Re: AGC Circuit for uBITX Featured in July 2019 QST Magazine
Since the entire circuit set is 12V or less, your 16V caps should work just fine. ? ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Rob French (KC4UPR)
Sent: Monday, August 12, 2019 12:40 AM
To: [email protected]
Subject: Re: [BITX20] AGC Circuit for uBITX Featured in July 2019 QST Magazine ? Thanks.? Any thoughts on voltage rating for the capacitors, especially the "big" electrolytic ones?? (10uF, 100uF, 470uF... I'm assuming they're electrolytics.)? I looked at the Hycas schematic, and that calls out 50v for all the caps, but I don't have many of those... got lots of 16v though! -- ¡_. _._
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Re: AGC Circuit for uBITX Featured in July 2019 QST Magazine
Thanks.? Any thoughts on voltage rating for the capacitors, especially the "big" electrolytic ones?? (10uF, 100uF, 470uF... I'm assuming they're electrolytics.)? I looked at the Hycas schematic, and that calls out 50v for all the caps, but I don't have many of those... got lots of 16v though!
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Re: AGC Circuit for uBITX Featured in July 2019 QST Magazine
As I recall, the JackAl AGC circuit is just the Hycas AGC circuit lifted from QST December 2007.? Al added a couple of things like a switch to turn it off.? The FETs are nothing special.? A 201 and a 102 will work fine. ? ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Rob French (KC4UPR)
Sent: Sunday, August 11, 2019 10:57 PM
To: [email protected]
Subject: Re: [BITX20] AGC Circuit for uBITX Featured in July 2019 QST Magazine ? I'm looking at possibly lifting just the AGC circuit out of the JackAl design, and seeing if I can stock it out of my junk box.? But... the only JFET's I have are MPF102, J201, 2N5486, and 2N4393... will any of those work?? Other than the MPF102, the rest were all originally purchased for audio work, so I can totally imagine them not being suitable.
Thanks!
-Rob -- ¡_. _._
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Re: uBitx and QCX review in QST August 2019
I agree: the video was nice, but lacking. Many very basic facts were left out. Seemed to be aimed at hams who already knew about the uBitx and just wanted to see one.
-- Donald, KB5PWL
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Re: AGC Circuit for uBITX Featured in July 2019 QST Magazine
I'm looking at possibly lifting just the AGC circuit out of the JackAl design, and seeing if I can stock it out of my junk box.? But... the only JFET's I have are MPF102, J201, 2N5486, and 2N4393... will any of those work?? Other than the MPF102, the rest were all originally purchased for audio work, so I can totally imagine them not being suitable.
Thanks!
-Rob
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For transmitting CW, clk2 drives mixer d1/d2 at the transmit frequency.? The modulator, 2 crystal filters, and 2 IF amps are not used.?
When transmitting SSB, all of that stuff must work.
Jerry, KE7ER
On Sun, Aug 11, 2019 at 08:56 AM, Evan Hand wrote:
Dan's suggestion on CW as a test is the correct course.? It will verify if you have an RF or Audio issue.
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Re: uBitx and QCX review in QST August 2019
Asher,
You may wish to contact ARRL and ask permission to host a PDF of the review article on your own website.? I'm not sure what the arrangement is for that sort of thing, but I've encountered that several times.? For instance, Elecraft has PDFs of the various ARRL review articles of their equipment for free download on their site.
73,
-- Dave, N8SBE
-------- Original Message --------
Subject: Re: [BITX20] uBitx and QCX review in QST August 2019
From: "Matthew Pitts via "
< daywalker_blade_2004@...>
Date: Sun, August 11, 2019 1:41 pm
To: [email protected]
There are a lot of videos related to the uBitX on YouTube that can add details that are missing in the ARRL video. Matthew N8OHU On August 11, 2019 11:26:38 AM EDT, Robert McClements < gm4cid@...> wrote: ?Ken Hansen, yes, agreed,? the QST article does make these points.
The video will be seen by many who do not have access to QST and who are
not familiar with the uBitx and they will get??information about the product.
that is a very incomplete and potentially open to misinterpretation.
