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Re: kit-projects AGC with uBITX v5 - need help #v5

Rob French (KC4UPR)
 

Black to ground, resistance, below.  To be clear, this is measuring from the square pad at the end of the diode, where I have the thin black wire soldered in the picture.

OFF (down) - 0 ohms
SLOW (middle) - ~800 ohms
FAST (up) - ~800 ohms

So clearly something is not right here.  I'm guessing that SLOW should resolve to 1M and FAST should be something less (470k?), but not 800 ohms! 

I also went and individually measured the two resistors.

The 470k resistor... I am able to measure a good value across that in OFF and SLOW. When I measure it in FAST, it shows as a short.  I don't think that makes sense.

The 1M resistor... All switches positions, it measures as 0 ohms.

Unless there is other broken component providing a path to ground, my guess is that something is broken in my switch. I do know that I had removed a washer or nut from the base of the switch in order to have it mount flat against the inside of my rig.  I wonder if I overtightened the mounting nut and caused some type of mechanical failure or deformation inside the switch.

I'll need to verify, but it should be an easy matter to desolder those connections and put some jumpers in to test the settings. 

What's the part # on that switch?  I'll probably need to order a couple.  Or, alternatively I could make up some little relay circuit board to put the AGC under software control...

Regards,
-Rob KC4UPR


Re: kit-projects AGC with uBITX v5 - need help #v5

KE2GKB
 

No worries rob life gets us all eventually, So off hand I'm not 100% sure what could be going on. So a few tests to try.

Can you try a 1V RMS ~550HZ signal? Sometimes I have noticed the detector is a little odd on higher frequencies. Second, Could you measure the resistance presented on the black Switch wire to ground in all 3 positions?

A low S-Meter (Or bias voltage as it also happens to be) is either the input buffer transistor being bad, Or what its feeding being bad. At least those are the typical issues. Lets start there

-- Tim Keller - KE2GKB https://shop.kit-projects.com


Re: kit-projects AGC with uBITX v5 - need help #v5

Rob French (KC4UPR)
 

Sorry,  you had asked about the black wires by RF Gain. Those are two lengths of RG174 to a front panel RF gain pot. I have since removed those and replaced with a jumper while I troubleshoot.


Re: kit-projects AGC with uBITX v5 - need help #v5

Rob French (KC4UPR)
 

Sorry for the delay on this.  Life.

The black wire corresponds to the purple/magenta wire in the instruction manual, i.e. it connects across the two middle terminals of the switch.  The switch is kind of buried at the moment, but if needed I can try to dig it out.  I will note that with the the switch in the OFF position, my S-meter display goes away (as expected), and it reappears (albeit not very good) in either SLOW or FAST.  I'm fairly confident that I do have the switch wired up correctly.

I've tried injected a 1V RMS 1500 Hz audio signal into the yellow audio line.  I was hoping to see that result in AGC action being force, but no luck.  That caused little-to-no change in the value of my S-meter/the corresponding ADC (I will note in general that the ADC input voltage I'm seeing never gets above about 0.3-0.5V).  (As an aside, I also heard the 1500 Hz signal through my headphones... I'm not entirely sure how it's getting into the audio chain???)

Final note, if you look in the photo I posted before, right above the two RG-174 lines that go to the RF gain control, there are two solder pads with nothing between them.  Looking at the manual for the AGC, it appears there is supposed to be a capacitor here.  This appears to be an addition relative to the original ND6T design, but I imagine maybe it could have been an intentional change to the kit?  What was this capacitor for, what's it's value, and could its absence be the cause of any of my issues?

Thanks,
Rob KC4UPR


Re: Easy Bitx Kit #bitx20 #bitx40

Bob Lunsford
 

Very interesting, Sunil. I'll take a keen look at the 40M version. Thanks for the information.

