Re: Measuring Resonant Frequency of Traps
This little noise generator would work fine: ??
On Thu, Dec 19, 2019 at 4:26 PM sigcom1 < sigcom@...> wrote: I second what Dale says, however (since measuring traps is the subject),? a simple noise generator along with a receiver can be employed to measure traps.? Example:???>.
73.......Steve Smith WB6TNL
? ? ? ? ? ? ? ? "Snort Rosin"
?On Thu, Dec 19, 2019 at 02:07 PM, Dale Hardin wrote:
Don't forget the "noise bridge".? Here is a simple one that can be built out of junk parts:
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Re: Measuring Resonant Frequency of Traps
I second what Dale says, however (since measuring traps is the subject),? a simple noise generator along with a receiver can be employed to measure traps.? Example:???>.
73.......Steve Smith WB6TNL
? ? ? ? ? ? ? ? "Snort Rosin"
?On Thu, Dec 19, 2019 at 02:07 PM, Dale Hardin wrote:
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Don't forget the "noise bridge".? Here is a simple one that can be built out of junk parts:
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Re: Varactor Diode C Measurement
Chuck,
On page 16 of? ?
there's an equation for the capacitance of a reverse biased diode
? Cj =? ?A/2 * ((2*q*e/(V0-V))*(Nd*Na/(Nd+Na)))**(1/2)
From that, it appears that the junction capacitance is inversely proportional
to the sqrt of the voltage applied (voltage measured relative to V0)
Which to my eye, agrees with those curves.
If you happen to be exceptionally curious, the derivation is in the pages prior.
And if you're lucky, he defines some of the variables and constants in lecture 26.?
Extra credit:?
So, as the voltage across the diode decreases, the change in capacitance due to some delta-V (voltage noise) increases.
But since we are using a resistive divider to create the voltage across the diode,
any noise in the power supply voltage is reduced proportional to that resistive divider.
Which one wins?
Jerry
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On Thu, Dec 19, 2019 at 12:12 PM, Chuck Carpenter wrote:
Jerry, the shape of the curve in fig 3 is typical of?junctions of non?"purpose built" diodes. (like that term).
I've attached a set of curves from K7QO.? The curve at the bottom is a power diode.? Note that there is not much change from about 5 V so higher voltages don't help much.
--
Chuck, W5USJ (ex K2OFN)
Point, Rains Co, TX? EM22cv
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Re: Measuring Resonant Frequency of Traps
Don't forget the "noise bridge".? Here is a simple one that can be built out of junk parts:
It is a very useful and cheaply built antenna testing tool.? Dale KS4NS
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Re: Varactor Diode C Measurement
Gary,? What was the specified part?
--
Chuck, W5USJ (ex K2OFN)
Point, Rains Co, TX? EM22cv
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Re: Varactor Diode C Measurement
Jerry, the shape of the curve in fig 3 is typical of?junctions of non?"purpose built" diodes. (like that term).
I've attached a set of curves from K7QO.? The curve at the bottom is a power diode.? Note that there is not much change from about 5 V so higher voltages don't help much.
--
Chuck, W5USJ (ex K2OFN)
Point, Rains Co, TX? EM22cv
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Re: Measuring Resonant Frequency of Traps Newbies SSTV
Tangential note and thank you to Ray for enabling the "edit" feature for comments. Sure allows one ot revise embarrassing spelling errors and grammatical mistakes.
Never did understand why Chuck did not do that with the original QRP-tech list.
--
William, k6whp
--------------------
"Cheer up, things could get worse. So I cheered up and things got worse."
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Re: Measuring Resonant Frequency of Traps Newbies SSTV
Rob,
Understand that. I coined the term "Baofeng Tech" -- originally defamatory -- mainly because there were a number of guys on a local SoCal repeater system who occupied commute time talking on their Baofengs from their cars with an INSIDE duck resulting in those annoyingly weak signals. Add to the fact that a large percentages spewed inanities and basically babbled on and on. Some/most continued for years without matriculating to other aspects of the hobby. I since left the system to avoid further frustration.
In our day, Rob, we'd call them "lids".
The term as used in this context is much more noble. It seems that some folks are getting into amateur radio and actually developing a keen interest in things like HF and *gasp* even learning CW! Many are receptive to QRP. Its these hams I endeavor to assist.
We found a couple of them last year -- Ed, KM6TNT and Matt, KM6TOA -- who came out for the Zuni Loop FD effort and did a masterful job for so-called Baofeng hams. Both will be back this year and will be eager to work CW. They are among the finest I have met and, I am sure, will rocket past me in op capability.
