Re: DC blocking cap between souncard and ubitc mic input.
#ft8
#ubitx
0.1uF at 300hz has a reactance around 5000ohm, at 3Khz 500ohm, so it acts as a sort of audio high pass filter. If the cap has a higher capacitance the audio response is flatter.
Il 04/mar/2019 19:15, "Joe Puma" < kd2nfc@...> ha scritto: The easydigi does have this blocking cap. .1uf
Joe KD2NFC? So things are actually worse when using a transformer to isolate the mic line? So things like the easy-digi etc. make things worse? this was not my experience at all. before using a transformer, i could not sustain the audio connection between my (horrible) single audio jack on my handheld PC, but after i could without issue.
So, it's possible that using easy-digi or a transformer is shunting the voltage on the mic line to ground, which could cause all manner of strange problems with the uBitx? Is this correct?
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Filters...
Part of the problem with using filters, or additional filters, is that some of the undesired
signals are tunable.? They are not always on the same frequency, depending on where
the VFO frequency is set.? This pretty much requires that these filters either be for a single
band, or in the IF region where frequencies are stable.?
There is a way to add a parallel capacitor to a pi-type filter to cause a steep notch
at some other frequency.? N7VE did that very effectively in design of the BITX20A and
BITX17A.? Others implemented the same idea with their BITX40A versions.? I have not
seen that done or discussed for later designs.? Of course this gets us back to the spurs
and harmonics being tunable and not on a set frequency.? You can add the notching
capacitor but it will be for a specific frequency.? Filter bandwidth versus depth can be
changed by adding resistance to degrade the filter.? This makes the filters broader but
less effective.?
If you want to play with filter characteristics it is possible to model them in LTSpice. The models will not be real-world because of distributed capacitance and inductance,
but they will be fairly close.? If you know the amount of extraneous capacitance and
inductance presented to your filters you can enter that as well in the Spice model to
get quite accurate results.?
Filter characteristics and application is an ongoing discussion point.? We could start a
#hashtag for consolidating filter related discussion but there are so many different
filters, and different places to apply them that the consolidation would probably be
ineffective.
Arv? K7HKL _._
On Mon, Mar 4, 2019 at 1:25 PM Adrian Chadd < adrian@...> wrote: Well, where are the harmonics showing up? :)
-adrian
So, perhaps a dumb question or maybe two .., but "Why the continued instance on using low-pass filters ...Wouldn't some band-pass filters make more sense??
Jim
On Monday, March 4, 2019, 12:15:41 PM PST, Jerry Gaffke via Groups.Io <jgaffke= [email protected]> wrote:
As I said in post 66008: > Allisons extra filters would fix that, at the cost of considerable complication. On Mon, Mar 4, 2019 at 12:03 PM, ajparent1/KB1GMX wrote:
o fix this more fully:
Switchable filters to replace? the 33mhz? existing one L1-4.
for the 3.5- 5mhz range a low pass filter with cutoff of 6mhz
for the 7- 10mhz range a low pass filter with cutoff of 11mhz
for the 11- 19mhz range a low pass filter with cutoff of 20mhz
for the 20- 29.9mhz range a High pass filter with cutoff of 20mhz
***Note for this range that helps but a band pass for 21mhz and a
wide band pass for 24-29mhz would also be a better way (clean ssb).
Either way 4 to 5 filters greatly clean up signals.
The 33mhz filter delete it.
Why would this work?? The RF source tends to be biased toward greater third
harmonic for CW so putting effort into the second harmonic reduction for a filter
is not required.? The result is a modest 15db reduction of third harmonic and
spurs into the PA would clean up many if not all of the offending signals.?
Good filters will with good switching can achieve more.
Since the work is being down at low power levels (sub 1 milliwatt) SMD inductors
and capacitors will be adequate.? Switching can be done with diodes or relays.
The problem is space and simply doing it.? The board space is limited however
the underside is totally unused.
Allison
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A bandpass filter that gives flat response across all of 80m (let alone 80m+60m both)?
would be more difficult to implement than a low pass filter.
