That is nice, and so simple, I think I could do that one too, Vince. I'm wondering if a person could change the transformers to 10uf caps like the duinovox has. I may need to try it just for fun. The duinovox will stay in my rig. It is working really well with 10 watts. I imagine, if a person were smart, they could find some uses for those extra pins and memory on the second nano in the radio.??
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Well, I just got my Bitx40 Raduino....Let me build and test that out and I'll get to the uBitx. I want to mate them with a 25W PA I plan to design. Why? Because I want to try to make a broadband PA w/o needing LPFs...
--
AncelB, MIT EE6002
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Re: W8TEE Software Release 1.07-09
Yep. The cost is $8, domestic shipping is included. Use PayPal to econjack@.... Be sure to add your shipping address.
Jack, W8TEE
From: "robert.m.cox@..." <robert.m.cox@...>
To: [email protected]
Sent: Thursday, October 5, 2017 1:14 PM
Subject: Re: [BITX20] W8TEE Software Release 1.07-09
Is it still possible to purchase the TFT/VFO boards for this project??
73,
-Rob
N4MN
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No, Pat. RC is still at FET gate, just FET drain via C to Q1 base. Value of C could alter the severity of the FET's effect, but would still not have much effect on overall action. If connecting C to Q2 or Q3 base likewise, though I'd be cautious of messing up Zout of Xtal filter. I'd be trying around 100pF there, same as the coupling cap.
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Jerry et al: Q1 should be fine, to 'normalise' the chain. 'messing up impedances' will only occur once the FET becomes resistive, i'e. Vg > (turn-on threshold), at which point all that happens is reduced throughput, the original intent - self-normalising. I'd keep it pre-demod - Z there really matters! And strong signals will always cause havoc. If AF detection, they'd need to be reasonably close to tuned-f to do much damage.
PIN diode schemes evidently work best, but this would be far simpler and thus less expensive, plus easier to understand and still with tolerable performance.
73 , Dex
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Here's the thread on distortion: ?? /g/BITX20/message/32043
You need to detect the signal level somewhere after the crystal filter,? since you only want the signal you are receiving to engage the agc action. Top of the volume control pot is probably good enough. Most solutions posted to this forum attenuate after the audio pre-amp at Q16. But as Henning points out in that thread, Q16 is limiting our dynamic range. So the AGC circuit should attenuate the signal before Q16.? Exactly where you should attenuate isn't terribly clear to me. If attenuating at Q1, the noise level when strong signals are present could be louder than it needs to be. Messing with Q1, Q2 and/or Q3 will affect impedances there, which may impact the performance of the BPF, ring mixer, crystal filter, and maybe even the demodulator. I'd probably just use a pin diode attenuator at the output of Q3 as noted in the above thread. Jerry
On Thu, Oct 5, 2017 at 03:47 pm, Dexter N Muir wrote:
For anyone using this scheme: I recall someone encountering distortion due to something in the Rx before this point. I had the thought (that still remains): why not 'feed-forward' like AM AGC? My replacement Raduino is currently en route, and I haven't yet had the chance to try this - has anyone else done so? I envisage detecting the audio level at the top of the Vol pot as this does, but taking the FET drain to Q1 base via 0.1uF and with time constants in between adjustable for fast/slow "hang". What say, folks?
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I have it apart now working on a new case so I can't verify it. ?It's not 5 secs though. ?It's more like 1.5-2 secs and I guess that is due to the interaction of the threshold, ?% of charge, and RC. ?It is a pretty smooth gradual increase back to full volume.
?Is your idea to move the RC circuit to the base of 2n2222?
Pat Griffin
http://www.cahabatechnology.com/aa4pg.html
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BTW, Pat - 100uF, 47k? T=CR - mics x megs = seconds, 100 * .047 = 4.7s. Is there a threshold? or do you have around 5 seconds of gradually-increasing signal?
73, Dex
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Further thought, Pat: FET might not turn on till about .5(Vpeak) ... threshold :) ?