Bob — KK5R

On Sunday, November 22, 2020, 9:57:10 AM EST, Sunil Lakhani <vu3sua@...> wrote:


It's been few months we launched are Easy Bitx Kit .
The kit has some new features that eleminate the earlier drawbacks of bitx kits .
The manual with complete details can be found on our website .
Easy Bitx has fifteen individual packets which help building in step by step.Just like the old days .
The kit is also available on our website .
The kit can be build for any one band .
80mt 40mt or 20mt .
The website has 20mt kit by default .if you wish a 40mt kit then include a note in purchase .
80mt one we will start soon .
Those who want the kit without enclosure can email us vu3sua@...

https://amateurradiokits.in

Best of 73s 
Sunil 


Re: uBitX v.6 schematic / driver and finals transistor symbols / #ubitxv6 #v6

Bob Lunsford
 

Most Romance languages (languages derived/descended from Latin) are that way. Personal pronouns, for example, are used with family and friends and considered impolite and improper if used with someone who is not family/friend. Portuguese is also in that category as is French. All pronouns in those languages use specific verb forms as well for nearly all pronouns and where the same form is used for more than one pronoun, it is considered useful to the student of that language but learning them as would a child would render them faulty or awkward usage if the wrong verb form were used with a particular pronoun. It would be like saying "I are" or "you is" in English. It's just not done unless Ebonics is used, which the former head of the Dept of Education in CA once said his mother told him was "bad English."

Even knowing Portuguese, those who do not know Spanish or Italian can usually get the gist of what is said. It's not as close as an English speaker attempting to read some Irish or Scottish brogue.

Imagine that there are over 350 languages and dialects in India, More than 450 languages and dialects in China and I once read that there were 1380 languages and dialects in Philippines but some of them only had 3 or 4 people speaking them. Once those people died, the language also died. But those in the Philippines came mostly from six Malasian roots.

Foreign language interests me as I grew up with Portuguese and Spanish and when in High School and college in Brazil, I had to study Latin and French... I since then have dabbled in Italian and Japanese.

This also adds to the interest in the V6 since it is useful to listen in to many shortwave broadcasts. It's nice to have an alternative to CW, sometimes.

Bob — KK5R

On Sunday, November 22, 2020, 9:08:20 AM EST, Todd Carney <carneytf@...> wrote:


The difference between "formal" pronouns and "familiar" ones is an ordinary feature of many languages: Italian is one of many including Spanish and French. Most school children in the English-speaking world are at least exposed to it.

On Sun, Nov 22, 2020, 1:08 AM IW4AJR Loris <lorisbollina@...> wrote:
Hello Todd

It is extremely difficult to translate Italian into English ...
Italian is a complex and unique language in concepts and definitions, English is too simplistic a language to express certain concepts ... 
Do you want an example: 

tu sei -> you are 
voi siete -> you are 
tu hai -> you have 
voi avete -> you have 

it is enough for you ? .... Loris


Re: uBitX v.6 schematic / driver and finals transistor symbols / #ubitxv6 #v6

Bob Lunsford
 

Evan, I trust your interpretation of the data sheets. Your logic for opting for the IRF510 corresponds to my rationale for selecting this instead of the more expensive one. The operating voltage difference would indicate to me at first blush that the 510 may well get you by an SWR faux pas and anything that can keep me from removing the board to replace/repair broken final transistors is a decision maker.

Thanks again for the spec sheet details.

I had an SB-104 once that I built and a lightning strike down the killed the PA drivers because unless the radio is "on" the antenna is fed directly by the drivers which corresponds to Low Power operation. I did not have the direct replacement on hand but had transistors that were identical physically but were designed for UHF operation. I plugged them in and the radio worked perfectly since the UHF transistors were overkill as far as electrical specifications was concerned. This taught that such overkill is cheap insurance, in the long run. From then on, by the was, when the radio was not being used, it was switched to short out the output/antenna connector, another form of cheap insurance.

Bob — KK5R

On Sunday, November 22, 2020, 7:54:20 AM EST, Evan Hand <elhandjr@...> wrote:


Bob,
The IRF510 and RD15HVF1 can both be used in this design, but are not really electrically equal, nor are they near the same cost (if you can find the RD15HVF1 part).  For this transmitter, the RD15HVF1 would be a better part to keep the output more consistent across the bands.  

The IRF510 was designed as a high-speed high power switch.  The RD15HVF1 was designed to be used as a VHF power amp. 
The IRF510 has a higher voltage capability.
The RD15HVF1 has better gain at higher frequencies.

The BIG difference is in the price.  Doing a quick search on the internet gave an eBay price of $6.00 for the RD15HVF1 vs a Mouser price for the IRF510 of $0.98 for quantity one.

