anecdotes that sprung up
like
mushrooms on the mention of ZnCl as a flux...
About the only way liquid ZnCl flux could be used in
electronics work is dipping a lead in it before
soldering.
Liquid ZnCl flux is mostly water and HCl, so it is bad
to even have around electronics equipment.
I inferred by the OP's use case, that he was talking
about the old fashioned ZnCl solder paste concoction
that has been used for decades in the assembly of
point-to-point soldered electronic equipment.
At this point in the conversation only he knows which
of
us made the correct guess.
ZnCl is a compound that is neither an acid, nor a
base.
It is neutral.? ZnCl in water is far more interesting.
It is also neither an acid, nor a base.? It is an
ionic
solution of Zn+, Cl-, H+ and OH- ions all in a perfect
balance.
That said, it is impossible to say which +ions of the
ionic solution are "coupled" with which -ions, so a
ZnCl
solution is at the same time comprised of:
H+ Cl-, Zn+ OH-, and H+ OH-
It looks as much like hydrochloric acid (a strong
acid),
as it does like ZnCl (a neutral salt), as it does like
zinc hydroxide (a strong base).
The typical liquid ZnCl flux is not "killed".? It is
left
a little spicy by not completely neutralizing the HCl
with
ZnOH.
It is a ZnCl/HCl solution.
Rosin flux:
Rosin flux that is not activated, will do nothing to
help
in soldering a joint made up of slightly oxidized
copper
pieces.? The solder will ball up, never wetting the
copper.
It may help in soldering a joint with clean metals, as
it
will keep the oxygen in the air from reacting with the
hot copper.
To make such a joint, you would have to either freshly
sand the oxide off of the copper, or apply a scrubbing
action (to break up the oxides) with your soldering
iron
tip.
To make soldering a little easier, manufacturers
"activate"
the rosin to various degrees.? Activation is another
word
for adding acid.? The acid combines with the oxide,
puts
it into solution, where it floats to the surface of
the
joint and sits relatively harmlessly until moisture
from
the air gets involved.? Just as the ZnCl in solder
paste
does.
-Chuck Harris
On Thu, 17 Oct 2024 13:40:47 -0700 "Robert G8RPI via
groups.io"
<robert8rpi@...>
wrote:
> Chuck said:
> "Come on guys, it really isn't that bad. ?The
stuff he
> is talking about is a petroleum jelly based zinc
chloride
> compound. ?Zinc Chloride is a killed acid. ?That
means that
> they dissolve enough zinc into HCL that it can
take no more,
> and is neutral pH.
> It is non-corrosive, and says so in bold red
letters right
> on the can."
>
> Not according to
>
who say "It
> is corrosive to metals" The key is in the
"chloride". I don't know
> how you determined the OP had a jelly based flux
as he didn't say.
> Not all flux is corrosive. Rosin flux is not. It
does not have to be
> it works by excluding air (oxygen) from the hot
joint. A solution fod
> zinc hloride is acidic with a PH of about 4. It
is not suitable for
> electrical applications.
>
> Robert.
>
>
>
>
>
|
Michael, Your name sounds vaguely familiar to me. Have you ever worked for KET or KEWS or other facility here in Kentucky?
|
The acid in lemon juice is citric acid. Vinegar contains acetic acid. DaveD KC0WJN
Thanks for all the fish.
============================== All spelling mistakes are the responsibilty of the reader (Rick Renz, STK, ca. 1994) ==============================
toggle quoted message
Show quoted text
On Oct 18, 2024, at 12:38, ¸é±ð²Ô¨¦±ð via groups.io <k6fsb.1@...> wrote:
?
IIRC lemon juice is
mild acetic acid
¸é±ð²Ô¨¦±ð
On 10/18/24 6:26 AM, Jim Ford via
groups.io wrote:
Thanks, Chuck.? I've forgotten much of my chemistry since I
switched majors from biochemistry to EE about 40 years ago.? IIRC,
fluxes come in several classes, R for pure rosin - not activated,
RMA for rosin mildly activated - a small amount of acid added, and
RA for rosin activated - a relatively large amount of acid added.?
