Date   
Re: Erratic tuning with my new uBitx

Chris Clarke G3SQU
 

Hi Ian
Just to let you know that my straight key behaviour has now improved out of sight with v1.061, which is fantastic. I was finding that different keys behaved differently and could be unreliable, my favourite Speedex in particular, so I'm really pleased about that.

Also my receiver is now performing far better for CW operation than with v1.01: I had been wondering if there was a problem that the SSB passband was being used for CW, as when I was tuning to zero-beat at 600Hz, where my passive audio filter peaks, the signal would not just be getting weaker but there was so little of it left I could barely hear it! The only benefit of using my filter was that I didn't hear so much QRM either. Now this doesn't happen, I'm gad to say so it's improved my operating experience immeasurably. I took part in the SP-DX competition at the weekend without being able to use my audio filter and was just swamped by all the competing stations. I did manage 34 QSOs, but again I was struck that those powerful signals, that were so strong when 2-3 KHz off tune, were barely audible once I'd tuned them to my 600Hz offset/RIT - the band was so busy there was always QRM from 2-3 KHz off frequency. Not being an SSB operator, nor having ever owned a good SSB-capable rig, I had never come across this particular 'feature' ... seems obvious now!

However, it has left me with another question! I am using CWL because it 'feels' better: I tune above the signal carrier and my RIT offset is subtracted and so my signal has the same frequency as the signal I have tuned in, but as it is below my listening frequency I feel that I am operating with the USB and therefore it should be called CWU! Is my logic faulty or have I got my rig configured all wrong?

Hope you are not pulling your hair out with my naive questions pre-digital age questions ... I'm not sure if I dare start asking about the BFO configuration!

Despite the queries I am having a fascinating and very rewarding time with this rig and your enhanced software, and I am extremely grateful that you have put in so much time and effort.


Best 73 Chris
G3SQU

PS I don't have a microphone so I'm basically staying away from all SSB-related issues if I can!

Re: POP fix

ve7hcw@...
 

Thanks to Don ND6T and Gary AG5TX on the insight of why there is a feed back thump on receive when the condenser mike is bumped. I have added an extra resistor and a 2n7002 MOSFET  to clean up the noise. using the KISS principle  to keep every thing simple as possible to procure  and using one value of resistors , capacitor and transistors . I have posted in the file section.

Re: AGC circuit to try?

ajparent1/KB1GMX
 

On Tue, Apr 10, 2018 at 11:29 am, Jerry Gaffke wrote:
do think your gain control scheme using the 1n400x parts would work fine.
Though one BAP64Q gives more dynamic range, and can be all in one spot.
They are better at higher frequencies.  However at lower HF it may be problematic.
The 1N4007 is fairly slow and makes a terrible rectifier at 10KHz, I tried them years
ago for a LVSMPS to go from 24V down to 5V.  Schottky was a must.

And is just plain cool.
It's puzzling to me that they can maintain a 50 ohm impedance so well.
There are several designs that as the diode goes to high resistance its complement
is going to low resistance into a resistor.  With care this works well to the Ghz and
higher range.  Check page 9 of the attached PDF.

I'll put the Microsemi hand book in the files area.

Allison

Re: POP fix

Rick Price
 

Tried to open the new uploaded .sch file in Eagle. Message says start
missing. Is Eagle the correct program to open this in or was another program
used. Thanks

Rick
KN4AIE

Re: Variation on Ian's KD8CEC uBitx software (based on his 1.04 release for now) and ATU sketch. #ubitx

John <passionfruit88@...>
 

Fine and useful research Jerry. Thanks.

73, John (VK2ETA)

Re: SI5351 simultaneous clock changes #ubitx-help

John <passionfruit88@...>
 

Hello Jerry,

Tried both methods and came back to your idea..hihi

The lookup table (four frequency points, plus interpolation) does the job better.

For info about the si5351 clock updates, the chip waits for the 8th register to be written to effect the frequency change.

I wrote a method to do as you said changing both clocks first 7 registers then quickly writing the 8th ones. It reduces the clicks but not 100%. Plus the FWD power reading gets messed up when the ATU tunes.

So now I have low, medium and high power dialled up in the menu. Neat.

Thanks for your help.

73, John (VK2ETA)

Re: #uBITX polyfuse? #ubitx

K9HZ <bill@...>
 

Depends what you are trying to protect... It's as good as a slo blow fuse.


Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

Owner - Operator
Big Signal Ranch – K9ZC
Staunton, Illinois

Owner – Operator
Villa Grand Piton – J68HZ
Soufriere, St. Lucia W.I.
Rent it: www.VillaGrandPiton.com
Like us on Facebook!

Moderator – North American QRO Group at Groups.IO.

email: @Doc_Bill

-----Original Message-----
From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Keith VE7GDH
Sent: Tuesday, April 10, 2018 3:28 PM
To: BITX20@groups.io
Subject: [BITX20] #uBITX polyfuse?

Anyone using polyfuses with a uBITX instead of a fuse? I have some here, but have never played with them before. Would they react quick enough to provide any real protection, or would they be just too slow?