Anyway, off to try out some of the suggestions offered in this thread.
Happy Christmas and New Year to all!
--
William, k6whp
--------------------
"Cheer up, things could get worse. So I cheered up and things got worse."
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NanoVNA for Network Measurements
This is one of the great tools now available to all?for working with? project that you pump and signal into or receive a signal from?and finding out what is really going on.? The 11, 12 ports can provide some significant data..8^) There are two versions to consider, the NanoVNA-H and the larger screen?NanoVNA-F Join this group and do diligent research to learn what it's all about.? To begin with, it will overwhelm your senses... [email protected]?? It would be a good idea to join before you buy your first one. The VNAs?have a fairly steep learning curve.?If a?VNA is new to you,?it will take some study, reading?messages from an international group, and reading all the instructions?posted in the group files. Have Fun... -- Chuck, W5USJ (ex K2OFN) Point, Rains Co, TX? EM22cv
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Re: Measuring Resonant Frequency of Traps Newbies SSTV
I don't know about you guys but when I first got
a Technician license 21 years ago (after passing 5WPM CW) and I
was finally allowed to use a 2 meter HT I
could not purchase a 2 meter HT for anything less
than $150.
That $150 was cost prohibitive for me back then.
Over time I observed a number of other hams who were in the same
financial position... raising kids... who could not justify
blowing $150 on an HT for the hobby.
BUT
now that BAOFENG UV5R costs around $30.......
it just seems to me that this 2 meter HT would be a great
stepping stone to indroduce newbies to the hobby of ham radio.
And the WLN and BAOFENG 888s 440 radios are even cheaper.
I pretty much live on a $15 HT now.
Just mind blowing that my first HT cost ten times as much as this
one I use now....
and
I had to drive 3 hours to go buy my first HT at HRO in Delaware.
SO
then what?
Newbie....?? FNG ....?? has an HT.....? and asks what else he can
do in the hobby... having JUST that one $30 radio.
?PSK31 .....HELLSHREIBER and anything else you want to blast out
of FLDIGI.... and SSTV and ? APRS .....
all work fine with BAOFENGs .....
teach them how to build an interface..... NOT BUY... an
interface....
and the hobby will no longer be a repeater hobby.
73 Rob KB3BYT
On 12/18/2019 08:01 PM, k6whp wrote:
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It's a
Military/Viet Nam Era thing. "F---ing New Guy" meaning the newest
arrival in a unit.
Also, many, many thanks for the great ideas. I think with the
availability and affordability of the antenna analyzers (starting
from ~$50 for the Cheap Chinese? ones) and the $20 component
checkers or the Chinese L/C meters, that's a viable solution and
can easily be argued as a "must have" for the Baofeng Techs who
want to branch out and actually learn about antenna and
electronics principles.?
I sure wish I has that kind of stuff when I started out as a
Novice in 1961!
Again, thank you all for the robust (and informative)
responses! And, by the way, thanks Ryan for the great forum.
It's really running great!
--
William, k6whp
--------------------
"Cheer up, things could get worse. So I cheered up and things got
worse."
|
Loading the clock outputs with 50 ohms (such as a 6db attenuator) will make crosstalk and phase noise much worse. Hence the discussion here of cheap 74ACT and 74LVC series buffers to drive a 50 ohm load. Hans reports the Si5351 based QCX does pretty good on phase noise, see the last paragraph here: ? ?? /g/qrptech/message/326Apparently much better than a traditional VFO. If you need better than that for some reason, SiLabs does sell parts that cost more than $1. Jerry
On Wed, Dec 18, 2019 at 02:08 PM, Bo, OZ2M wrote:
Hi
Yes, generally it is a good idea to make the mixer see a constant load vs frequency. So a 6 dB pad will provide a higher return loss than 3 dB will. But given that the output power from a single CLKx pin is ~11 dBm a 3 dB to 4 dB is all the headroom there is for a 7 dBm DBM.
For us radio amateurs spurious matters. To many a simple low pass filter following the Si5351A is fine – “Spectrum, you ask? I have added a LPF so everything is honky dory”. Harmonics are easy to do something about. But what about the receivers, that may be affected by bad phase noise and spurious? Karen, RA3APW, has documented his Si5351A spectrum findings here you can try to compare them with a different implementation like the RFzero: where cross-talk doesn’t see to be an issue either.
So just mounting a Si5351A on a piece of PCB doesn’t necessarily mean that it will be a good solution RF-wise. The Si5351A is a device designed for the digital domain where spurious is close to being irrelevant as long as it doesn’t affect the ability to lock/trigger on a stable signal, so jitter, i.e. phase noise, matters.