Then there's the "acid" flux - no rosin at all, and as people have
said, suitable for plumbing and not for electronics.? I had heard
years ago that Hughes Aircraft (since split into Raytheon where I
work and Boeing) was using lemon juice instead of rosin flux, but
I haven't tried that.? ? ? ? Jim
On Fri, Oct 18, 2024 at 5:40 AM, Chuck Harris
Ok, let's talk about this.
It is true that the OP didn't mention whether he was using
a paste, or a liquid... just that what he was using had 27%
ZnCl.? If the other 73% is water, that would cause problems
all of its own... If it is 73% something else, perhaps not.
The pubchem listing you brought into this conversation must
be for an aqueous solution of ZnCl and water, or pH would
be undefined.
[pH == -log10(H+), or 14 - log10(OH-)]
It should be obvious that ZnCl has no water, just as the
NaCl in the shaker in your kitchen has no water.
A liquid solution of ZnCl in water would be very difficult
to handle in an electronic application. it would run
everywhere leading to the anecdotes that sprung up like
mushrooms on the mention of ZnCl as a flux...
About the only way liquid ZnCl flux could be used in
electronics work is dipping a lead in it before soldering.
Liquid ZnCl flux is mostly water and HCl, so it is bad
to even have around electronics equipment.
I inferred by the OP's use case, that he was talking
about the old fashioned ZnCl solder paste concoction
that has been used for decades in the assembly of
point-to-point soldered electronic equipment.
At this point in the conversation only he knows which of
us made the correct guess.
ZnCl is a compound that is neither an acid, nor a base.
It is neutral.? ZnCl in water is far more interesting.
It is also neither an acid, nor a base.? It is an ionic
solution of Zn+, Cl-, H+ and OH- ions all in a perfect
balance.
That said, it is impossible to say which +ions of the
ionic solution are "coupled" with which -ions, so a ZnCl
solution is at the same time comprised of:
H+ Cl-, Zn+ OH-, and H+ OH-
It looks as much like hydrochloric acid (a strong acid),
as it does like ZnCl (a neutral salt), as it does like
zinc hydroxide (a strong base).
The typical liquid ZnCl flux is not "killed".? It is left
a little spicy by not completely neutralizing the HCl with
ZnOH.
It is a ZnCl/HCl solution.
Rosin flux:
Rosin flux that is not activated, will do nothing to help
in soldering a joint made up of slightly oxidized copper
pieces.? The solder will ball up, never wetting the copper.
It may help in soldering a joint with clean metals, as it
will keep the oxygen in the air from reacting with the
hot copper.
To make such a joint, you would have to either freshly
sand the oxide off of the copper, or apply a scrubbing
action (to break up the oxides) with your soldering iron
tip.
To make soldering a little easier, manufacturers "activate"
the rosin to various degrees.? Activation is another word
for adding acid.? The acid combines with the oxide, puts
it into solution, where it floats to the surface of the
joint and sits relatively harmlessly until moisture from
the air gets involved.? Just as the ZnCl in solder paste
does.
-Chuck Harris
On Thu, 17 Oct 2024 13:40:47 -0700 "Robert G8RPI via
groups.io"
<robert8rpi@...> wrote:
> Chuck said:
> "Come on guys, it really isn't that bad. ?The stuff he
> is talking about is a petroleum jelly based zinc chloride
> compound. ?Zinc Chloride is a killed acid. ?That means
that
> they dissolve enough zinc into HCL that it can take no
more,
> and is neutral pH.
> It is non-corrosive, and says so in bold red letters
right
> on the can."
>
> Not according to
>
who say "It
> is corrosive to metals" The key is in the "chloride". I
don't know
> how you determined the OP had a jelly based flux as he
didn't say.
> Not all flux is corrosive. Rosin flux is not. It does not
have to be
> it works by excluding air (oxygen) from the hot joint. A
solution fod
> zinc hloride is acidic with a PH of about 4. It is not
suitable for
> electrical applications.
>
> Robert.
>
>
>
>
>
|
Re: An update on sponsoring the group.
Herding cats sometimes, it feels like... :) Radu.?