Since there are other parts of the uBITX that limit the power output at 10meters, the advantage of the higher frequency of the RD15HVF1 is negated to a large extent.  You could spend the $12+ shipping to experiment, but not really worth it to me.  It will not solve any of the earlier boards (v3, v4) purity issues so you are spending money for, at best,  a few watts at the higher end of the range.  You can get some of the frequency advantages by increasing the voltage to the finals in the uBITX with the IRF510s, the design for the RD15HVF1 is 12.5volts.  The side effect of increasing the voltage using the IRF510s is that the power goes up across all of the bands, not just the higher ones (for some this is a good thing).

Above are my interpretations of the datasheets I found and could be in error.  I just wanted to point out that they are not truly the same, just that both will work in the uBITX as designed.
As always I am happy to get any feedback or corrections so that I can continue to learn about this hobby.
73
Evan
AC9TU


Re: Email still coming in no email button selected

Vince Vielhaber
 

Could you be subscribed with more than on email address? Stopping one but getting the mail from another one?

Vince - K8ZW.

On 11/22/2020 12:11 PM, jaytee1@cogeco.ca wrote:
Admins....any suggestions.
I blocked this group on email and its still coming through. Now I am
really confused. Endstate, I may have to unsubscribe and only subscribe
when I have a question the un-subscribe....Not efficient at all.....lol


Re: uBitX v.6 schematic / driver and finals transistor symbols / #ubitxv6 #v6

Jerry Gaffke
 

Kind of painful here with our internet connection (come on Starlink!),
but did manage to grab the 5mB article from the arrl website for a look.
OCT 2010 - QST (PG. 37)  Homebrew Challenge II Co-Winner -- The Lowest Cost Entry;  
Author: Cripe, David, NM0S;   
http://p1k.arrl.org/pubs_archive/137696      (for ARRL members)

>  I doubt it's a linear amp, and thus not suitable for SSB.   
It's class E using EER for SSB transmissions, so definitely not a linear amp.
This Envelope Elimination and Restoration thing is very cool, I've considered trying it.
But I'm not aware of a commercial amateur product that uses it, and there are reasons for that.
Check for IMD!

>  I doubt it has flat gain from 2 to 30mhz like the QSX amp.
Strictly 40m

>  I doubt it gets 50W when running on 12vdc.
Actually, he is running those IRF520's on 12v.  Which is rather surprising to me.

>  It probably needs a signal source with way more power than the QSX amp,
>  as the QSX amp includes a suitable driver stage.
Article doesn't say, but I'd guess it wants a watt or two.  So maybe 10x the QSX amp.

Jerry


On Sun, Nov 22, 2020 at 11:55 AM, Jack, W8TEE wrote:
Thanks!
 


Re: uBitX v.6 schematic / driver and finals transistor symbols / #ubitxv6 #v6

Jack, W8TEE
 

Jerry:

Thanks!

Jack, W8TEE

On Sunday, November 22, 2020, 12:40:29 PM EST, Jerry Gaffke via groups.io <jgaffke@...> wrote:


Jack,

The IRF520 has double the gate charge, so needs more drive.
It is not trivial to build a good wideband driver, and more power can mean an extra stage.
If all you want is 10W in a linear amp, two IRF510's is a good choice.

I'll have to look at that QST article.
I doubt it's a linear amp, and thus not suitable for SSB.
I doubt it has flat gain from 2 to 30mhz like the QSX amp.
I doubt it gets 50W when running on 12vdc.
It probably needs a signal source with way more power than the QSX amp,
as the QSX amp includes a suitable driver stage.

Hans also has a 50W kit for a class C amp (non linear) at $29.50:
    https://www.qrp-labs.com/50wpa.html
Includes a PIN diode TR switch, which is very cool.
Uses two IRF510's.

Jerry, KE7ER



On Sun, Nov 22, 2020 at 09:13 AM, Jack, W8TEE wrote:
I was just reading an article by David Cripe (QST, Oct., 2010) which won the QST Challenge that year. He designed a 50W amp based in the IRF520. His amp cost $32 to build and the power transistors are dirt cheap. Is there a reason why they are not more widely used?
 