As I stated earlier, ARRL could have done much better, disappointing.
Bob GM4CID -- Sent from my Android device with K-9 Mail. Please excuse my brevity.
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Re: VK4PP uBitx add-on Boards. (VK4PLN)
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Thanks Dan!
I appreciate the response.
I did lookup the mic wiring - that is where I started. ? Uniden BC-645 is a Cobra compatible electret 4 pin mic wiring 1-GND, 2-MIC, 3-PTT, 4-RX - I have 1, 2 and 3 wired correctly, I believe, per my enclosure instructions.??
Sadly - no 3.5mm plug at hand at the moment - but I will wire up the mic and PTT button that came with the kit and test.
Curious if anyone has experience with this mic.
Dean
KK4DAS
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Re: VK4PP uBitx add-on Boards. (VK4PLN)
Hi Everyone.
I have almost made it through the backlog of projects, so I should be able to start working on add-on boards again soon.
Cheers,
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Sorry. ?Think there is voltage only when the ppt is keyed for the uBitx?
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On Aug 11, 2019, at 5:55 PM, Dean Souleles < dsouleles@...> wrote: Thanks guys!
1. CW test produces power out! So far so good.
2. The mic I am using is a replacement electret mic:
3. I have it wired to the 4 Pin connector that came with the case, per the attached diagram
? ? Pin 1 - GND
? ? Pin 2 - MIC
? ? Pin 3 - PTT
Question - should there/will there be voltage from MIC to GND any time the radio is on?
I can wire up the mic that came with the rig to the 3.5 mm plug and give it a try also.
Thank you again,
Dean
KK4DAs
<38462384_10156437004964280_6827556150053961728_n.jpg>
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Wire the mike that came with the rig and use the plug to the phono mike input. ?Haven¡¯t looked at the audio diagrams recently but think the dc voltage should show up on the mike line when it is keyed by the ppt. ? Not sure about your wiring instructions that came with the chassis box. ? You should be able to measure a dc voltage on the mike line. ?? Also get on the internet and look up the connect wiring for your specific Mike. ?
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On Aug 11, 2019, at 5:55 PM, Dean Souleles < dsouleles@...> wrote: Thanks guys!
1. CW test produces power out! So far so good.
2. The mic I am using is a replacement electret mic:
3. I have it wired to the 4 Pin connector that came with the case, per the attached diagram
? ? Pin 1 - GND
? ? Pin 2 - MIC
? ? Pin 3 - PTT
Question - should there/will there be voltage from MIC to GND any time the radio is on?
I can wire up the mic that came with the rig to the 3.5 mm plug and give it a try also.
Thank you again,
Dean
KK4DAs
<38462384_10156437004964280_6827556150053961728_n.jpg>
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Step by step....
I have +5 volts on 4 pin connector pin 3 when the radio has power - it measures +5 against either Pin 1 or Pin 2 or the case.
Again - from the Uniden/Cobra wiring that I have found on the net it should be?
1. Gnd
2. Mic
3. PTT
Is there supposed to be voltage on the PTT line or am I possibly cross wired?
(as an aside - I really dislike mic wiring!)
And there was no 3.5mm pig-tail or connector in my kit - I presume I need a stereo plug - I can harvest an old PC speaker wire. ?? Just need to get that wiring right!
Dean
KK4DAS
Dean?
KK4DAS
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Thanks guys!
1. CW test produces power out! So far so good.
2. The mic I am using is a replacement electret mic:
3. I have it wired to the 4 Pin connector that came with the case, per the attached diagram
? ? Pin 1 - GND
? ? Pin 2 - MIC
? ? Pin 3 - PTT
Question - should there/will there be voltage from MIC to GND any time the radio is on?
I can wire up the mic that came with the rig to the 3.5 mm plug and give it a try also.
Thank you again,
Dean
KK4DAs
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If your mike is similar to the kit supplied one ?you will likely need a dc voltage to the mike for it to work. ?That should already be in the current design. ?Check the mike connectors for a dc voltage on the radio mike connector and make sure it matches with the equivalent mike cable pin. Otherwise you might not have audio from the mike.?