David -
Thanks for the update and taking on the job of herding? heading
up the group? ;-}
On 10/17/2024 7:31 PM, Dr. David
Kirkby, Kirkby Microwave Ltd via wrote:
I posted a link earlier today requesting that people that had
not sponsored the group before could consider
doing so by denoting $5. My post seems to have raised a lot of
concerns and emails, so I want to explain what happened.?
?
I know many people wanted to donate, but I don¡¯t want to
build up a big piggy bank of money to which we have no
access. If folded we would have no access to
the money. It¡¯s non-refundable. So I'd rather have enough money
to cover fees, but not an excessive amount. Hence I requested
donations were only $5, and only if you had not already donated.
?
IMHO have been very fair, and
our fees for the group have been fixed at $110/year, despite new
groups getting less facilities paying $220/year. Groups dot io
seem to be keeping the fees constant - they are not rising
inline with inflation. We are considered a legacy group.
We had got enough money to cover the fees within 20
minutes, of my post, so I disabled the sponsor
function. I have received a lot of private
emails, mentions on here, and even a complaint about the way it
was handled, so I thought I'd try to clarify why I did it the
way I did, and how? you can usefully donate to a charity if you
want to.
Firstly, the link that ended in /sponsor is created and
destroyed by automatically, depending upon whether I
enable the sponsorship feature. So I could not, ?as someone
suggested, put a custom message. Those of you who tried donating
later got a 404 error. Next time I will look into creating a
custom message, which itself has a link to the sponsor, but
warns that unless you are quick, you will likely not be able to
donate.
If anyone wanted to donate, but was unable to, then please
consider donating to one of the following charities. All want
payment in UK pounds (GBP), but PayPal, a credit or debit card
will just convert whatever you donate to your own currency.
?
If you don't want to deal in GBP, then you can send whatever
currency you want to my personal PayPal
address ( drkirkby@...),
and I will ensure it gets to the charity of your choosing.
Please do not send to my business email
address drkirkby@....
I put below in alphabetical order, a suggested list of UK
charities. I know some people like donating to small charities.
The third in the list is 100% voluntary, with zero employees.
The fourth in the list is very small.? The other charities are
better known, and bigger.
?
1) Cat¡¯s Protection League
?
2) Dog's Trust
?
3) German Shepherd Dog Rescue (100%
voluntary, zero employees).
(Declared conflict of interest, I own a German Shepherd)
?
4) Girlguiding (A small charity, but it
does have paid employees)
This helps? young girls develop new skills and build
self-confidence.
?
5) Open University
This provides education, including degrees. The courses are
very high quality, but funding is tight.
?
A lot of material is made freely available too.
(Declared conflict of interest, I'm currently doing a BSc
(honors) degree in mathematics at the Open University)
?
6) Royal Society for the Prevention of Cruelty to
Animals (RSPCA)
?
?
?
|
IIRC lemon juice is
mild acetic acid
¸é±ð²Ô¨¦±ð
On 10/18/24 6:26 AM, Jim Ford via
groups.io wrote:
toggle quoted message
Show quoted text
Thanks, Chuck.? I've forgotten much of my chemistry since I
switched majors from biochemistry to EE about 40 years ago.? IIRC,
fluxes come in several classes, R for pure rosin - not activated,
RMA for rosin mildly activated - a small amount of acid added, and
RA for rosin activated - a relatively large amount of acid added.?
Then there's the "acid" flux - no rosin at all, and as people have
said, suitable for plumbing and not for electronics.? I had heard
years ago that Hughes Aircraft (since split into Raytheon where I
work and Boeing) was using lemon juice instead of rosin flux, but
I haven't tried that.? ? ? ? Jim
On Fri, Oct 18, 2024 at 5:40 AM, Chuck Harris
Ok, let's talk about this.
It is true that the OP didn't mention whether he was using
a paste, or a liquid... just that what he was using had 27%
ZnCl.? If the other 73% is water, that would cause problems
all of its own... If it is 73% something else, perhaps not.
The pubchem listing you brought into this conversation must
be for an aqueous solution of ZnCl and water, or pH would
be undefined.
[pH == -log10(H+), or 14 - log10(OH-)]
It should be obvious that ZnCl has no water, just as the
NaCl in the shaker in your kitchen has no water.