--
73 Keith VE7GDH




---
This email has been checked for viruses by AVG.
http://www.avg.com

Re: #uBITX polyfuse? #ubitx

Doug W
 


If you access the list from https://groups.io/g/BITX20/topics there is a search function.  Here's the last discussion https://groups.io/g/BITX20/topic/7489182 regarding polyfuses and other things.

VK4PLN's Radrino replacement boards

K9HZ <bill@...>
 

Nick VK4PLN…  your Boards showed up today.  They look very good.  Now to build a couple up.  Thanks again!

 

 

Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

 

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

 

Owner – Operator

Villa Grand Piton – J68HZ

Soufriere, St. Lucia W.I.

Rent it: www.VillaGrandPiton.com

Like us on Facebook! facebook icon

 

Moderator – North American QRO Group at Groups.IO.

 

email:  bill@...

 

 


Virus-free. www.avg.com

Re: AGC circuit to try?

K9HZ <bill@...>
 

So back more years than I care to count, I designed and build my first receiver.  That is when I first learned how to build AGC circuits.  I did a lot of research…  At that time most of the leading edge designs based upon the latest published theory came out of places like Collins, RCA, Hammarlund, etc.  They all had certain things in common… A good RMS detector and voltage amplifier/ follower, a low pass filter, an integrator with variable time constant (variable AGC timing), and a DC offset amplifier (provides a place to put an RF Gain control).  My receiver was transistorized so I had to use what I had gleaned from the tube world in the transistor world.  I did a lot of experimentation, but the attenuating element I used in the end was something quite simple… a dual gate FET.  Everywhere from the first RF amp, through the IF and mixer-amps I used dual gate FETS.  It was quite simple to use the AGC voltage out of the DC offset amplifier (just an op amp) to (essentially) turn the gain up or down on those FETs.  I’ve replaced Q10 with a BF998 and rematched/ rebiased the part.  With just a variable voltage source on G2, it seems to work as you would expect (variable gain).  A little more gain but a little less noise too.  I’ll have to take this to my RF lab to see how the new front end is actually performing.

 

The difference here to the pin diodes is that you won’t have the IMD issue.

 

 

Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

 

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

 

Owner – Operator

Villa Grand Piton – J68HZ

Soufriere, St. Lucia W.I.

Rent it: www.VillaGrandPiton.com

Like us on Facebook! facebook icon

 

Moderator – North American QRO Group at Groups.IO.

 

email:  bill@...

 

 

 


Virus-free. www.avg.com

Re: AGC circuit to try?

Gordon Gibby <ggibby@...>
 

​fascinating.

Thanks!!


learned a lot.



From: BITX20@groups.io <BITX20@groups.io> on behalf of K9HZ <bill@...>
Sent: Tuesday, April 10, 2018 8:34:47 PM
To: BITX20@groups.io
Subject: Re: [BITX20] AGC circuit to try?
 

So back more years than I care to count, I designed and build my first receiver.  That is when I first learned how to build AGC circuits.  I did a lot of research…  At that time most of the leading edge designs based upon the latest published theory came out of places like Collins, RCA, Hammarlund, etc.  They all had certain things in common… A good RMS detector and voltage amplifier/ follower, a low pass filter, an integrator with variable time constant (variable AGC timing), and a DC offset amplifier (provides a place to put an RF Gain control).  My receiver was transistorized so I had to use what I had gleaned from the tube world in the transistor world.  I did a lot of experimentation, but the attenuating element I used in the end was something quite simple… a dual gate FET.  Everywhere from the first RF amp, through the IF and mixer-amps I used dual gate FETS.  It was quite simple to use the AGC voltage out of the DC offset amplifier (just an op amp) to (essentially) turn the gain up or down on those FETs.  I’ve replaced Q10 with a BF998 and rematched/ rebiased the part.  With just a variable voltage source on G2, it seems to work as you would expect (variable gain).  A little more gain but a little less noise too.  I’ll have to take this to my RF lab to see how the new front end is actually performing.

 

The difference here to the pin diodes is that you won’t have the IMD issue.

 

 

Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

 

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

 

Owner – Operator

Villa Grand Piton – J68HZ

Soufriere, St. Lucia W.I.

Rent it: www.VillaGrandPiton.com

Like us on Facebook! facebook icon

 

Moderator – North American QRO Group at Groups.IO.

 

email:  bill@...

 

 

 


Virus-free. www.avg.com

Power curve flattening...a lot more #ubitx

John <passionfruit88@...>
 

Got some pretty good results with limited memory usage to flatten the power curve, but only in voice/digital modes (SSB).

I use the first IF shift to produce a fixed attenuation to keep the output power within the required limits.

The process is two fold, a one off calibration exercise then I have a menu item that selects Low, High or Max power.

For mine I have used 5W and 10W as targets for the Low and High values.

I get the following results (I have modified the final stage with  RD16s plus other changes):

80m to 10M in Low power settings I have variations between 4 and 6 watts. In High setting I get a range between 9 and 11 watts.

I use only 16 bytes of data points (could be stored in EEPROM if desired).

