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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Show quoted text
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.
|
Re: Measuring Resonant Frequency of Traps
Google "nanoVNA",? $50 for a vna good from khz to ghz.
Display is teensy and thumbswitch is cranky, but performance is exceptional.
Newer versions are coming out.
Non-trivial for the neophyte, but extremely educational.
The antuino from hfsignals would also be fine as an antenna analyzer.
Could also serve as a sort-of spectrum analyzer if you can live with the images and harmonics, it has no front end filtering.
Either one should prove a lot more interesting than spending $300 on an MFJ-259?
Anybody have other suggestions on what's new in this sort of gear?
Comments on what works?
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.
Jerry, KE7ER
|
Re: Measuring Resonant Frequency of Traps
Connect the parallel resonant circuit in line
with their transceiver input and tune for a null or connect it
across the input and tune for a peak. You could also have them
reconfigure it as a series resonant circuit, test it in the same
way and learn why traps are parallel resonant, not series
resonant.
For an unforgettable lifelong lesson, albeit an
expensive one, let them transmit into it. OK, maybe just a
strong warning not to ever do that would be in order.
Eric KE6US
On 12/18/2019 10:51 AM, k6whp wrote:
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Show quoted text
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
Although it may qualify as "fancy" equipment for the "desert island" scenario, an antenna analyzer can easily show you the SWR of a filter at a given frequency, and you can manually plot a curve if you like, or else just watch the values as you go up/down in frequency to eyeball it. I do this for building/tuning band pass filters: 50ohm load on one end, analyzer on the other. Works great.
On Wed, Dec 18, 2019 at 10:51 AM 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."
-- Ryan Flowers W7RLF
https://miscdotgeek.com
|
Measuring Resonant Frequency of Traps
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."
|
If the load is of high enough impedance, you might get by without the push-pull pair.
So I might try first without Q72,Q73, drive your tube rig over a twisted wire pair (or coax)
from the junction between Q71-collector and R75.?
Remember that we had earlier shorted across those two diodes.
Others are more than welcome to chime in, tell us why that won't work.
At least if this circuit smokes, won't be an expensive loss.
Jerry
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On Wed, Dec 18, 2019 at 10:05 AM, Don Richards wrote:
Jerry
I like the idea of the ubitx audio stage. I should have all the parts on hand to give that a try.?
Thanks!
73 Don ve3ids
|
Jerry I like the idea of the ubitx audio stage. I should have all the parts on hand to give that a try.? Thanks! 73 Don ve3ids
On Wed., Dec. 18, 2019, 12:13 p.m. Jerry Gaffke via Groups.Io, <jgaffke= [email protected]> wrote: It is sobering to think how they got by with such simple gear in say, the late 1920's.
Amazing that a single tube regenerative receiver works at all, let alone well enough to use on the ham bands.
A lot of those ham's used that single tube for transmitting also, a few of them on purpose.
A modern DSP rig could have a billion transistors.
Using a perfectly good QRP rig to go from 3v pk-pk to a 10 volt signal would strike them as preposterous.
If Don wants to tinker, a good starting point might be the uBitx v4 push-pull audio amp:
? ??
Start with everything between VOL-M, and SPK, remove C78, short out R71, change caps C72, C73, C74 to 0.1uF,?
We don't need this to be linear, so remove D15 and D16, short across R76 and R77.
(When I say short across", I mean replace that part with a wire.)?
From there it might just work, or could take a few minutes (or months) of learning why it doesn't work.
I have no idea what kind of load Don is actually driving.
The 2n2222a and 2n2907a would be a beefier choice for the transistors.
Jim would approve.
That circuit didn't work very well as an audio amp in the uBitx, v5 went to an LM386.
Here's some food for thought regarding a good simple audio amp, second schematic down:??
? ??
Similar to the uBitx audio amp, except uses an IC as a driver.
That IC would be too slow for use at radio frequencies.
Jerry, KE7ER
On Wed, Dec 18, 2019 at 08:06 AM, Eric KE6US wrote:
It would work fine. I used my K2 as a VFO for a Drake 2NT until I could get something built for it.