A liquid solution of ZnCl in water would be very difficult
to handle in an electronic application. it would run
everywhere leading to the anecdotes that sprung up like
mushrooms on the mention of ZnCl as a flux...
About the only way liquid ZnCl flux could be used in
electronics work is dipping a lead in it before soldering.
Liquid ZnCl flux is mostly water and HCl, so it is bad
to even have around electronics equipment.
I inferred by the OP's use case, that he was talking
about the old fashioned ZnCl solder paste concoction
that has been used for decades in the assembly of
point-to-point soldered electronic equipment.
At this point in the conversation only he knows which of
us made the correct guess.
ZnCl is a compound that is neither an acid, nor a base.
It is neutral.? ZnCl in water is far more interesting.
It is also neither an acid, nor a base.? It is an ionic
solution of Zn+, Cl-, H+ and OH- ions all in a perfect
balance.
That said, it is impossible to say which +ions of the
ionic solution are "coupled" with which -ions, so a ZnCl
solution is at the same time comprised of:
H+ Cl-, Zn+ OH-, and H+ OH-
It looks as much like hydrochloric acid (a strong acid),
as it does like ZnCl (a neutral salt), as it does like
zinc hydroxide (a strong base).
The typical liquid ZnCl flux is not "killed".? It is left
a little spicy by not completely neutralizing the HCl with
ZnOH.
It is a ZnCl/HCl solution.
Rosin flux:
Rosin flux that is not activated, will do nothing to help
in soldering a joint made up of slightly oxidized copper
pieces.? The solder will ball up, never wetting the copper.
It may help in soldering a joint with clean metals, as it
will keep the oxygen in the air from reacting with the
hot copper.
To make such a joint, you would have to either freshly
sand the oxide off of the copper, or apply a scrubbing
action (to break up the oxides) with your soldering iron
tip.
To make soldering a little easier, manufacturers "activate"
the rosin to various degrees.? Activation is another word
for adding acid.? The acid combines with the oxide, puts
it into solution, where it floats to the surface of the
joint and sits relatively harmlessly until moisture from
the air gets involved.? Just as the ZnCl in solder paste
does.
-Chuck Harris
On Thu, 17 Oct 2024 13:40:47 -0700 "Robert G8RPI via
groups.io"
<robert8rpi@...> wrote:
> Chuck said:
> "Come on guys, it really isn't that bad. ?The stuff he
> is talking about is a petroleum jelly based zinc chloride
> compound. ?Zinc Chloride is a killed acid. ?That means
that
> they dissolve enough zinc into HCL that it can take no
more,
> and is neutral pH.
> It is non-corrosive, and says so in bold red letters
right
> on the can."
>
> Not according to
>
who say "It
> is corrosive to metals" The key is in the "chloride". I
don't know
> how you determined the OP had a jelly based flux as he
didn't say.
> Not all flux is corrosive. Rosin flux is not. It does not
have to be
> it works by excluding air (oxygen) from the hot joint. A
solution fod
> zinc hloride is acidic with a PH of about 4. It is not
suitable for
> electrical applications.
>
> Robert.
>
>
>
>
>
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Re: An update on sponsoring the group.
David -
Thanks for the update and taking on the job of herding? heading
up the group? ;-}
On 10/17/2024 7:31 PM, Dr. David
Kirkby, Kirkby Microwave Ltd via groups.io wrote:
toggle quoted message
Show quoted text
I posted a link earlier today requesting that people that had
not sponsored the group before could consider
doing so by denoting $5. My post seems to have raised a lot of
concerns and emails, so I want to explain what happened.?
?
I know many people wanted to donate, but I don¡¯t want to
build up a big piggy bank of money to which we have no
access. If group.io folded we would have no access to
the money. It¡¯s non-refundable. So I'd rather have enough money
to cover fees, but not an excessive amount. Hence I requested
donations were only $5, and only if you had not already donated.
?
IMHO groups.io have been very fair, and
our fees for the group have been fixed at $110/year, despite new
groups getting less facilities paying $220/year. Groups dot io
seem to be keeping the fees constant - they are not rising
inline with inflation. We are considered a legacy group.