In my ATU I use a spare digital output of the 2nd Arduino to send a 1500Hz tone, low-pass filtered, to the microphone input. The audio filtering plus the 2nd IF filter take care of the audio harmonics and the signal is clean. This could be done in the Raduino if digital lines are freed like with an I2C display.

That way I can tune in low power and more importantly I can transmit digital modes in low power without having to adjust the drive every time I change bands.

I will update the code in the file section so that it can be incorporated elsewhere if desired.

Thanks Jerry for the fixed table idea.

All the best,

73, John (VK2ETA)

Re: Power curve flattening...a lot more #ubitx

Jerry Gaffke
 

Very clever, and very cool!
Much of what you have figured out could be applied to other attenuation schemes.


On Tue, Apr 10, 2018 at 06:32 pm, John wrote:
Got some pretty good results with limited memory usage to flatten the power curve, but only in voice/digital modes (SSB).

Small audio amplifiers BC637

ohwenzelph
 

I want  to duplicate the small audio amplifiers at https://ludens.cl/Electron/audioamps/AudioAmps.html
but he uses a BC637 & BC640 pair. They have the BC640 at mouser but NOT the BC637. What should I use instead for the BC637?
Or do you know a reliable place to get real ones?
(Or is there another equivalent complimentary pair that would be ideal to use instead?)

thanks

jerry aa1of

Re: #uBITX polyfuse? #ubitx

lostfrogsrecords
 

Yep!

They work slowly, need a current limiting resistor to allow the polyfuse to reach cutoff temperature before the protected device fails.  Again, slow...

Ki4PSR

On 4/10/2018 6:29 PM, K9HZ wrote:
Depends what you are trying to protect... It's as good as a slo blow fuse.


Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

Owner - Operator
Big Signal Ranch – K9ZC
Staunton, Illinois

Owner – Operator
Villa Grand Piton – J68HZ
Soufriere, St. Lucia W.I.
Rent it: www.VillaGrandPiton.com
Like us on Facebook!

Moderator – North American QRO Group at Groups.IO.

email: @Doc_Bill


-----Original Message-----
From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Keith VE7GDH
Sent: Tuesday, April 10, 2018 3:28 PM
To: BITX20@groups.io
Subject: [BITX20] #uBITX polyfuse?

Anyone using polyfuses with a uBITX instead of a fuse? I have some here, but have never played with them before. Would they react quick enough to provide any real protection, or would they be just too slow?

--
73 Keith VE7GDH




---
This email has been checked for viruses by AVG.
http://www.avg.com





Re: Power curve flattening...a lot more #ubitx

John <passionfruit88@...>
 

Thank Jerry, but I am standing on the shoulder of giants.

Yes agree about the applications, and I like your idea of changing the mixer unbalancing from the first to the second IF stage to get the same benefit in CW. I might try that one day when I stop fiddling with other features..lol.

73, John (VK2ETA)

Re: VK4PLN's Radrino replacement boards

Nick VK4PP
 

Im glad you are happy with them, See my blog for a few photos, https://vk4pln.blogspot.com.au/
73 Nick

Re: #uBITX polyfuse? #ubitx

Jerry Gaffke
 

As a means of protecting the IRF510's, I think a polyswitch in the PA-PWR line should work great.
The IRF510's mostly fail due to overheating, a small polyswitch will have far less thermal mass
then the IRF510's plus heatsinks.

Often an LED and resistor in series are placed across the polyswitch,
such that when the polyswitch opens up the LED turns on.
That tells the operator to shut down power and let the polyswitch reset.

Would be interesting to experiment a bit, the IRF510's are cheap.
Turn up the gate bias pot till something gives.
My bets are on the polyswitch (rated for say 2 or 3A, will blow somewhat north of that).

I doubt you need a limiting resistor in this particular case. 

Jerry


On Tue, Apr 10, 2018 at 07:38 pm, lostfrogsrecords wrote:
They work slowly, need a current limiting resistor to allow the polyfuse to reach cutoff temperature before the protected device fails.  Again, slow...

#bitx40 #parts #bitx40 #parts

VE7WQ
 

Hi,
I'm selling due to my changed workload a recently arrived, unopened box of
BITX40 with Raduino for $59 +$10 shipping to US and Canada.
Estimated delivery time is 3-5 working days.
Offering it first here, before I put it up for sale on eBay.
Please send an e-mail, if interested.

Re: Small audio amplifiers BC637

Jerry Gaffke
 

The BC637 shares a datasheet with the BC639.
The BC639 seems to be exactly the same except for a slightly higher voltage rating, it is available.
So not a mystery that the BC637 would disappear.

Jerry


On Tue, Apr 10, 2018 at 07:33 pm, ohwenzelph wrote:
I want  to duplicate the small audio amplifiers at https://ludens.cl/Electron/audioamps/AudioAmps.html
but he uses a BC637 & BC640 pair. They have the BC640 at mouser but NOT the BC637. What should I use instead for the BC637?
Or do you know a reliable place to get real ones?
(Or is there another equivalent complimentary pair that would be ideal to use instead?)