I also uploaded the files to folder "W3JDR" in the files section.
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I thought I had saved a message that someone had some blank boards for the Raduino board.? Can not find it. Could whoever has those blank boards contact me off list at: rmowery28146@...de ku4pt
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Re: ND6T AGC implementation for uBIT-X
Nick,?
Relative to DX postage. I have shipped 1-2 small parts overseas in an envelope before but never 2 whole small kits and boards in one airmail envelope. The local Post Office wants a US Customs Form on all overseas mail containing what they can feel as parts and some DX Post Offices don't want anything that "can clog their automated equipment" ......so that means a padded envelope and higher rates.?
Even using the special "Non-Machineable Surcharge" stamps (which I am using for US shipments because of the included parts) is no guarantee that they won't be run through automated equipment, .....but it's much less than a "First Class small package"? ?
73 Kees K5BCQ
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PS to my previous:
I thought I attached the files, but I don't see any reference to them on my end. If there's a trick to this, can someone instruct me?
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If anyone is interested in reviewing and commenting, I have attached the schematic (2 pages) for my "Raduino Pill" board. This is a first draft;? Some pin assignments are TBD and there are undoubtedly errors. I'd like inputs on these. I'd also like suggestions about best usage of 'Pill' pins.
Some notes:
1) All connectors are the Dupont KF25xx types as already used in the uBITx.
2) I added some optional resistor networks to try to center the Pill's 3.3V logic levels to drive the standard 5V LCD supplied with the uBITx. This might not be necessary.
3) There are 2 I2C connectors and 2 SPI connectors. These share common busses.
4) There are on-board regulators for 5V and 3.3V. The 3.3V regulator drives the Pill's 3.3V line when the USB isn't connected (See my previous posting about this).
5) The Analog interface has optional scaling resistor networks. One of the inputs is configured with a capacitively coupled voltage divider. This is to sample received audio levels for the S-meter.
I wanted to get this out for peer review before I leave town for a few weeks. I'll finish the layout and order boards when I return. I will pick up emails while I'm away, so comments to keep me thinking are appreciated (please be gentle!)
Joe
W3JDR
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Re: boosting the power on 28 MHz
#ubitx
Just a thought, but maybe we are approaching this backwards.? It might
be easier and more appropriate for QRP use if we were to attenuate the
lower frequencies to match output at 30 MHz.?? 8-)
Arv
_._
On Thu, May 24, 2018 at 1:38 AM, WA9PWR <bill@...> wrote: Thanks for the help, Nick.? I think I will wait until Allison works out the flat power output problem.? 15 meters is my favorite band.
73, WA9PWR
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Re: RF power chain mods and improvements..
I haven't measure the filter bandpass.
But just listening to it, it sounded ok to my ears, even when going way down the skirt.
And as I recall, I had to crank it over more than 2k khz before it seemed to be attenuating noticeably.
Busy now, but will take another look at that today.
Do you have a datasheet for the filter being used that you can point me to?
Jerry
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Show quoted text
On Thu, May 24, 2018 at 07:41 am, Ashhar Farhan wrote:
Ian's software is a clever hack. It has ons drawback though, as it pushes the signal into 45 mhz filter's skirt, the signal will have sloping bandpass with more than 10db slope from one end to the other within the passband. Have I understood this correctly??
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Re: RF power chain mods and improvements..
What this means to me is that the rf chain is missing a stage... the driver to the PA. ?Ive thought this all along and planned to completely redesign the rf chain from scratch.?
?
Dr.?William J. Schmidt - K9HZ ?
On May 23, 2018, at 7:07 PM, Glenn < glennp@...> wrote:
Allison, what i am seeing in my 'proto' build of driver stages only, using MPSH10's, is a flat response within 1dB BUT that's with relatively low drive levels using the Rigol at -20dBm input. If I up the SA output level to around -2dBm (~150mVrms) which I think is the nominal level driving these stages, then the response is much worse.?? I also see severe +ve clipping levels at the base of the Q92 etc stage. Using the sig gen (HP8640B) to drive the driver stages with 150mV, I get around 500mW out at 7MHz, rapidly dropping as the frequency rises.? Clearly, as you have said, the stages just can't deliver enough power to the FET's over the whole range. Unfortunately I don't have any 2N3866's here but do have a few 2N4427's i could try. (500MHz Ft only though)? For the 2N2369 stage (Q90), I have the PH2369 which appears to be the same part. Does the clipping I am seeing in the final driver stage, mean that stage needs to be re-biased with the 2N3866's?? If so what did you use? Also, have you investigated what levels come out of the Modulator Vs frequency? It will also need to be relatively flat also for driver mods to work. glenn vk3pe On Wed, May 23, 2018 at 08:35 am, ajparent1/KB1GMX wrote:
Testing note..