We had got enough money to cover the fees within 20
minutes, of my post, so I disabled the sponsor
function. I have received a lot of private
emails, mentions on here, and even a complaint about the way it
was handled, so I thought I'd try to clarify why I did it the
way I did, and how? you can usefully donate to a charity if you
want to.
Firstly, the link that ended in /sponsor is created and
destroyed by groups.io automatically, depending upon whether I
enable the sponsorship feature. So I could not, ?as someone
suggested, put a custom message. Those of you who tried donating
later got a 404 error. Next time I will look into creating a
custom message, which itself has a link to the sponsor, but
warns that unless you are quick, you will likely not be able to
donate.
If anyone wanted to donate, but was unable to, then please
consider donating to one of the following charities. All want
payment in UK pounds (GBP), but PayPal, a credit or debit card
will just convert whatever you donate to your own currency.
?
If you don't want to deal in GBP, then you can send whatever
currency you want to my personal PayPal
address ( drkirkby@...),
and I will ensure it gets to the charity of your choosing.
Please do not send to my business email
address drkirkby@....
I put below in alphabetical order, a suggested list of UK
charities. I know some people like donating to small charities.
The third in the list is 100% voluntary, with zero employees.
The fourth in the list is very small.? The other charities are
better known, and bigger.
?
1) Cat¡¯s Protection League
?
2) Dog's Trust
?
3) German Shepherd Dog Rescue (100%
voluntary, zero employees).
(Declared conflict of interest, I own a German Shepherd)
?
4) Girlguiding (A small charity, but it
does have paid employees)
This helps? young girls develop new skills and build
self-confidence.
?
5) Open University
This provides education, including degrees. The courses are
very high quality, but funding is tight.
?
A lot of material is made freely available too.
(Declared conflict of interest, I'm currently doing a BSc
(honors) degree in mathematics at the Open University)
?
6) Royal Society for the Prevention of Cruelty to
Animals (RSPCA)
?
?
?
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No. I've only wrked on Comark, Gates and RCA TV transmitters, butt I received the salvage of a 5KW Channel 8 NTSC tranmitter from Vietnam, after it was shot up by the enemy, and the engineers were killed I had a similar transmitter at Ft Greely. but it didn't have the two amplifer cabinets. That Aural fiinal would have been great for a Two Meter repeater! The RCA used water cooled power tetrodes that were designed for just the TTU-265 series of UHF ransmitters.?
RCA was safety conscious, and there were many interlock switches in that transmitter. Gates and Comark had them as well, but the RCA was seven, four foot square custom aluminum cabinets and those switches could be knocked out of alignment, causing intermittent shutdowns. TIt was one of the first 'High Power UHF transmitters in the US. Ours was licensed for 1.3 MW EIRP, The Comark was 5 MW EIRP, but thee gates were low power.80 + 500Watts each. The FCC license was interesting. It stated 500 Watts, oer as deemed necessary, and the expiration date was, Until no longer needed. Ft Greely also had a Cates BC250 AM transmitter with a similar license. I was the only engineer on that base, and the stations were cra when I arrived BTW, have you ever seen a broadcast station using a center tapped dipole, instead of a tower? It was the only one I ever saw! I think it was onn 980 KHz, but I left there over 50 years ago.
On Thu, Oct 17, 2024 at 06:55 PM, Michael A. Terrell wrote:
I moved and rebuilt a 1952 RCA TV transmitter, a couple decades ago.
Michael... did you ever have to work on a Pye TVT UHF transmitter?? I'm sure they were a bit easier across the pond in the UK, but over here, they were not only their usual deadly, with non-interlocked 35KV places accessible with the removal of only a few screws, but to work on the steam condensers or anything else in the cooling circuit for the klystrons, one had to source metric copper pipe hardware.? Surely a walk in the park in it's motherland, but not so much here in the states.
I took great pleasure in ventilating parts of that transmitter with a .357 magnum revolver when we decommissioned that one.
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On Thu, Oct 17, 2024 at 06:55 PM, Michael A. Terrell wrote:
I moved and rebuilt a 1952 RCA TV transmitter, a couple decades ago.