We might overthink things in the digital age. They used to be a lot simpler, and the still could be.
Eric kE6US
|
I like the notion of two 74ACT04 gates in push pull.
But wonder what kind of trouble you could get into using that to drive a transformer.
Whenever I see a full description of the design process for a circuit with magnetics,
it seems I always learn something new.?
To use inverters in push-pull, the logical thing would be to invert the original signal with one gate,
then feed the original and the inverted signal into two other inverter gates.
However, prop delay through one gate is spec'd to be somewhere between 1 and 9 ns.
A better choice might be 74ACT86 ex-or gates both driven from the same signal,
the second input held high on one gate and shorted to ground on the other.
Supply sequencing can definitely cause trouble.
Some parts are designed to survive indefinitely, regardless of supply sequencing.
Many parts will live through a millisecond or so of poorly thought out sequencing.
At work, we often had digital designs with a half dozen different supplies.
A single FPGA might have that many.
It was something to worry about, but we generally had plenty of other problems to solve that were more pressing.
Jerry, KE7ER
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On Wed, Dec 18, 2019 at 04:55 AM, Steven Dick wrote:
Something to keep in mind in circuits that use multiple power supplies is power sequencing:? It is important that the 5V comes on before the 3.3V and turns off after the 3.3V when the 3.3V turns off.? Otherwise you can drive the 5V unpowered device from the 3.3V driving chip.? If the 3.3V driving chip can supply a hefty amount of current, you can? possibly damage the input circuitry of the 5V powered device by forward biasing its protection diode if it has one.? That protection diode may see more current than it is designed to handle. Depending on the particular 5V device, it may not immediately fail but can ultimately fail with repeated power sequencing at turn on or turn off.? A possible safety measure is to put a small Schottky diode between the +5V and +3.3V rails in the direction such that the 3.3V supply pulls up the 5V rail if unpowered, until the 5V supply kicks in and turns off that diode.? If the 3.3V supply is derived from the 5V supply, that is normally not a problem. But if the 5V and 3.3V supplies are totally independent, that problem can easily happen. The input clamp current for the 74ACT family has a clamp diode which is pretty hefty (current rating of 20mA) so it’s probably not a problem for the 74ACT chip, but you are momentarily shorting the output of the SI5351 at power up if there is a power sequence problem.
I haven’t tried it myself but if you need a larger voltage than that provided by a single +5V buffer or paralleled buffers, you can wire up the 74ACT04N? to generate a true and complement output.? A.C. couple them to a 1:1 RF transformer to get double the output or 10 volts peak to peak.? If you need more than 10 volts and are driving a high impedance load, then increase the turns ratio to 2 to 1 which will provide 20 volts peak to peak.? You can make your own one to one transformer with a low cost toroid and bifilar winding. Drive one winding with the true and complement outputs. The other winding is the secondary going to the load. You can use trifilar winding for two to 1 turns ratio. Drive one winding with the true and complement outputs.? Put the other two windings in series aiding for the secondary.?? Winding them bifilar or trifilar improves the bandwidth.
|
It is sobering to think how they got by with such simple gear in say, the late 1920's.
Amazing that a single tube regenerative receiver works at all, let alone well enough to use on the ham bands.
A lot of those ham's used that single tube for transmitting also, a few of them on purpose.
A modern DSP rig could have a billion transistors.
Using a perfectly good QRP rig to go from 3v pk-pk to a 10 volt signal would strike them as preposterous.
If Don wants to tinker, a good starting point might be the uBitx v4 push-pull audio amp:
? ??
Start with everything between VOL-M, and SPK, remove C78, short out R71, change caps C72, C73, C74 to 0.1uF,?
We don't need this to be linear, so remove D15 and D16, short across R76 and R77.
(When I say short across", I mean replace that part with a wire.)?
From there it might just work, or could take a few minutes (or months) of learning why it doesn't work.
I have no idea what kind of load Don is actually driving.
The 2n2222a and 2n2907a would be a beefier choice for the transistors.
Jim would approve.
That circuit didn't work very well as an audio amp in the uBitx, v5 went to an LM386.
