Date   
Re: Transmitter Mods

Satish Chandorkar
 

How you propose to control the drive to be of 5 watts on all bands for your 70 W amplifier
As the uBITX is giving much more power out put on lower bands  than on the higher bands

Satish

Virus-free. www.avast.com

On Fri, Apr 20, 2018 at 5:07 AM, Howard Fidel <sonic1@...> wrote:
Actually, I would prefer to rewind the transformer with a center tap, and eliminate the chokes, feeding the DC to the center tap.
Z for L8, L9 should be >> then the output impedance which looks like the antenna impedance for the 1:1 transformer.
I am adding a 70 watt amplifier to my uBitx, so I just need 5 watts out on all bands to drive it. I doubt I will do much more, on the transmitter, but I will have to see how the amp behaves. I may to to better equalize the output level between the bands.

Howard




On 4/19/2018 2:37 PM, Jerry Gaffke via Groups.Io wrote:
The parallel resonance helps us to a point, though an ideal inductor would generally be better.
For example, if the inductor is self resonant at 14mhz, we'd see much more power out on 20m
than we see on 10m.  I'd prefer to keep gain vs freq somewhat controlled and predicatable.

The caps are easier to add, easier to obtain, have a higher self resonance:
    https://electronics.stackexchange.com/questions/193608/self-resonance-frequency-for-mlcc-capacitor
Maybe add 220pF caps across all six of the 22 ohm emitter resistors, and forget the inductor?
Then add a variable cap somewhere around Q90 that can be tweaked to give the flattest response,
that setting may vary given your particular 2n3904 transistor characteristics. 
 
But the inductor in series with the negative feedback is a good idea.
If this can all be done with just 3 extra components and get good enough results across
the different uBitx's out there, I'm fine with that.

One other issue:
As Henning notes in post 45035, the chokes L8 and L9 are best wound on a single core:
See the discussion below figure 4 on this webpage, where he discusses how the bifiliar
approach works, though he does not discuss the individual choke solution:
    http://ludens.cl/Electron/mosfetamps/amps.html
I was seeing significantly worse results in how the uBitx final worked compared
to the WA2EBY final in my LTSpice simulation, could be due to these chokes.
    https://groups.io/g/BITX20/topic/9615903
I may have to play with that further, not obvious to me how or if the individual chokes
at L8, L9 would impact the results..

Jerry, KE7ER


On Thu, Apr 19, 2018 at 11:00 am, Jerry Gaffke wrote:
Good question.
It's a parallel resonance:  
    https://www.everythingrf.com/community/what-is-self-resonant-frequency



Re: receiver overload

Michael Shreeve
 

Just reading this initial post again. I was confused by it because its so different from my experience. I might have different conditions though. My antenna is balance and is a loop. A full loop on 80 meters. For transmitting I have a tuner,  but with or without it, and with different feed methds, such as coax, 450 open line, and 4 to one baluns, I've had excellent results with this tuner. I am in a low noise area. But, your problems seem to all be related to high signal levels, and possibly high noise levels . If that is what your antenna is receiving, I've had lower noise with my full waive 265 foot loop than any other type of antenna. It an amazing way to go. Of course, a dipole would be a much less efficient version of my antenna, and could display the lower noise attributes. Its definitely the way to go. 

--
Michael Shreeve N6GRG

Re: Transmit indicator light.

MAX <max@...>
 

Hi Gary.

 

I’ve been kind of busy and just got around to checking out this link.  It didn’t lead me to anything useful. 

 

Regards.

 

Max K 4 O D S.

 

I've Never Lost the Wonder.

 

Antique Electronics Site: http://www.angelfire.com/electronic/funwithtubes/

 

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Gary Anderson
Sent: Thursday, April 19, 2018 6:03 AM
To: BITX20@groups.io
Subject: Re: [BITX20] Transmit indicator light.