How I arrive at the issue of gain vs frequency.
One was on paper using the well know EMRD feedback amp spreadsheet.
Every try said not possible unless the device has a FT of greater than 600mhz
THe simple test is we need a gain of 39 (~16db at 3mhz) and at 30mhz we need?
a device Ft of not less than 1170mhz based on the Ft/F rule of thumb.? We can
however get away with a bit less with only a small decrease in gain.
The other was a mod to the board and measure:
I removed the IRF510s and added a trans former to go from the gate connection
to 50ohms (1:1), added 10db 1W pad for safety (protect the Rigol). and to keep the?
mosfet out of the test.
Lifted C1 to isolate the TX amp from the LF and hooked a piece of coax with a.1uf cap at the and to
the input of Q90.??
RV1 set to 100% so we see total stage gain.
Enabled TX mode with out Raduino, jumper T/R to 12V..
Set up RIgol DSA 815Twith tracking generator for -20dbm output from 3 to 30 mhz.
I didn't do a screen capture though I should have.
( I used lower drive as I'd seen gain compression in driver and pre-driver at higher
output levels at higher frequencies. this is device HFE related at higher currents.
this makes the system look worse.)
The result was about 45DB gain at 3mhz falling to 34db at 30mhz. A drop of nearly 10db.
The slope of the curve was such that at about 7mhz we were already dropping by 2db.
Power out of the driver for that setup was .255 Watt at 3mhz falling to .023W at 30.
We could get more power by cranking up the trancking generator output at lower
frequencies but gain compression at higher power levels limited us at?14mhz and
above.
Adding emitter caps and inductors to the feedback helped but the result was still
well short.? The net effect is the curve was flatter to about 13mhz then resumed?
sloping down.
Why is this.? The 2n3904 has a FT of 300 (nominal) and the rule of? thumb is ft/f=Beta
BEta is the maximum attainable gain for the stage.? So at 3mhz the result is 100, lots
of gain and its tamped down with feedback to 39 (~16db).? ? At 30mhz the result is 10!
10 is 10DB of gain...? ?Paralleling transistors is supposed to help that but the result is
typically a 3db improvement at higher frequencies. So for 4 stages at approximately
16db per stage at 3mhz showed?48db (Not allowing for transformer losses) but close
to the result of 45 DB gain.? ?However at 3mhz we are supposed to get 30db and
did get 33 so we are doing better than predicted?but well down from 3mhz.
Adding the various caps and inductors in the feedback to the q90, pre-driver, driver made
the curve flatter but at 14mhz we are now 3db down and would end up at 35db down at?
30mhz.? Clearly the 2n3904s were not cutting it.? Its hard to get more than? a beta of 20
out of two in parallel and we need an effective beta of at least 39.
This is why higher frequency transistors that work at higher currents are being pursued.
Devices with FT greater than 650 mhz gets use within about 3-4db without circuit tricks.
3Db flatness means at 3mhz say 10W and 30mhz 5W.? Adding tapered feedback helps
some so we should see near 7-9W at 30 and so far my results confirm that using
2n2369 for Q90, and the pre-driver one 2n3866,? and driver two 2n3866.? ?All of those
have an Ft of 600mhz or so and power handling suitable for the stage they are in.
The problem is 2n3866 and 2n5109 are not cheap.
NOTE: if as was, we get about 4W (at 30mhz) from the IRF510s with the measured drive
it confirms the MOSFET is being starved!.
Putting the irf510s back in and grabbing the 50W 30db power attenuator agrees
nicely as the IRF510s at 3mhz were netting about 16db of gain and at 30mhz a
respectable 14db of gain.?