Jack, W8TEE

--
Jack, W8TEE


Re: SWR meter with second arduino

Gerard
 

Dennis,
Otherwise, I spent my afternoon watching videos on Kicad.
Well, I learned more. I hope to progress. LOL
cdt


Re: SWR meter with second arduino

Gerard
 

Dennis,

I only make hardware changes that exist. I have no control over the Arduino software at all. It’s a bit of a pile of things known to avoid having a spagetti type PCB  with all these additions.
If you manage to drive the equalizer with the 2nd arduino as a graphic menu, it would be interesting.
Watch this video
http://hamradiodesigns.com/index.php/ubitx-jackal/
this will give you ideas

cdt


Re: SWR meter with second arduino

Dennis C (WC8C)
 

On Fri, Nov 20, 2020 at 10:17 AM, Gerard wrote:
I was looking at this documentation for my information and I have a doubt about the connection.
http://www.hamskey.com/2019/04/installing-swr-and-rf-power-sensor-in.html
The wiring diagram looks incorrect to me.  I put the forward/reverse power to the second Arduino.  I seem to recall seeing an updated wiring diagram at one point, but I cant find it now.  The way the Hamskey site is organized is unfortunate - it makes it difficult to find the most up-to-date information.
 
--
Dennis WC8C


New PCB available for WA2EBY linear amp #linear-amp

Ken K0KV
 

After running my uBITX barefoot for the past 18 months (with 1700 FT8/FT4 contacts) I decided it was time to add a little more power.  The ever-popular WA2EBY linear amp seemed like a good route, except that nobody offered the circuit board anymore.  On a whim, I sent an email to amateurradiokits.in to see if they had even one board left over.  Sunil, VU3SUA responded that the old boards were gone, but they were just a few weeks away from releasing a totally new board for this design.   I asked to be their first customer, and very shortly had the new board in hand.  Here's my review (unsolicited, uncompensated): 

Having seen pictures of the earlier board in past construction articles, I can safely say the new board is a big improvement.   Cosmetically, it has all the professional elements that were previously missing: plated-thru holes and vias, solder masking and comprehensive silk-screening.   The size is a few tenths of an inch longer and narrower than the original, which turns out to be an excellent match for an inexpensive 150 x 60 x 25mm heatsink that is widely available on EBay as of this writing. 

Before you start building, you need to make two design choices.  First, your input attenuation – pads and traces are provided for a standard pi-network attenuator, but it’s up to you to choose the amount of attenuation needed for your setup and then compute the appropriate size/wattage resistors. Plenty of websites can help with these calculations.  Likewise, space is provided for a single band low-pass output filter, but the L and C values are up to you.  Again, no problem –  go to any WA2EBY article/website/blog published in the past 11 years and you’ll find them listed.


A few notes related to the photo:
  •  yes, there are still surface-mount capacitors – 10 of them.  And yes, mounting them seemed scary at first, but turned out to be much easier than I thought.  Plenty of YouTube videos are available to walk you through that process.     
  • the IRF510 pins need to be bent up 2-3 mm to allow the MOSFETS to mount flush to the heat sink while still maintaining adequate spacing for the board itself.  
  • the board has mounting holes for SMA connectors at the RF input and output.  I don’t generally use SMA’s on my projects, and the holes didn’t match up with the ones in my junk box, so I just soldered some mini-coax directly to the pads.
  • two other connection pads allow you to route the input signal to an external attenuator and back, if desired.  Otherwise, these points (J4 and J5) need to be jumpered. 
Because this is a mature design, you’ll find a wealth of published articles available to provide detailed advice on everything from component selection to toroid winding to expected performance.  It’s like having multiple assembly manuals to choose from.  Construction went smoothly, and the amp worked perfectly the first time I applied power.   As always with this design, tune-up consists of simply setting the bias current on the IRF510’s.   Stability is excellent, and very little drive is required to obtain full power out.  At some point I’ll do more comprehensive testing, but for now I’m having too much fun operating with it.
 

As a final note, the original QST articles (Mar, Apr 1999) provide an excellent analysis of the thermal challenges that come with running a pair of IRF510’s at 40+ watts.  Based on this, I've decided to run my amp at 30 watts output for the time being, until I have time to construct a better cooling system.  A couple of dB output power just seemed like a small price to pay to spend my time operating instead of replacing IRF510’s.

The WA2EBY PC Board can be ordered from amateurradiokits.in.  It is currently available as a bare board only, but will eventually be sold as a semi-kit as well.  Until it’s added to their website, you can email an inquiry to the address shown on their Contacts page, they’ll respond with the details.     