Bo
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Re: Measuring Resonant Frequency of Traps
It's a Military/Viet Nam Era thing. "F---ing New Guy" meaning the newest arrival in a unit.
Also, many, many thanks for the great ideas. I think with the availability and affordability of the antenna analyzers (starting from ~$50 for the Cheap Chinese? ones) and the $20 component checkers or the Chinese L/C meters, that's a viable solution and can easily be argued as a "must have" for the Baofeng Techs who want to branch out and actually learn about antenna and electronics principles.?
I sure wish I has that kind of stuff when I started out as a Novice in 1961!
Again, thank you all for the robust (and informative) responses! And, by the way, thanks Ryan for the great forum. It's really running great!
--
William, k6whp
--------------------
"Cheer up, things could get worse. So I cheered up and things got worse."
|
Re: Measuring Resonant Frequency of Traps
whats the FNG mean?
On 12/18/2019 04:12 PM, Eric KE6US
wrote:
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Did we miss the part where William explains
they are FNG Baofeng techs?
Eric KE6US
On 12/18/2019 1:02 PM, Jerry Gaffke
via Groups.Io wrote:
Or, obviously,
just a transmitter with an SWR meter (perhaps Diz's tandem
match).
But the single number representing SWR into an assumed 50 ohm
antenna system
is not nearly as informative as the two numbers for complex
impedance (resistance and capacitive/inductive reactance)
that the nanoVNA can tell you.
On Wed, Dec 18, 2019 at 11:40 AM, Jerry Gaffke wrote:
Perhaps an si5351 and Diz's Tandem Match would get
you most of the way there?
? ??
Useful for other things once the antenna is trimmed.
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Re: Measuring Resonant Frequency of Traps
NOTHING beats a real antenna analyzer.
Just my opinion.
I bought a used MFJ259 for $100 ....twenty years
ago and it has been THE "go to" tool for the local radio club
and
has been passed around so much it got the power
supply jack damaged and needs to be repaired.
So... when I recently learned about the nanoVNA
being able to to the same thing I use the MFJ259 for.....
hand craft HF antennas......
I jumped on that nanoVNA.... its "in the mail"....
so
I highly recommend that you get a couple guys to
chip in and buy the nanoVNA for around $50
if you can't afford one for yourself.
The MFJ259 ...and that line up ...?
are great tools but if you NEVER are going to
play with ALL the frequencies they off .... then why spend
another $400 on a tool you will never use.
The MFJ213 is the HF version... costs $230.
You KNOW we all would own these tools if they
ware not so expensive.
So check out the nanoVNA.
73 Rob KB3BYT
/18/2019 01:51 PM, k6whp wrote:
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Thought I'd
throw this out for the group. I got trapped [sorry!] into
schooling some "Baofeng Techs" (FNGs) who are interested in
getting into HF about building trap antennas. Of course, being
new, they do not have the luxuriant array of test equipment we
seem to stack up over the years so I wanted to suggest to them
ways they could construct traps and prove out the resulting
resonant frequencies of same.
They will be pointed to the appropriate theory, formulas, and
internet calculators to derive the component values, inductance,
number of turns, etc. but after they have built the traps, I
wanted to provide them with a crude but decent method of
determining the resonant frequency. (It would not do, after all,
to have them wind a 20m trap resonant at 16 MHz.)?
Assume they have a brand new transceiver, can afford a decent VSWR
meter, and can lay their hands on stuff like #47 panel lights,
LEDs, wire, coax, etc. and know how to solder. They know ought of
antenna analyzers, don't have a clue what a GDO is, and other
"desert island" stuff like that.
Appreciate any ideas.
--
William, k6whp
--------------------
"Cheer up, things could get worse. So I cheered up and things got
worse."
|
Hi
Yes, generally it is a good idea to make the mixer see a constant load vs frequency. So a 6 dB pad will provide a higher return loss than 3 dB will. But given that the output power from a single CLKx pin is ~11 dBm a 3 dB to 4 dB is all the headroom there is for a 7 dBm DBM.
For us radio amateurs spurious matters. To many a simple low pass filter following the Si5351A is fine – “Spectrum, you ask? I have added a LPF so everything is honky dory”. Harmonics are easy to do something about. But what about the receivers, that may be affected by bad phase noise and spurious? Karen, RA3APW, has documented his Si5351A spectrum findings here you can try to compare them with a different implementation like the RFzero: where cross-talk doesn’t see to be an issue either.