Conclusion is we need uniform gain and the ability to deliver more than .5W
(about .7 would provide good headroom).? ?The IRF510 has enough gain.
Now I wait for lower cost parts.
Allison
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Re: RF power chain mods and improvements..
This approach works well but you must first have enough gain at 30 MHz to use this technique.?
?
Dr.?William J. Schmidt - K9HZ ?
On May 24, 2018, at 7:24 AM, Jerry Gaffke via Groups.Io < jgaffke@...> wrote:
Allison,
Getting the analog stuff to where it is flat from 3.5-30mhz is preferred if the mods are easy,
we much appreciate your efforts in this in this regard.
However, gain per band can be done with zero additional hardware,
a rare case of being very very cheap:
? ??/g/BITX20/message/50217
? ??/g/BITX20/message/50184
The KD8CEC software already has this feature fully implemented.
I am curious if you have ruled this method out for some reason.
You'd think it might mangle the audio frequency response some,
but I can't hear anything other than reduced amplitude as I take it down the skirt.
That's a fairly broad filter.
Jerry, KE7ER
On Thu, May 24, 2018 at 05:25 am, ajparent1/KB1GMX wrote:
Gain per band has been widely used and work save for its rarely cheap and tends
to add a lot of circuitry.
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I am curious if it would be practical to make? a 2 meter ssb version of the BITX and how many would be interested in one?
Roxie -- K1AUS
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Re: RF power chain mods and improvements..
Ian's software is a clever hack. It has ons drawback though, as it pushes the signal into 45 mhz filter's skirt, the signal will have sloping bandpass with more than 10db slope from one end to the other within the passband. Have I understood this correctly??
On Thu, 24 May 2018, 19:44 Jerry Gaffke via Groups.Io, <jgaffke= [email protected]> wrote: I haven't messed with KD8CEC's software, or even looked at it yet.
Likely will use it when I try out digital modes.
I could provide stripped down uBitx software that implements the 45mhz attenuator on transmit
if that's of interest, would take less than a day.? Suggested interface:? Knob tunes operating frequency
during receive, knob tunes the 45mhz attenuator during transmit while holding the operating frequency constant.
Jerry?
On Thu, May 24, 2018 at 06:24 am, Jerry Gaffke wrote:
The KD8CEC software already has this feature fully implemented.
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Re: RF power chain mods and improvements..
I haven't messed with KD8CEC's software, or even looked at it yet.
Likely will use it when I try out digital modes.
I could provide stripped down uBitx software that implements the 45mhz attenuator on transmit
if that's of interest, would take less than a day.? Suggested interface:? Knob tunes operating frequency
during receive, knob tunes the 45mhz attenuator during transmit while holding the operating frequency constant.
Jerry?
toggle quoted message
Show quoted text
On Thu, May 24, 2018 at 06:24 am, Jerry Gaffke wrote:
The KD8CEC software already has this feature fully implemented.
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Re: RF power chain mods and improvements..
Based on the known data that if the gain falls with increasing frequency the fix is obvious.
Use devices that have better performance over the frequency range.??
The fix the problem approach is direct. We have an abundance of gain at lower
frequencies and a 10-13db drop in gain over frequency.? The cause is easy to find
as the 2n3904 with a FT of 300 is producing about 1/2 to 1/3rd the gain at 10m as
at 80m.??The RV1 100% power is under 4W at 10m in my unit while easily hitting
13w (saturation, clipping, splatter) at 80M.? If we had sustain enough gain to get
10W at 10M most of?this would not be an issue.
How to fix that:
One is to not use a device that runs out of gain around 7-10 mhz.? The current path
I'm? following is that finding a better choices of devices and possibly at low cost.
To that end I found BFR106 a nice 5ghz ft device, that I even have on hand
and would be good in the Q90 spot.??Infineon still makes them and they are
about 29 cents @ quantity 10 for SMT.
The alternate path is take a one off approach and use devices known to work but
are not cheap or easily had world wide.? For example replace Q90 with a MIMIC
such as ERA-3 (minicircuits) which is good to high uhf.? Then go with one of
the?wideband devices usually found in CATV amps such as mrf586, 2sc1252,
oth the old favorite 2n5109.? Likely a mix would be right depending n power
needed at that stage.? This would be the high priced way to go and it may
be very difficult for others to copy due to availability and board level mods.