Though a bandpass filter if done well could be better, in that it would reject some spurs below the operating frequency.
Jerry
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On Mon, Mar 4, 2019 at 12:24 PM, Adrian Chadd wrote:
Well, where are the harmonics showing up? :)
-adrian
?
toggle quoted mes
?
So, perhaps a dumb question or maybe two .., but "Why the continued instance on using low-pass filters ...Wouldn't some band-pass filters make more sense??
Jim
?
On Monday, March 4, 2019, 12:15:41 PM PST, Jerry Gaffke via Groups.Io <jgaffke= [email protected]> wrote:
As I said in post 66008:
> Allisons extra filters would fix that, at the cost of considerable complication.
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if its the common 100prr-6 (6 terminals on the back):
the A and B termianls are transistors to ground and are used.
Ground is ground (0V) termial
Black and brown to the A and B terminals? (reverse if the rotation direction is backward)
5V from raduino 5V reg to the leds (Vcc? terminal)
One note I used V4.3 code with my mods and it worked well.? Some codes for the
Raduino are slow and if you rotate the encoder quickly it will not keep up.
Allison
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Oliver,
Does your rotary encoder put out 5v pulses on an A and a B channel when you spin the dial?
If yours is like the industrial service rotary encoder I plan to install and puts out 5-volt pulses from an A and B terminal, then it's a bit different from the stock encoder.? The stock encoder basically grounds the black (A) and brown (B) lines in "pulse-like" fashion while turning the knob. What we have to do is convert our encoders from a pulsed-output of 5v signals, to perform the pulsed-grounding of live signal lines delivered to it from the radio.
I might suggest taking the brown wire from the Raduino plug and connect it to the Source leg of a 2N7000. Connect the Drain to earth (yellow). The leg of the transistor that remains, the Gate, connects to one output or the other of your new encoder. Now, repeat this transistor make-up for the Raduino's black wire using a second 2N7000.? Connect that equation up to the other output terminal of your encoder.? I don't know if A=A and B=B on your encoder compared to the original, though you'll find out.
Doing this, your encoder's 5v pulses will "instruct" these two FET transistors to momentarily short out the original Raduino signal lines to earth in the same way that the original encoder device momentarily or repeatedly shorts out the black and brown for tuning or for function-selections. In other words, we've reversed the new encoder's output logic to match the old one's logic so that your uBitx sees what it expects to see [and does what it expects it to do].
If tuning goes backward, reverse the "B" and the "A" wires.?And, obviously, remember to? install a separate momentary push button between the red and yellow wires before you end up needing that for radio operating functions in the future
73,
Ted
On Mon, Mar 4, 2019 at 3:50, Olivier Grand <olilou1961@...> wrote: Hello All I have one (5 volt) of these but I don't know how to wire it on my uBitx v5 please help ! Many thanks. 73' Olivier Le?sam. 2 mars 2019 ¨¤?22:15, ajparent1/KB1GMX < kb1gmx@...> a ¨¦crit?: I have two of those and its 5v for the leds and it works well.
Its a lot more durable than the usual cheapie encoder but needs a lot of
panel area making it tough for some cases.
Allison
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Re: change keyer type on nextion
Anyone happen to have a version 3 hmi for 3.5"? Thx.
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Re: DC blocking cap between souncard and ubitc mic input.
#ft8
#ubitx
Awesome, it didn¡¯t hit me at first. I just grabbed two off eBay for $11 for both. I have parts I was going to use on interfaces, transformers, optocouplers, the easydigi has all you need. I¡¯ve known about easydigi for a while but now that I¡¯m digging deeper in EE I understand what all the parts do in the circuit. Even on antenna lines. The DC cap is very necessary when doing bias t on receive antennas. You guys taught me so much lol ;)
Joe
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On Mar 4, 2019, at 3:20 PM, Gordon Gibby < ggibby@...> wrote:
Joe Puma, yes that is most likely the purpose. ?Been there, done that, learned a thing.?
On Mar 4, 2019, at 18:36, Joe Puma < kd2nfc@...> wrote:
Gordon, I¡¯ve been using the easydigi¡¯s, is that the purpose of cap in between both mic and audio connections to radio?