So just mounting a Si5351A on a piece of PCB doesn’t necessarily mean that it will be a good solution RF-wise. The Si5351A is a device designed for the digital domain where spurious is close to being irrelevant as long as it doesn’t affect the ability to lock/trigger on a stable signal, so jitter, i.e. phase noise, matters.
Bo
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Re: Measuring Resonant Frequency of Traps
A Millen Antenna Bridge will give you both the R and Xc of an antenna.
?
But a simple Heathkit Antenna Bridge will give you only the R of the antenna.
?
These things date WAY BACK!
?
And they have only PASSIVE? components!
?
Bob Macklin
K5MYJ
Seattle, Wa.
?
---
New Outlook Express and Windows Live Mail replacement - get it here:
? ?
?
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----- Original Message -----
Sent: 12/18/2019 1:12:20 PM
Subject: Re: [qrptech] Measuring Resonant Frequency of Traps
Did we miss the part where William explains they are FNG Baofeng techs?
Eric KE6US
On 12/18/2019 1:02 PM, Jerry Gaffke via Groups.Io wrote:
Or, obviously, just a transmitter with an SWR meter (perhaps Diz's tandem match).
But the single number representing SWR into an assumed 50 ohm antenna system
is not nearly as informative as the two numbers for complex impedance (resistance and capacitive/inductive reactance)
that the nanoVNA can tell you.
On Wed, Dec 18, 2019 at 11:40 AM, Jerry Gaffke wrote:
Perhaps an si5351 and Diz's Tandem Match would get you most of the way there?
? ??
Useful for other things once the antenna is trimmed.
|
Re: Measuring Resonant Frequency of Traps
Some newer transceivers, like the Icom IC-7300, include a graphical SWR plot function. Put a dummy load on the other end of the trap and have the radio show you the swr plot. That might help some. Mike M.? KU4QO
On Wed, Dec 18, 2019 at 1:51 PM k6whp < k6whp@...> wrote: Thought I'd throw this out for the group. I got trapped [sorry!] into schooling some "Baofeng Techs" (FNGs) who are interested in getting into HF about building trap antennas. Of course, being new, they do not have the luxuriant array of test equipment we seem to stack up over the years so I wanted to suggest to them ways they could construct traps and prove out the resulting resonant frequencies of same.
They will be pointed to the appropriate theory, formulas, and internet calculators to derive the component values, inductance, number of turns, etc. but after they have built the traps, I wanted to provide them with a crude but decent method of determining the resonant frequency. (It would not do, after all, to have them wind a 20m trap resonant at 16 MHz.)?
Assume they have a brand new transceiver, can afford a decent VSWR meter, and can lay their hands on stuff like #47 panel lights, LEDs, wire, coax, etc. and know how to solder. They know ought of antenna analyzers, don't have a clue what a GDO is, and other "desert island" stuff like that.
Appreciate any ideas.
--
William, k6whp
--------------------
"Cheer up, things could get worse. So I cheered up and things got worse."
|
Re: Measuring Resonant Frequency of Traps
Did we miss the part where William explains they
are FNG Baofeng techs?
Eric KE6US
On 12/18/2019 1:02 PM, Jerry Gaffke via
Groups.Io wrote:
toggle quoted message
Show quoted text
Or, obviously, just
a transmitter with an SWR meter (perhaps Diz's tandem match).
But the single number representing SWR into an assumed 50 ohm
antenna system
is not nearly as informative as the two numbers for complex
impedance (resistance and capacitive/inductive reactance)
that the nanoVNA can tell you.
On Wed, Dec 18, 2019 at 11:40 AM, Jerry Gaffke wrote:
Perhaps an si5351 and Diz's Tandem Match would get you
most of the way there?
? ??
Useful for other things once the antenna is trimmed.
|
Re: Measuring Resonant Frequency of Traps
Or, obviously, just a transmitter with an SWR meter (perhaps Diz's tandem match).
But the single number representing SWR into an assumed 50 ohm antenna system
is not nearly as informative as the two numbers for complex impedance (resistance and capacitive/inductive reactance)
that the nanoVNA can tell you.
toggle quoted message
Show quoted text
On Wed, Dec 18, 2019 at 11:40 AM, Jerry Gaffke wrote:
Perhaps an si5351 and Diz's Tandem Match would get you most of the way there?
? ??
Useful for other things once the antenna is trimmed.
|
Re: Measuring Resonant Frequency of Traps
Might not be a good idea to test the traps in isolation.
The remainder of the antenna system can affect resonance.
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Dale Hardin KS4NS
Chuck Carpenter
k6whp
Bo, OZ2M