In both cases adding a bit of equalization (tailor the feedback and emitter bypasses)
can improve the performance.??
Allison
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toroid on USB line for CAT control
#ubitx
Ever since I have been using cat control for FT8 on the CEC firmware. I have been having intermittent lockups involving the usb port. I have a work around it seems that I must have been getting some rf back into the computer.?
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Re: RF power chain mods and improvements..
Allison,
Getting the analog stuff to where it is flat from 3.5-30mhz is preferred if the mods are easy,
we much appreciate your efforts in this in this regard.
However, gain per band can be done with zero additional hardware,
a rare case of being very very cheap:
? ??/g/BITX20/message/50217
? ??/g/BITX20/message/50184
The KD8CEC software already has this feature fully implemented.
I am curious if you have ruled this method out for some reason.
You'd think it might mangle the audio frequency response some,
but I can't hear anything other than reduced amplitude as I take it down the skirt.
That's a fairly broad filter.
Jerry, KE7ER
On Thu, May 24, 2018 at 05:25 am, ajparent1/KB1GMX wrote:
Gain per band has been widely used and work save for its rarely cheap and tends
to add a lot of circuitry.
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Re: spurious signals on FT8
#ubitx
A few things I found with my Bitx40 and Ubitx. Turn the drive down in the rig itself for digi modes, also check for any kind of ground looping. When I was 1st running my Bitx40 I ran r136 at half of what is normal after getting reports I was txing in a few spots at once. This was also in combination with a ground loop from my pc, after moving r136 it was reduced and again after using a laptop it was completely gone. I found the audio was over driving the radio even set very low and caused a lot of issues.
?Another thing to make sure is a DC blocking cap on the mic line so as not to mess with the computer or the interface if you use one.
73
--
David
?N8DAH
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Jack,
? Thanks for that info, I will have to try that. I am still debating the analog style vs. the bar graph. I think analog looks nice if done right and I am going to give it my best effort but if all fails I might just use a real analog meter instead. I am really enjoying the challenges and trying to find solutions.
Stephanus, K6NG
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On Thu, May 24, 2018 at 02:07 am, Tom, wb6b wrote:
Call me old fashioned, but shouldn't the radio transmit on the displayed frequency and any frequency offset to create the tone for CW be done as a receive frequency shift, such as RIT? Maybe the preference has changed.
You are absolutely right. We had similar discussions for the Raduino sketch for?BitX40 at the time. During TX the frequency shouldn't be shifted - the actual TX frequency should be?equal to?the frequency as shown on the display. During RX, the frequency needs to be shifted to the same amount as the side tone frequency setting. 73 Allard PE1NWL
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Initially, I had an analog S-meter on the JackAl board, but changed to a bar meter, mainly because I was running out of nano-acres. You can make the meter look "less jerky" if, when you compare the new position with the old position, you divide that difference by some constant (e.g., 5) and do the erase-redraw in 5 steps rather than in one jump. Sometimes it will look better if you throw in a small delay (e.g., perhaps 20-30 ms) between each redraw, too. That way, the needle "slides" to the new position rather than jump to it.
Jack, W8TEE
On Thursday, May 24, 2018, 8:15:20 AM EDT, stephanus1@... <stephanus1@...> wrote:
I have also started to play with my 3.5 inch display and so far i am good with the results. The only part I am not sure about is how to do the serial coms from the raduino to the display. The attaced video is a work in progress.
More info is always appreciated.?
Stephanus
K6NG?
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Re: RF power chain mods and improvements..
HI Rahul,
Gain per band has been widely used and work save for its rarely cheap and tends
to add a lot of circuitry.
Equalizers are well known too.? For the astute may notice I'm taking that path.
To do that you need enough gain across the bandwidth and a way to tamp it down
so its flat.? You can't do that with 3904s as they lack the gain at 30mhz.? Fix that
and feedback with contouring can then work.? ?As is we have a default negative
contour as the over all gain diminishes with frequency due to transistors used
in the transmitter stages.? ?Fix that and the performance improves greatly.
The trick if any is KISS, keeping it simple and supportable.
Allison
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K9HZ
_Dave_ AD0B
N8DAH
Allard PE1NWL