Joe
On Mar 4, 2019, at 10:51 AM, Gordon Gibby < ggibby@...> wrote:
Transformer Makes it worse. ?
Do not short the dc bias voltage¡ªlikely it will take input transistor or op amp to un-usable ?bias?
On Mar 4, 2019, at 17:27, Joe Puma < kd2nfc@...> wrote:
could something like a 600:600 transformer solve that issue too? I¡¯ve ?been putting them between all my audio and mic I/O¡¯s when connecting to pc/soundcard
Joe
kd2nfc
On Mar 4, 2019, at 10:24 AM, Gordon Gibby < ggibby@...> wrote:
We made the mistake of not dc blocking mic inputs of some commercial vhf rigs ¡ª-bad distortion in input stage?
On Mar 4, 2019, at 16:41, Praba Karan < vu3dxr@...> wrote:
Is dc blocking capacitor necessary between sound card audio output and mic input of ubitx during digital modes?. I made a direct connection between above without DC blocking cap. Though? my ubitx received so many, very few logged my
cq calls as per pskreporter. Any advices?
|
Well, where are the harmonics showing up? :)
-adrian
So, perhaps a dumb question or maybe two .., but "Why the continued instance on using low-pass filters ...Wouldn't some band-pass filters make more sense??
Jim
On Monday, March 4, 2019, 12:15:41 PM PST, Jerry Gaffke via Groups.Io <jgaffke= [email protected]> wrote:
As I said in post 66008: > Allisons extra filters would fix that, at the cost of considerable complication. On Mon, Mar 4, 2019 at 12:03 PM, ajparent1/KB1GMX wrote:
o fix this more fully:
Switchable filters to replace? the 33mhz? existing one L1-4.
for the 3.5- 5mhz range a low pass filter with cutoff of 6mhz
for the 7- 10mhz range a low pass filter with cutoff of 11mhz
for the 11- 19mhz range a low pass filter with cutoff of 20mhz
for the 20- 29.9mhz range a High pass filter with cutoff of 20mhz
***Note for this range that helps but a band pass for 21mhz and a
wide band pass for 24-29mhz would also be a better way (clean ssb).
Either way 4 to 5 filters greatly clean up signals.
The 33mhz filter delete it.
Why would this work?? The RF source tends to be biased toward greater third
harmonic for CW so putting effort into the second harmonic reduction for a filter
is not required.? The result is a modest 15db reduction of third harmonic and
spurs into the PA would clean up many if not all of the offending signals.?
Good filters will with good switching can achieve more.
Since the work is being down at low power levels (sub 1 milliwatt) SMD inductors
and capacitors will be adequate.? Switching can be done with diodes or relays.
The problem is space and simply doing it.? The board space is limited however
the underside is totally unused.
Allison
|
So, perhaps a dumb question or maybe two .., but "Why the continued instance on using low-pass filters ...Wouldn't some band-pass filters make more sense??
Jim
On Monday, March 4, 2019, 12:15:41 PM PST, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
As I said in post 66008:
> Allisons extra filters would fix that, at the cost of considerable complication.
On Mon, Mar 4, 2019 at 12:03 PM, ajparent1/KB1GMX wrote:
o fix this more fully:
Switchable filters to replace? the 33mhz? existing one L1-4.
for the 3.5- 5mhz range a low pass filter with cutoff of 6mhz
for the 7- 10mhz range a low pass filter with cutoff of 11mhz
for the 11- 19mhz range a low pass filter with cutoff of 20mhz
for the 20- 29.9mhz range a High pass filter with cutoff of 20mhz
***Note for this range that helps but a band pass for 21mhz and a
wide band pass for 24-29mhz would also be a better way (clean ssb).
Either way 4 to 5 filters greatly clean up signals.
The 33mhz filter delete it.
Why would this work?? The RF source tends to be biased toward greater third
harmonic for CW so putting effort into the second harmonic reduction for a filter
is not required.? The result is a modest 15db reduction of third harmonic and
spurs into the PA would clean up many if not all of the offending signals.?