Michael... did you ever have to work on a Pye TVT UHF transmitter?? I'm sure they were a bit easier across the pond in the UK, but over here, they were not only their usual deadly, with non-interlocked 35KV places accessible with the removal of only a few screws, but to work on the steam condensers or anything else in the cooling circuit for the klystrons, one had to source metric copper pipe hardware.? Surely a walk in the park in it's motherland, but not so much here in the states.
I took great pleasure in ventilating parts of that transmitter with a .357 magnum revolver when we decommissioned that one.
|
Re: Anyone got documents for these instruments?
Hello David,
?
I have just uploaded the files which I mentioned as possibly of use, some into new directories. There are a couple which I wouldn't know what appropriate directory they would fall into (I know the instruments themselves) so I uploaded them into the head directory as you suggested to sort out later.
?
I hope these are of use to some here.
?
Again my kind regards and have a good weekend!
?
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On Fri, Oct 18, 2024 at 06:26 AM, Jim Ford wrote:
R for pure rosin - not activated
AFAIK... rosin for flux... like that from Slash Pine tapping (in the U.S.) contains about 50% abietic acid.
That's a weak organic acid.
At room temperature... it's a solid pale yellow compound, that has that pine smell.
?
You can take 'pure' rosin and dissolve it in alcohol... to make a rosin flux... of various viscosity.
It does 'help' remove oxidation from copper.
You can see that if you 'pool' some on... and then put the tip of the iron in. (The copper will become brighter.)
?
IMO... I don't think anyone really knows what a flux 'activator' is. (Soldering is a lot easier to 'do' than to 'understand')
But here's a list.? (some are used in 'hard' soldering)
Acidic Activators
Common Activators for Rosin Flux
Zinc Chloride (ZnCl?) ? ??
Hydrochloric Acid (HCl)
Ammonium Chloride (NH?Cl)
Sodium Chloride (NaCl)
Potassium Chloride (KCl)
Organic Acids
Tartaric Acid ? ? ?
Glycolic Acid
Sodium Bicarbonate (NaHCO?)
Boric Acid (H?BO?)
Basic? Activators? ?
Amines
Ethanolamine
Diethanolamine
Triethanolamine
?
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On Fri, Oct 18, 2024 at 05:40 AM, Chuck Harris wrote:
ZnCl in water is far more interesting.
It is also neither an acid, nor a base. It is an ionic
solution of Zn+, Cl-, H+ and OH- ions all in a perfect
balance.
I was following the thread...AFAIK...
Zinc chloride is an odorless white powder.
It is extremely soluble in water
It also readily absorbs atmospheric moisture... to crystallize and clump... so, we used to keep it in a desiccator.
It can also absorb enough water to form a liquid.
Zinc chloride also dissolves in ?ethanol, acetone, and glycerol.
?
The damp crystals, or liquefied crystals, are/is very corrosive, having a pH of approximately 1 to 4, so acidic.
A water solution of zinc chloride is also acidic... the acidity depending on the concentration.
It does not form a very acidic solution with ethanol, acetone, or glycerol.
?
Zinc chloride is a Lewis acid.
In a water solution, the Zn ions undergo hydrolysis... that produces hydrogen ions... and that's responsible for the acidity.
?
The zinc chloride in a carbon zinc battery... part of the electrolyte paste... it is not very acidic
When the battery leaks and the zinc chloride absorbs moisture... then your favorite Lewis acid does it's thing.
?
If you have zinc chloride crystals... or powder... on or around, steel, iron, or copper... corrosion will eventually happen.
?
After using a flux, having zinc chloride, you might see traces of white powder.
If it's zinc chloride then washing with water can dissolve it.
Some zinc chloride may remain... because the 'flux' sometimes possesses 'gooey' stuff ... and often that 'gooey' stuff doesn't like to wash away with water.
?