 

Hi Max,
I'm assuming that you have an enclosure from Sunil (VU3SUA) by the description.  He has pictures on his website showing how he has done the  RX/TX LED wire-up.
The website is  https://amateurradiokits.in/
the pictures are the second and third from the last.

He is picking up the 12V RX and TX control signals from the uBITX RX/TX relay by soldering wires to the bottom of the uBITX PCB.  He also picks up the ground from the relay.  He then routes 3 wires (RX,TX,GND) to a small prototype board with series current limiting resistors on RX and TX.  No reason you couldn't put your resistors anywhere along that route.  I would have put them right on the PCB.

Regards,
Gary
AG5TX

Re: receiver overload

John Sharpe
 

Hi Jacob,

Yes, I have done the RF gain mod and it works well - but still the tuner still makes a big difference.

John VK2VOL

On 20 Apr 2018, at 12:05 pm, Jacob Farnes via Groups.Io <kk6jtl@...> wrote:

The Bitx40 is my favorite radio to listen with once I did the RF gain mod via the two pin holes and cut the trace on the underside.

https://groups.io/g/BITX20/message/26490

I shouldn't have tombstoned the 10-ohm surface mount resistor. Just needed 2 wires and a potentiometer to be a variable resistor. Nice and quiet most days.

Re: receiver overload

Tim Gorman
 

I am using his new AGC circuit. It works well. You still get a slight
pop when an extremely strong signal first comes on but it is very short
and, to me at least, not annoying at all. You may want to lower the
1Mohm resistor to something smaller to decrease the pop, i.e. decrease
the attack time. The next time I open the case I'm going to try 500K.

tim ab0wr

On Thu, 19 Apr 2018 19:16:04 -0700
"Michael Shreeve" <@N6GRG> wrote:

I'm going to try ND6Ts new AGC version. He seems to think its the way
to go. Its here. My MOSFET's are on the way.
http://www.nd6t.com/uBITX/AGC.htm

On Thu, Apr 19, 2018 at 7:05 PM, Jacob Farnes via Groups.Io <
kk6jtl=yahoo.com@groups.io> wrote:

The Bitx40 is my favorite radio to listen with once I did the RF
gain mod via the two pin holes and cut the trace on the underside.

https://groups.io/g/BITX20/message/26490

I shouldn't have tombstoned the 10-ohm surface mount resistor. Just
needed 2 wires and a potentiometer to be a variable resistor. Nice
and quiet most days.


Re: for sale

n2tmc@...
 

What's the problem with the performance?

Re: receiver overload

Jim Sheldon
 

It's sure worth the effort to build & install it.  Made an S9++ signal into one that didn't hurt the ears and an S2 signal was readable at the same setting of the volume control.  Thanks ND6T for a very workable AGC circuit!

Jim, W0EB



Jim, W0EB

On Apr 19, 2018, at 9:16 PM, Michael Shreeve <shreevester@...> wrote:

I'm going to try ND6Ts new AGC version. He seems to think its the way to go. Its here. My MOSFET's are on the way. http://www.nd6t.com/uBITX/AGC.htm

On Thu, Apr 19, 2018 at 7:05 PM, Jacob Farnes via Groups.Io <kk6jtl@...> wrote:
The Bitx40 is my favorite radio to listen with once I did the RF gain mod via the two pin holes and cut the trace on the underside.

https://groups.io/g/BITX20/message/26490

I shouldn't have tombstoned the 10-ohm surface mount resistor. Just needed 2 wires and a potentiometer to be a variable resistor. Nice and quiet most days.




--
Michael Shreeve N6GRG

Re: anybody tried softrock and hdsdr with Ubitx?

Paul Schumacher
 

thanks Bill,
Paul


On Thursday, April 19, 2018, 6:46:47 PM CDT, K9HZ <bill@...> wrote:


Yeah Ian did… and he has a video on Youtube using it…

 

 

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@...

 

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Paul Schumacher via Groups.Io
Sent: Thursday, April 19, 2018 11:50 AM
To: BITX20@groups.io
Subject: Re: [BITX20] anybody tried softrock and hdsdr with Ubitx?