Good filters will with good switching can achieve more.
Since the work is being down at low power levels (sub 1 milliwatt) SMD inductors
and capacitors will be adequate.? Switching can be done with diodes or relays.
The problem is space and simply doing it.? The board space is limited however
the underside is totally unused.
Allison
|
Re: DC blocking cap between souncard and ubitc mic input.
#ft8
#ubitx
Joe Puma, yes that is most likely the purpose. ?Been there, done that, learned a thing.?
On Mar 4, 2019, at 18:36, Joe Puma < kd2nfc@...> wrote:
toggle quoted message
Show quoted text
Gordon, I¡¯ve been using the easydigi¡¯s, is that the purpose of cap in between both mic and audio connections to radio?
Joe
On Mar 4, 2019, at 10:51 AM, Gordon Gibby < ggibby@...> wrote:
Transformer Makes it worse. ?
Do not short the dc bias voltage¡ªlikely it will take input transistor or op amp to un-usable ?bias?
On Mar 4, 2019, at 17:27, Joe Puma < kd2nfc@...> wrote:
could something like a 600:600 transformer solve that issue too? I¡¯ve ?been putting them between all my audio and mic I/O¡¯s when connecting to pc/soundcard
Joe
kd2nfc
On Mar 4, 2019, at 10:24 AM, Gordon Gibby < ggibby@...> wrote:
We made the mistake of not dc blocking mic inputs of some commercial vhf rigs ¡ª-bad distortion in input stage?
On Mar 4, 2019, at 16:41, Praba Karan < vu3dxr@...> wrote:
Is dc blocking capacitor necessary between sound card audio output and mic input of ubitx during digital modes?. I made a direct connection between above without DC blocking cap. Though? my ubitx received so many, very few logged my
cq calls as per pskreporter. Any advices?
|
As I said in post 66008:
> Allisons extra filters would fix that, at the cost of considerable complication.
toggle quoted message
Show quoted text
On Mon, Mar 4, 2019 at 12:03 PM, ajparent1/KB1GMX wrote:
o fix this more fully:
Switchable filters to replace? the 33mhz? existing one L1-4.
for the 3.5- 5mhz range a low pass filter with cutoff of 6mhz
for the 7- 10mhz range a low pass filter with cutoff of 11mhz
for the 11- 19mhz range a low pass filter with cutoff of 20mhz
for the 20- 29.9mhz range a High pass filter with cutoff of 20mhz
***Note for this range that helps but a band pass for 21mhz and a
wide band pass for 24-29mhz would also be a better way (clean ssb).
Either way 4 to 5 filters greatly clean up signals.
The 33mhz filter delete it.
Why would this work?? The RF source tends to be biased toward greater third
harmonic for CW so putting effort into the second harmonic reduction for a filter
is not required.? The result is a modest 15db reduction of third harmonic and
spurs into the PA would clean up many if not all of the offending signals.?
Good filters will with good switching can achieve more.
Since the work is being down at low power levels (sub 1 milliwatt) SMD inductors
and capacitors will be adequate.? Switching can be done with diodes or relays.
The problem is space and simply doing it.? The board space is limited however
the underside is totally unused.
Allison
|
Allison,
Are you referring to my suggestion of unbalancing the D3,D4 mixer,? CLK2=VFO, CLK1=45mhz, CLK0=dead??
Given the 45mhz crystal filter, there should then be only 45mhz energy present going into the D1,D2 mixer signal port.
And if that 45mhz sine wave is of low enough level, the primary product out of the D1,D2 mixer will?
be a sine wave at the transmit frequency.? ?
Plus some higher frequency stuff that gets stripped out by the 30mhz LPF.
And a bunch of crud from secondary mixer products and harmonics in the 45mhz IF and coupling from the PA.
But by unbalancing D3,D4 for CW transmit, we should get a CW signal that's as clean as SSB with regard to harmonics.
And be cleaner and simpler than messing with injecting an audio tone.