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ChatGPT said:
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Thanks, Chuck.? I've forgotten much of my chemistry since I switched majors from biochemistry to EE about 40 years ago.? IIRC, fluxes come in several classes, R for pure rosin - not activated, RMA for rosin mildly activated - a small amount of acid added, and RA for rosin activated - a relatively large amount of acid added.? Then there's the "acid" flux - no rosin at all, and as people have said, suitable for plumbing and not for electronics.? I had heard years ago that Hughes Aircraft (since split into Raytheon where I work and Boeing) was using lemon juice instead of rosin flux, but I haven't tried that.? ? ? ? Jim
On Fri, Oct 18, 2024 at 5:40 AM, Chuck Harris <cfharris@...> wrote: Ok, let's talk about this.
It is true that the OP didn't mention whether he was using
a paste, or a liquid... just that what he was using had 27%
ZnCl.? If the other 73% is water, that would cause problems
all of its own... If it is 73% something else, perhaps not.
The pubchem listing you brought into this conversation must
be for an aqueous solution of ZnCl and water, or pH would
be undefined.
[pH == -log10(H+), or 14 - log10(OH-)]
It should be obvious that ZnCl has no water, just as the
NaCl in the shaker in your kitchen has no water.
A liquid solution of ZnCl in water would be very difficult
to handle in an electronic application. it would run
everywhere leading to the anecdotes that sprung up like
mushrooms on the mention of ZnCl as a flux...
About the only way liquid ZnCl flux could be used in
electronics work is dipping a lead in it before soldering.
Liquid ZnCl flux is mostly water and HCl, so it is bad
to even have around electronics equipment.
I inferred by the OP's use case, that he was talking
about the old fashioned ZnCl solder paste concoction
that has been used for decades in the assembly of
point-to-point soldered electronic equipment.
At this point in the conversation only he knows which of
us made the correct guess.
ZnCl is a compound that is neither an acid, nor a base.
It is neutral.? ZnCl in water is far more interesting.
It is also neither an acid, nor a base.? It is an ionic
solution of Zn+, Cl-, H+ and OH- ions all in a perfect
balance.
That said, it is impossible to say which +ions of the
ionic solution are "coupled" with which -ions, so a ZnCl
solution is at the same time comprised of:
H+ Cl-, Zn+ OH-, and H+ OH-
It looks as much like hydrochloric acid (a strong acid),
as it does like ZnCl (a neutral salt), as it does like
zinc hydroxide (a strong base).
The typical liquid ZnCl flux is not "killed".? It is left
a little spicy by not completely neutralizing the HCl with
ZnOH.
It is a ZnCl/HCl solution.
Rosin flux:
Rosin flux that is not activated, will do nothing to help
in soldering a joint made up of slightly oxidized copper
pieces.? The solder will ball up, never wetting the copper.
It may help in soldering a joint with clean metals, as it
will keep the oxygen in the air from reacting with the
hot copper.
To make such a joint, you would have to either freshly
sand the oxide off of the copper, or apply a scrubbing
action (to break up the oxides) with your soldering iron
tip.
To make soldering a little easier, manufacturers "activate"
the rosin to various degrees.? Activation is another word
for adding acid.? The acid combines with the oxide, puts
it into solution, where it floats to the surface of the
joint and sits relatively harmlessly until moisture from
the air gets involved.? Just as the ZnCl in solder paste
does.
-Chuck Harris
On Thu, 17 Oct 2024 13:40:47 -0700 "Robert G8RPI via groups.io"
<robert8rpi@...> wrote:
> Chuck said:
> "Come on guys, it really isn't that bad. ?The stuff he
> is talking about is a petroleum jelly based zinc chloride
> compound. ?Zinc Chloride is a killed acid. ?That means that
> they dissolve enough zinc into HCL that it can take no more,
> and is neutral pH.
> It is non-corrosive, and says so in bold red letters right
> on the can."
>
> Not according to
> who say "It
> is corrosive to metals" The key is in the "chloride". I don't know
> how you determined the OP had a jelly based flux as he didn't say.
> Not all flux is corrosive. Rosin flux is not. It does not have to be
> it works by excluding air (oxygen) from the hot joint. A solution fod
> zinc hloride is acidic with a PH of about 4. It is not suitable for
> electrical applications.
>
> Robert.
>
>
>
>
>
|
Frank Mashockie
ebrucehunter
Michael A. Terrell
Trevor Gale