73, Dex
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BTW, Pat - 100uF, 47k? T=CR - mics x megs = seconds, 100 * .047 = 4.7s. Is there a threshold? or do you have around 5 seconds of gradually-increasing signal?
73, Dex
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Pat, it's all said - think about it. 'Normalises' signals through the whole Rx chain once respectable level achieved, leaving it running at full gain until then. Transients knock it back till 'hang' fades out. Same as AM. Just concept, untried ...
73, Dex ZL2DEX
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I haven't gotten around to it but I was thinking of changing the hang time by adjusting the 100k and 47uf cap on the 2n7000 gate. ?The hang is about right with a 100mf instead of 47mf but that is just what I happened to have. ?Say some more about your idea
of doing it at the 2n2222 base.
Pat
Pat Griffin, CPA, PhD
http://www.cahabatechnology.com
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For anyone using this scheme: I recall someone encountering distortion due to something in the Rx before this point. I had the thought (that still remains): why not 'feed-forward' like AM AGC? My replacement Raduino is currently en route, and I haven't
yet had the chance to try this - has anyone else done so? I envisage detecting the audio level at the top of the Vol pot as this does, but taking the FET drain to Q1 base via 0.1uF and with time constants in between adjustable for fast/slow "hang". What say,
folks?
73 de ZL2DEX
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For anyone using this scheme: I recall someone encountering distortion due to something in the Rx before this point. I had the thought (that still remains): why not 'feed-forward' like AM AGC? My replacement Raduino is currently en route, and I haven't yet had the chance to try this - has anyone else done so? I envisage detecting the audio level at the top of the Vol pot as this does, but taking the FET drain to Q1 base via 0.1uF and with time constants in between adjustable for fast/slow "hang". What say, folks?
73 de ZL2DEX
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Ok, so it also has a resistor and a couple of caps. Anyway, here it is:
While wsjtx doesn't put a steady tone on the opposite channel from the data, it does put out data in both channels. That data is more than enough to turn the fet on and transmit. Until the other day, I was only putting out a bit over a watt into a long wire with an unun. I still managed to make several contacts with this circuit as an interface.
Vince.
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On 10/05/2017 08:18 AM, Vince Vielhaber wrote:
Rather than the duinovox I found a simpler circuit for interfacing data.
It consists of 3 small audio transformers (got 10 for a little over $1, a
couple of 1N4148 diodes and a 2n7000. I won a cheap ($4) USB sound card
on ebay so I built it all onto a circuit board and put a mic connector on
it to just plug into the Bitx. Next to the sound card, the mic connector
was the most expensive part.
I'll post a link to the schematic later today when I get home, unless I
can find it again sooner.
Vince.
There was quite a bit of interest in this over in the FB group, so thought
I would consolidate and add here. The project is call the "duinovox" by
KB9RLW. I built this very simple, low cost circuit and added in the bitx
enclosure. The wiring for the pots and interface jacks are hanging loose
just to see if it would work before drilling more holes. Also a picture is
attached of my very first CQ? on 7.074, at 2 watts, and two stations
replying. Serial 719 is getting a workout. If you do this, take
precautions with the final irf510 because of the heat generated by the
long transmissions.
--
Michigan VHF Corp.
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Amplified Microphone and the BITX40
I have an old Telex ProCom I amplified microphone that has never been used and I was thinking that it might be a good match for my BITX40.? It uses an Electret element and has a fixed level output amplifier.?? Runs off an N type battery.?? Anyone have an opinion as to whether I will overload and possibly damage the mic input circuit on the BITX ?if I used this?? Will I need a blocking capacitor since it does not require DC from the BITX?
Thanks,?? Jim?? W6yxy
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Brent,
I am using that circuit and it works pretty well. ?See my posting #32796. ?I changed a couple of caps and tapped it at the diode and fed that to an s-meter (or vu meter) circuit which displays on line 3 of?a 4x20 lcd. ?Yes, the connection is at the volume
control.