 

Has anyone tried a softrock and hdsdr with Ubitx to get the spectrum and

waterfall display?  (or something similar?)

 

If so, can you please describe how to go about doing it?

 

thanks,


Paul K0ZYV

Re: receiver overload

Michael Shreeve
 

I'm going to try ND6Ts new AGC version. He seems to think its the way to go. Its here. My MOSFET's are on the way. http://www.nd6t.com/uBITX/AGC.htm

On Thu, Apr 19, 2018 at 7:05 PM, Jacob Farnes via Groups.Io <kk6jtl@...> wrote:
The Bitx40 is my favorite radio to listen with once I did the RF gain mod via the two pin holes and cut the trace on the underside.

https://groups.io/g/BITX20/message/26490

I shouldn't have tombstoned the 10-ohm surface mount resistor. Just needed 2 wires and a potentiometer to be a variable resistor. Nice and quiet most days.




--
Michael Shreeve N6GRG

Re: receiver overload

Jacob Farnes
 

The Bitx40 is my favorite radio to listen with once I did the RF gain mod via the two pin holes and cut the trace on the underside.

https://groups.io/g/BITX20/message/26490

I shouldn't have tombstoned the 10-ohm surface mount resistor. Just needed 2 wires and a potentiometer to be a variable resistor. Nice and quiet most days.

Re: show your mic

Jerry Gaffke
 

You need to take a cigar, coat it with epoxy and a bit of fiberglass, 
use that for your mike barrel.

Jerry


On Thu, Apr 19, 2018 at 05:34 pm, <tony.vasile@...> wrote:
AAAAAAND here's the pic!
 
Tony KB9A 

Re: UbitX I2C GPIO Breakouts?

Tim Gorman
 

I've been using I2C from the w0eb radi2cino to the lcd for a couple of
weeks. I'm not seeing any kind of slow response.

If I read right it takes about 100us to do an analogRead(). On a
100kbps I2C bus it would take about 80Us for 8bits or 160us for a two
byte word. Not a big difference in speed, at least for reading data.

tim ab0wr

On Thu, 19 Apr 2018 16:44:22 -0700
"NNicholas via Groups.Io" <NNicholas=aol.com@groups.io> wrote:

I have used these chips on many projects and used them to drive led
displays, but for this application,  given the slower response of the
I2C serial bus, I would stick with the given direct I/O driven LCD
display and use the I2C serial to communicate with a second arduino,
to add more functions. That way you keep speed, have true
multitasking going on, and not only double the io, but you double
memory. I plan to add an custom auto antenna tuner to mine, and a 100
watt amplifier , all in the same enclosure. I will be using a second
arduino based processor to control both the filtering and switching
of the amplifier in and out, and seek and search for best antenna
match without having to interrupt the radio operations. That way,
when auto tune is turned on, the amp will drop out to low power , the
antenna will tune, and then return to the original settings. Like
wise as the radio is turned to various bands, the pi filters in the
amp can automatically switch with the band. Nick N8GIR

receiver overload

John Sharpe
 

Hi all,

I just had a thought about new users of the uBitx and the Bitx40.

I have both of these fine rigs but with my good antenna - a ZS6BKW at 30 feet - the receivers are swamped by noise and big signals on 40 metres.

When I tested just now a 59+ 10 signal on my IC-7300 was unreadable on the Bitexes with the big antenna (which has a low SWR at 40 metres) because of noise. With an antenna of just 6 feet of wire in the shack the signal was readable (but weak) on the Bitexes!

I usually use a tuner beween the antenna and the Bitexes - that works fine to tame the noise. Also I have fitted an RF control to the Bitx40 that helps quieten big signals.

But if you have lots of noise in the receiver and no tuner - try a smaller antenna on receive (it will be no good for transmitting).
If that improves things maybe you need a tuner or an RF control.