Next if you have a way to do it check for audio at the mike amplifier output on the radio board. ? ? Just trace through the circuit schematic. ?
Dan W3BU?
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On Aug 11, 2019, at 11:25 AM, Dean Souleles < dsouleles@...> wrote: Thanks Dan -
I will give CW try. I have a watt meter on the antenna output so that is how I know there is no RF out.
The mic is a cobra/uniden electret CB mic.? I believe the element is essentially identical to the element that came with the kit. ?
Dean
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Re: uBitx and QCX review in QST August 2019
There are a lot of videos related to the uBitX on YouTube that can add details that are missing in the ARRL video.
Matthew N8OHU
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On August 11, 2019 11:26:38 AM EDT, Robert McClements <gm4cid@...> wrote:
?Ken Hansen, yes, agreed,? the QST article does make these points.
The video will be seen by many who do not have access to QST and who are
not familiar with the uBitx and they will get??information about the product.
that is a very incomplete and potentially open to misinterpretation.
As I stated earlier, ARRL could have done much better, disappointing.
Bob GM4CID
--
Sent from my Android device with K-9 Mail. Please excuse my brevity.
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Re: uBitx and QCX review in QST August 2019
ARRL isn't a marketing firm, and I believe the video is kept behind a paywall for subscribers only.
Again, you can't buy the uBitx without going to HF Signals, who makes it very clear what is included and what the user must supply.
The video the ARRL produced meets the needs of the ARRL - I've never seen any of their 'in depth' videos get used as marketing collateral by any manufacturer, that's not what they are made for. If someone chooses to repurpose it outside the ARRL it is on that person to overcome any shortcomings the video may have in its new role.
My $0.02 worth, Ken, N2VIP
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On Aug 11, 2019, at 11:26 AM, Robert McClements < gm4cid@...> wrote: ?Ken Hansen, yes, agreed,? the QST article does make these points.
The video will be seen by many who do not have access to QST and who are
not familiar with the uBitx and they will get??information about the product.
that is a very incomplete and potentially open to misinterpretation.
As I stated earlier, ARRL could have done much better, disappointing.
Bob GM4CID
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Dean,
I assume that you were whistling or saying "Helloooooo" into the mic when measuring.? My v4 and v5 uBitx both do not register power out until audio is applied.
If you were able to calibrate with the stock firmware, it went into transmit mode for the calibration.? Did that register on the watt meter?
Dan's suggestion on CW as a test is the correct course.? It will verify if you have an RF or Audio issue.
If the CW checks out, then you wight want to wire up the supplied mic and button to the supplied 3.5 mm plug and try it.? I am pretty sure that the case kit that you got has both the 4 pin and 3.5 mm connections for the mic/PTT.
73
Evan
AC9TU
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Re: Want to increase audio gain in Q70 stage of Ubitx - ideas?
After a short discussion on EMRFD regarding the "minimalist DC receiver" (which uses the same gain stage design) resulting in a detailed explanation from W7ZOI (see there if interested), and previously more experimentation on my bench around different devices and bias settings, I've realized that I cannot solve the problem in the single NPN stage as originally envisioned.
As an alternative approach, I am taking the output of the AGC driver from the TDA2822 (U1-3 that ends up delivering output across R72), then coupling that signal into the audio gain pot which in turn drives U1-7. This provides a surplus of gain in this path (it puts the two stages of the TDA2822 in cascade) so that the audio gain control is now useful and can easily drive the output section of TDA2822 into clipping on no-signal noise (my original goal).
Some further work will be needed to ensure that the AGC detector (D10 etc.) does not adversely influence the audio at that point.
Dave
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Re: uBitx and QCX review in QST August 2019
?Ken Hansen, yes, agreed,? the QST article does make these points.
The video will be seen by many who do not have access to QST and who are
not familiar with the uBitx and they will get??information about the product.
that is a very incomplete and potentially open to misinterpretation.
As I stated earlier, ARRL could have done much better, disappointing.
Bob GM4CID
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MadRadioModder
Darrel H K0CXF
Nick VK4PP