Re: SWR meter with second arduino

Dennis C (WC8C)
 

With all this, I think what I did will be a better base for the second Arduino code as Dr. Lee's version has very little available memory left.  You could also look at some thing more powerful that an Arduino to give you more room for additions.  If you do this, I suggest something with at least 2 uarts so you can eliminate the need for software serial.
--
Dennis WC8C


Re: uBitX v.6 schematic / driver and finals transistor symbols / #ubitxv6 #v6

Jerry Gaffke
 

Jack,

The IRF520 has double the gate charge, so needs more drive.
It is not trivial to build a good wideband driver, and more power can mean an extra stage.
If all you want is 10W in a linear amp, two IRF510's is a good choice.

I'll have to look at that QST article.
I doubt it's a linear amp, and thus not suitable for SSB.
I doubt it has flat gain from 2 to 30mhz like the QSX amp.
I doubt it gets 50W when running on 12vdc.
It probably needs a signal source with way more power than the QSX amp,
as the QSX amp includes a suitable driver stage.

Hans also has a 50W kit for a class C amp (non linear) at $29.50:
    https://www.qrp-labs.com/50wpa.html
Includes a PIN diode TR switch, which is very cool.
Uses two IRF510's.

Jerry, KE7ER



On Sun, Nov 22, 2020 at 09:13 AM, Jack, W8TEE wrote:
I was just reading an article by David Cripe (QST, Oct., 2010) which won the QST Challenge that year. He designed a 50W amp based in the IRF520. His amp cost $32 to build and the power transistors are dirt cheap. Is there a reason why they are not more widely used?
 
Jack, W8TEE


Re: Email still coming in no email button selected

Reed N
 

Stab in the dark: is it possible that you signed up twice with different emails, and you're getting the emails forwarded by your client, rather than directly to the account?


Reed


Re: S-Meter Nextion, ask

Dennis C (WC8C)
 

I have not use a LM358 so I cant say what the advantages are.  I just Used what I had on-hand.  A quick peek at the data sheet and it seems like it should work as a replacement.  I think the key feature you want is that the op amp output can swing to ground.

With the circuit you linked, there is rectification/smoothing in the Op Amp output.  I think this should should work for the SMeter, but I think the FFT/CW Decode features will not work properly as it expects the full signal (preferably centered at 2.5V)

Other than that, be sure that the signal into the Arduino doesn't exceed 5 volts.

If you get the LM358 to work, please let me know so I can update the page with the alternative.
--
Dennis WC8C


Re: uBitX v.6 schematic / driver and finals transistor symbols / #ubitxv6 #v6

Mick
 

I’ve been wondering about swapping the 510 with 2 520’s. I’m not going to do it I have a nice little 70w amp ( it uses irf540’s) But in these swap discussions I’ve not seen the irf520 option brought up.
--
 

73
Mick VA3EPM 


Re: SWR meter with second arduino

Gerard
 

Dennis,
Here’s what I’m thinking about.
First of all, I made a Ubitx house from A to Z and I only use the reception part for now. See my different posts.
I want to improve what exists, and for that I read everything that was written on the HFsignal website.
What I would like to add (list not completed)
A separate power supply for the Nextions(s) (Bridge,self and regulator separately)
Internal box regulation (fan trip)
Installation of a removable SSB filter (Small plug-in pcb). This to change the frequency easily.
Taking into account changes seen on power stage (2n2222 + modified transformers)
Establishment of a AGC
Setting up an equalizer
Setting up preconnexions for HF power amplifier (relays?)
Encoder changes (Added resistances to suppress noise)
Added components for SWR meter (Your circuit or KD8CEC (lm358))
Addition 2nd arduino
Addition of additional control transistors on free legs of the 2nd Arduino for future controls (ex of relays)
Addition 2nd Nextion
All these modifications exist, they must be implemented on a circuit.
I’m not a Kicad specialist, I spend a little time at night on it. It took me 4 days to make a small circuit. That’s unfortunate, because you actually have to do all the operations by hand.
I thought that after I made the schematic and the choice of prints, that he was going to generate a circuit. A priori no, there too it is manual...unless I do not master the tool. Connexions must be do manually!! (Only "Cheveulu" to help.
it's just a project.

NB: I also just saw that we can also put another Arduino. The V3 should work I think. Attention, on A.... o, we sell V3, but it looks like a Nano. The cabling is not the same. I think the programs should work on the V3.

So some work this winter....
cdt

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