73s John V2VOL

Re: Extension cables for display/Raduino

Jonathan
 

Also see this article:  https://groups.io/g/BITX20/topic/7573243
It includes a link to a nice article (PDF) by Al Duncan VE3RRD showing how to make an extension cable from an old computer IDE cable (flat ribbon cable).

-Jonathan

Re: show your mic

tony.vasile@...
 

AAAAAAND here's the pic!

Tony KB9A 

On Thu, Apr 19, 2018, 8:33 PM Tony Vasile, Jr. <tony.vasile@...> wrote:
Here is my cigar-box uBitx with a wooden dowel Mic using the kit electret mix element and the Microsoft.

Tony, KB9A 

On Thu, Apr 19, 2018, 5:18 PM Gary Shriver <gshriver@...> wrote:

I know it’s there somewhere!!

 

 

 

 

Re: show your mic

tony.vasile@...
 

Here is my cigar-box uBitx with a wooden dowel Mic using the kit electret mix element and the Microsoft.

Tony, KB9A 

On Thu, Apr 19, 2018, 5:18 PM Gary Shriver <gshriver@...> wrote:

I know it’s there somewhere!!

 

 

 

 

Re: show your mic

馬玉麟
 

Using a section of pen for Mic and PTT switch installation. 

2018-04-20 4:56 GMT+08:00 Matthew S <Rigamurow@...>:

Literally just finished my curmudgeon.  Thanks to K5ESS and N1AW

On Thu, Apr 19, 2018 at 3:18 PM Ashhar Farhan <farhanbox@...> wrote:
What do you know! Mine is uglier than yours. 


On Thu, 19 Apr 2018, 22:53 Bill KC5SB, <blmerideth@...> wrote:
Here's mine.  I made it from an old 9 volt flashlight.


Re: UbitX I2C GPIO Breakouts?

AA9GG
 

Good idea Nick.  On the Atmel, max I2C speed is 400Khz, but a lot of devices do not like this "hi-speed" and you need to run them slower.  Right now I have my bus running at 200Khz and see no delay on my LCD.

On Thu, Apr 19, 2018 at 6:44 PM, NNicholas via Groups.Io <NNicholas@...> wrote:
I have used these chips on many projects and used them to drive led displays, but for this application,  given the slower response of the I2C serial bus, I would stick with the given direct I/O driven LCD display and use the I2C serial to communicate with a second arduino, to add more functions. That way you keep speed, have true multitasking going on, and not only double the io, but you double memory. I plan to add an custom auto antenna tuner to mine, and a 100 watt amplifier , all in the same enclosure. I will be using a second arduino based processor to control both the filtering and switching of the amplifier in and out, and seek and search for best antenna match without having to interrupt the radio operations. That way, when auto tune is turned on, the amp will drop out to low power , the antenna will tune, and then return to the original settings. Like wise as the radio is turned to various bands, the pi filters in the amp can automatically switch with the band.
Nick
N8GIR




--
Paul Mateer, AA9GG
Elan Engineering Corp.
www.elanengr.com
NAQCC 3123, SKCC 4628

Re: Replacement for the blown tda2822

Dexter N Muir
 

Hi Ron

 

Feilding here. Not building uBitx - dead-ended with Bitx-40, QTH with horrendous QRM, and retiree budget stretched with care of 2 grandsons. I contribute my experience and 50+years as a Ham ...

73
Dex, ZL2DEX

Re: anybody tried softrock and hdsdr with Ubitx?

K9HZ <bill@...>
 

Yeah Ian did… and he has a video on Youtube using it…

 

 

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@...

 

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Paul Schumacher via Groups.Io
Sent: Thursday, April 19, 2018 11:50 AM
To: BITX20@groups.io
Subject: Re: [BITX20] anybody tried softrock and hdsdr with Ubitx?

 

Has anyone tried a softrock and hdsdr with Ubitx to get the spectrum and

waterfall display?  (or something similar?)

 

If so, can you please describe how to go about doing it?

 

thanks,


Paul K0ZYV