Here's some food for thought regarding a good simple audio amp, second schematic down:??
? ??
Similar to the uBitx audio amp, except uses an IC as a driver.
That IC would be too slow for use at radio frequencies.
Jerry, KE7ER
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On Wed, Dec 18, 2019 at 08:06 AM, Eric KE6US wrote:
It would work fine. I used my K2 as a VFO for a Drake 2NT until I could get something built for it.
We might overthink things in the digital age. They used to be a lot simpler, and the still could be.
Eric kE6US
|
It would work fine. I used my K2 as a VFO for a Drake 2NT until I
could get something built for it.
We might overthink things in the digital age. They used to be a
lot simpler, and the still could be.
Eric kE6US
On 12/17/2019 7:42 PM, Jerry Gaffke via
Groups.Io wrote:
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Do you have QRP
transmitter lying about capable of at least 2 Watts?
Drive that QRP transmitter with the Si5351,
put a 50 ohm dummy load on the QRP transmitter so you don't blow
it up,
and run coax from that dummy load into your vacuum tube
transmitter.
A two watt transmitter into 50 ohms is? squareroot(2*50) = 10
volts RMS?
If it's more than two watts, you could bring it down by a special
resistive divider dummy load.
Might work.
Jerry
On Tue, Dec 17, 2019 at 06:28 PM, Don Richards wrote:
Jerry
Thanks for the info. I need about 10 volts. What are your
thoughts on this?
?
?
73 Don ve3ids
|
Something to keep in mind in circuits that use multiple power supplies is
power sequencing:? It is important that the 5V comes on before the 3.3V and
turns off after the 3.3V when the 3.3V turns off.? Otherwise you can drive
the 5V unpowered device from the 3.3V driving chip.? If the 3.3V driving
chip can supply a hefty amount of current, you can? possibly damage the
input circuitry of the 5V powered device by forward biasing its protection diode
if it has one.? That protection diode may see more current than it is
designed to handle. Depending on the particular 5V device, it may not
immediately fail but can ultimately fail with repeated power sequencing at turn
on or turn off.? A possible safety measure is to put a small Schottky diode
between the +5V and +3.3V rails in the direction such that the 3.3V supply pulls
up the 5V rail if unpowered, until the 5V supply kicks in and turns off that
diode.? If the 3.3V supply is derived from the 5V supply, that is normally
not a problem. But if the 5V and 3.3V supplies are totally independent, that
problem can easily happen. The input clamp current for the 74ACT family has a
clamp diode which is pretty hefty (current rating of 20mA) so it’s probably not
a problem for the 74ACT chip, but you are momentarily shorting the output of the
SI5351 at power up if there is a power sequence problem.
I haven’t tried
it myself but if you need a larger voltage than that provided by a single +5V
buffer or paralleled buffers, you can wire up the 74ACT04N? to generate a
true and complement output.? A.C. couple them to a 1:1 RF transformer to
get double the output or 10 volts peak to peak.? If you need more than 10
volts and are driving a high impedance load, then increase the turns ratio to 2
to 1 which will provide 20 volts peak to peak.? You can make your own one
to one transformer with a low cost toroid and bifilar winding. Drive one winding
with the true and complement outputs. The other winding is the secondary going
to the load. You can use trifilar winding for two to 1 turns ratio. Drive one
winding with the true and complement outputs.? Put the other two windings
in series aiding for the secondary.?? Winding them bifilar or trifilar
improves the bandwidth.
-Steve K1RF
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Sent: Tuesday, December 17, 2019 9:05 PM
Subject: Re: [qrptech] Si5351 output power
?