Jerry, KE7ER
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On Mon, Mar 4, 2019 at 11:48 AM, ajparent1/KB1GMX wrote:
The problem is the source is square and the DBM is being used for a switch.
That means the output is square.? AS to CW it works better than the old pump
in a tone and can be clean with the exception of managing harmonics.
In the old days and even now the tube rigs with SI5351 as a synthetic crystal
is clean, why?? Tubes are not fast they make lousy square waves even when
fed them.? that and many of the radios have tuned circuits before the final and
the output is tuned.? OFten if you qsy across them band touching up the tuning
is required.? ?That is what selectivity and tuning does for us and too us.
Modern radios are wide band amps that will make efforts to reproduce what
they were fed.? So the basic solution is still, filters, lacking that, a very clean
source.? Alas the uBitx has a square wave source and no way to clean up
before the amp, a hole is there to fill.
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to fix this more fully:
Switchable filters to replace? the 33mhz? existing one L1-4.
for the 3.5- 5mhz range a low pass filter with cutoff of 6mhz
for the 7- 10mhz range a low pass filter with cutoff of 11mhz
for the 11- 19mhz range a low pass filter with cutoff of 20mhz
for the 20- 29.9mhz range a High pass filter with cutoff of 20mhz
***Note for this range that helps but a band pass for 21mhz and a
wide band pass for 24-29mhz would also be a better way (clean ssb).
Either way 4 to 5 filters greatly clean up signals.
The 33mhz filter delete it.
Why would this work?? The RF source tends to be biased toward greater third
harmonic for CW so putting effort into the second harmonic reduction for a filter
is not required.? The result is a modest 15db reduction of third harmonic and
spurs into the PA would clean up many if not all of the offending signals.?
Good filters will with good switching can achieve more.
Since the work is being down at low power levels (sub 1 milliwatt) SMD inductors
and capacitors will be adequate.? Switching can be done with diodes or relays.
The problem is space and simply doing it.? The board space is limited however
the underside is totally unused.
Allison
|
Jerry,
The problem is the source is square and the DBM is being used for a switch.
That means the output is square.? AS to CW it works better than the old pump
in a tone and can be clean with the exception of managing harmonics.
In the old days and even now the tube rigs with SI5351 as a synthetic crystal
is clean, why?? Tubes are not fast they make lousy square waves even when
fed them.? that and many of the radios have tuned circuits before the final and
the output is tuned.? OFten if you qsy across them band touching up the tuning
is required.? ?That is what selectivity and tuning does for us and too us.
Modern radios are wide band amps that will make efforts to reproduce what
they were fed.? So the basic solution is still, filters, lacking that, a very clean
source.? Alas the uBitx has a square wave source and no way to clean up
before the amp, a hole is there to fill.
Allison
|
Unfortunately, they went and outlawed spark in 1929.? ? ;-)
Jerry
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On Mon, Mar 4, 2019 at 11:28 AM, bill wright wrote:
use an old noise generator.? that is a very broadband signal
you can probably tailor it to the HF band
73 kd5yyk
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I use an old noise generator.? that is a very broadband signal you can probably tailor it to the HF band 73 kd5yyk
On Monday, March 4, 2019, 11:46:12 AM CST, Jim Sheldon <w0eb@...> wrote:
Not enough coffee this morning Jerry,? However, there is NO way to create a "pseudo sine wave" that will cover that frequency spread (1.8 to 30 MHz) with the current setup and Jerry's right, the only way is to use proper LPF filtering for all the bands. ?Unfortunately the 4 supplied are too broad to do the job properly and with only the supplied # of relays, it's not possible to switch extra ones in and out to achieve the desired results without some serious cut/paste modifications to even the V5 uBITX board.
Jim
------ Original Message ------
Sent: 3/4/2019 11:10:13 AM
Subject: Re: [BITX20] Pseudo-Sine?
You have that backwards.
CLK2 goes into the mixer at D1,D2, and is at the CW operating frequency.
CLK0 and CLK1 are dead in the water when transmitting CW.
Class C power amps are how most CW-only transmitters have worked over the last 100 years
Class C creates?a big honking square wave that then needs to be sorted out by effective low pass filters.