73,
Pat AA4PG
Pat Griffin
http://www.cahabatechnology.com/aa4pg.html
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Hello
I'm thinking of trying to build an age circuit. I have ample room on the board I used to build the anti thump circuit. Does anyone have an opinion as to what is the best circuit to use? I was thinking of the VU2ESE configuration. Where is that circuit inserted
into the bitx? At the volume control?
Thanks for all the help and advice.
73
Brent VE3CUS
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Hello
I'm thinking of trying to build an age circuit. I have ample room on the board I used to build the anti thump circuit. Does anyone have an opinion as to what is the best circuit to use? I was thinking of the VU2ESE configuration. Where is that circuit inserted into the bitx? At the volume control?
Thanks for all the help and advice.
73
Brent VE3CUS
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Hello All,
Let me introduce me a little. (sorry if I'm writing faults in English, no so easy using a French corrector !)
I'm 49 years old . Electronic engineer in radiocommunication and power conversion. Amateur radio since 1990.
I'm buiding a lot of my equipmenst, last big project was a high level 2m SSB transceiver. I did a 80 m CW transceiver working from 3V to 6V (1W to 4 W).
I plan to build an kind of ubitx using the Raduino (thanks to Farhan's work !).
The difficuly will be to supply the transceiver with a 5 V USB power pack !
Of course transmit power will be limited to 1 W (linear) to 2 W at compression (the output stage of the MOSEF PA is allready working !)
Now I'm facing to the diver of the PA..no easy to ensure flat response at low voltage.
To developp at 50 Ohms is more easy to qualify each sub-circuit : simulating, testing, assembling...
I confirm the fact of using a 45 MHz Xtal filter to avoid looping back (I had this problem on a HP 8590 spectrum close to an internal IF )
It is important to load mixers at 50 Ohms on each port, or dissipate unwated products in a waste load.
LPF front of 1st mixer is very important to avoid image of FM broadcast band if you hare close to big transmitter (that's my case)!
I will continue this project as soon as I will have time ...not in stress !
Best 73 F5RCT Jmat ( ..shorter than Jean-Matthieu !)
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Re: W8TEE Software Release 1.07-09
Is it still possible to purchase the TFT/VFO boards for this project??
73,
-Rob
N4MN
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Randell,?
Running up on the increased inverse complexity of convenience, time to start monitoring power rails? Not being off the shelf plug ins, can¡¯t just add up published specs. You are having way too much fun.
I am going to use this lesson in our builders group, next month.
Craig KM4YEC
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On Oct 4, 2017, at 11:45 PM, RCC WB5YYM < curtis03@...> wrote:
Added another accessory board to the rig. Built up the duinovox by KB9RLW. It works great for FT8 even with the bodged wiring for testing. The VOX is cheap and easy to build.?
<front duinovox.jpg>
and the board plugged into the rig
<20171003_215226.jpg>
The 4 boards visible are regulated power, relay board, VU2ESE AGC, and duinovox designed by KB9RLW. I'm now out of slots...but could build an expansion board pretty easily if needed.?
I do have an intermittent low power output problem. It started after another mod done and then undone. I haven't checked much, but I am not overly concerned about it? since the amp doesn't like much more than 1 watt drive anyway. It does have me curious, and at some point, I will give it some attention.?
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Searching for the word "error" in your listing shows that it's having trouble with the si570 library.
Could be a difference between Farhan's version of the library (he coded that several years ago) and what's currently available.
You can either dig back into the repository and find the correct (older) version of the si570 library
or you can figure out what those calls are doing and adjust the sweeperino code to work with the currently available library.
The latter might be best, you get any bug fixes and you have reason to learn about the si570 calls.
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On Thu, Oct 5, 2017 at 04:49 am, Rob Bleumer wrote:
But at compiling it goes wrong, which library¡¯s should I use, and where can I find the necessary version. I got the next failure messages:
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Ancel
Brent Seres/ VE3CUS
Jean-Matthieu F5RCT
Rob Cox (N4MN)
Craig Thibodeaux