Maybe
this 74ACT04N, $0.50 plus $10 shipping: ??? Ground
pin 7 with a very short wire (or just bend the pin down to where you can solder
it to a bare copper covered PC board) Also ground the unused inputs at pins
3,5,9,11,13 Put 5.0 volts on pin 14, and add a 0.1uF cap from that pin to
ground, keep the capacitor wires short. Drive the Si5351 output into pin 1
using a twisted wire pair of that signal plus ground. Try driving your
transmitter with the 5.0 volt square wave coming out of pin 2 using another
twisted wire pair. Might work, especially if it almost works with the 3.3
volts from an Si5351. The 74ACT family of parts is unusual in that it is
CMOS but tries to be compatible with old school TTL, so the input threshold
voltage is kept around 1.5 volts regardless of the power supply voltage. That
allows us to drive this part directly from the 3.3 volt Si5351, even when this
part is powered from 5 volts. And at 24ma, the output buffers are relatively
hefty. A bit more output could be had by bumping the supply up as high as 5.5
volts, beyond that is not recommended. If you needed more current available
at the output than 24ma (I doubt it) then multiple inverters could be wired in
parallel. A good idea to ground the inputs as they are high impedance and
might decide to float into the input transition region, at which point the
part can get hot and possibly oscillate. If you need more than a 5v
square wave, an easy pre-packaged solution might be a comparator that can
deal with perhaps a 12v power supply.? But try this first. Jerry,
KE7ER On Tue, Dec 17, 2019 at 01:07 PM, Don Richards wrote:
On a related topic, I built a vfo with a nano and a 5351 to replace the
vfo in a tube rig but I need more voltage to drive it. It will operate the
receiver but is just on the edge for the TX. It will only muster half power at
best. I built the two transistor circuit that is commonly found online but it
doesn't work that well. Does anyone have anything better? Since it is a square
wave, would some flip flop chip work and go rail to rail?
Just thinking out loud
?
73 Don ve3ids
|
Hi all
Loading an Si5351A output at 50-ohms also affects phase noise. I did a study of Si5351A phase noise, particularly in relation to the QCX CW transceiver . One of the motivations for the experiments were suggestions I had received, that more supply line filtering would improve the phase noise of the QCX synthesizer. In the end I found supply cleanliness is certainly important but, in regard to the QCX, the QCX performance is already good and I could not find any way to further improve it.?
Anyway - another conclusion of the experiments was that with a 50-ohm load the phase noise is significantly degraded compared to a higher impedance load; this can be somewhat remediated by using a DC blocking capacitor.?
Application is important: what level of performance is desired depends on the application. If you need highest performance then ideally use a higher impedance load, don't load the Si5351A outputs with 50-ohms. If you must, then be sure to use a capacitor in series with the load.?
Avoiding cross-talk between outputs is another reason to use high impedance loads, in applications where you will be using multiple Si5351A outputs and need low crosstalk.
73 Hans G0UPL? ?
|
If you read the datasheet, the Si5351 claims to have a 50 ohm output.
But yes, it is primarily designed to replace cheap 4 pin crystal oscillators.
Jerry
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On Tue, Dec 17, 2019 at 08:24 PM, Bob Clarke wrote:
It’s a clock generator and was designed to drive a logical load, that is, a CMOS or TTL input, and definitely not a 50 ohm resistance. The first rule in a situation like this is to *read* the data sheet and see what the actual spec is, then add an appropriate buffer. You can go the elegant route with an emitter follower or use a bunch of inverters in parallel.?
?
|
Re: What level math is in the RF design books?
Good news:? Algebra for designing and biasing bipolar circuits.
Not so good news:? Partial differential equations for biasing FET circuits, though I’d probably just copy an oscillator circuit rather than design one from scratch.
In W7ZOI’s books just algebra, I think. Generally speaking approximations are used for calculating collector current. It’s all good, don’t worry about the math. I had hard core semiconductor physics in school and never really used it.?
Bob, N1RC
What level of math course would I need to study to learn how to comprehend the equations presented in
design books like Introduction to Radio Frequency Design?? by? W7ZOI.
I have been tinkering with circuits from these books for 50 years but never really learned what is in the math.
There are all sorts of online math course now so.....
What level of math class would teach this gobbledygoop?
and
Do any of you? ACTUALLY use this level of math to build radios or is the math only used by
the guys designing the transistors????
73 Rob KB3BYT
-- Bob Clarke
M: 978.337.2720
|
Bo, OZ2M
k6whp
Don VE3IDS
Bob N1RC