The solution for the uBitx is simple enough, make the transmit LPF's work properly.
Unfortunately, the relays are kind of tough for some of us to work on,
and few can be bothered to measure the results.
Jerry, KE7ER
On Mon, Mar 4, 2019 at 08:49 AM, Jim Sheldon wrote:
I don't believe that will work as CLK02 is not used for CW transmit. CLK01 produces "ON FREQUENCY OF TRANSMISSION RF (square waves) for CW
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I believe Allison has found that the four transmit LPF's are adequate.
It is the board routing imposed by using the minimum possible number of relays?
that is allowing those harmonics to sneak through.
Using more expensive relays designed for use at RF can also help.
Since this is primarily an SSB rig with CW as an afterthought, I don't think we can complain too much.
As I see it, the intent is to provide a minimum usable rig to encourage tinkerers to tinker and learn,
and in this it succeeds.? The tinkering required to move CW keying to the D3,D4 mixer should be
quite interesting and easy to do.?
If you want proper CW operation, your next project is clean electronic QSK.? ?;-)
Jerry, KE7ER
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On Mon, Mar 4, 2019 at 09:46 AM, Jim Sheldon wrote:
Unfortunately the 4 supplied are too broad to do the job properly and with only the supplied # of relays, it's not possible to switch extra ones in and out to achieve the desired results without some serious cut/paste modifications to even the V5 uBITX board.
?
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Most attempts at transmitting CW on *Bitx* variants over the last 15 years have involved?
injecting an audio tone into the mike input.
Ideally, the result is indeed exactly the same as any other CW transmission.
This forum goes back to 2004, lots of examples of injecting an audio tone for CW right here.
But unbalancing a mixer should give better results.
Either unbalance mixer D1,D2 with CLK2=TransmitFreq? and CLK1=CLK0=dead as on the stock uBitx,
or unbalance mixer D3,D4 with CLK2=VFO,? CLK1=45mhz, CLK0=dead as I just proposed.
Better results because:
? ? No close in crap due to distortion in your audio oscillator, mike amp, or modulator
? ? No opposite sideband due to a not quite perfect crystal filter
? ? No residual carrier due to a not quite balanced modulator and a not quite perfect crystal filter.
? ? It's much simpler to implement
The first three issues are unavoidable for SSB transmissions given this architecture.
But easily avoided when transmitting CW, by way of shutting down the modulator (CLK0=dead) and unbalancing a mixer.
On the other hand, this is primarily a QRP SSB rig.
Less than ideal CW operation may be acceptable for some if not using an external power amp.
Have at it as you see fit.
Jerry, KE7ER
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On Mon, Mar 4, 2019 at 10:18 AM, Evan Hand wrote:
When I tested the SSB harmonic performance with a single audio tone, it looked to me like a CW carrier. I also noted that the harmonics were much lower using the full SSB path.? Is a simple solution to create a pure audio tone that is keyed with the PTT signal line?? The built in side tone generator would need to be significantly filtered to make it into a clean sine wave.
Just an idea, not really into CW myself (at least at this point).
73
Evan
AC9TU
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When I tested the SSB harmonic performance with a single audio tone, it looked to me like a CW carrier. I also noted that the harmonics were much lower using the full SSB path.? Is a simple solution to create a pure audio tone that is keyed with the PTT signal line?? The built in side tone generator would need to be significantly filtered to make it into a clean sine wave.
Just an idea, not really into CW myself (at least at this point).
73
Evan
AC9TU
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Ignore that last paragraph of my previous post, included below.
It's garbage text.
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On Mon, Mar 4, 2019 at 10:14 AM, Jerry Gaffke wrote:
We're assuming there is no 12mhz energy present at the D3,D4 mixer (CLK0 is shut down).
And that the D3,D4 mixer is unbalanced using the CW-KEY scheme currently found at D1,D2.
Oh, and that D3,D4 attenuate CLK1 by 6dB (I'm not sure what happens when the mixer is used like that).
A CLK1 of -13dBm should get you into the ballpark,?
Jerry?
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Ted
bill wright