Date   
Re: Amazing video from ATT archives freely available on youtube

Laurence Oberman
 

Yep, For me the thing about this video was the ingenuity to use the
pivoting metal rods like that to show the wave motion.
Amazing, still cant get over how he came to that idea.

On Thu, Apr 25, 2019 at 4:45 PM Jerry Gaffke via Groups.Io
<jgaffke=yahoo.com@groups.io> wrote:

SWR was about the only thing they could measure 100 years ago,
just run some sort of RF voltmeter along the open wire transmission line to the antenna
and measure the peaks and troughs.

Would be more informative to know the complex impedance of the load,
but SWR is still easier to measure and it's what hams are most familiar with.

Jerry, KE7ER

On Thu, Apr 25, 2019 at 08:01 AM, Tom, wb6b wrote:

Additional comment: The mechanical depiction of SWR video was really interesting, too. Just one point. If you don't have a significant part of a wavelength in a cable or other connection, SWR really is not a factor. Unless you are dealing with microwaves, if you are talking about the impedance match between stages in a transmitter, most likely a "mismatch" in driving the finals (for example, as I often hear described) is not reflecting anything nor has an SWR. But it is still a convenient way to describe impedance matching as so many tools, like smith charts, are built around the concept.

Re: #parts #parts

Doug W
 

You did not say which radio you are interested in.  For the µBITX http://www.hfsignals.com/index.php/ubitx-circuit-description/ is a good place to start.  Toward the bottom of the page under the heading Coil Details you will find information on the inductors.  The component values are shown on the drawings on that page as well.  For the BITX40 you want http://www.hfsignals.com/index.php/2017/11/23/bitx40-circuit-description/
--
www.bitxmap.com

Cant remember is I shared this

Laurence Oberman
 

Hello
If I already shared, apologies
Great value if you have a PC ATX spare supply.
Perfect for may projects.
https://www.amazon.com/dp/B01NBU2C64/ref=cfb_at_prodpg

Re: Are these output watt rating crazy?

Curt
 

Nice power readings - but i would not take them to the bank.  If you have another QRP transmitter, that might let you know if the wattmeter is a tad high.  Honestly a difference of 20% in transmit power isn't noticeable most of the time.  yes don't overdrive the PA to aid reducing the spurious - and nearly every v4 needs 2 spur fixes - one for PA filter network and one of the final mixer (SSB only). 

On 160m I suspect the 80m LPF should handle the third harmonic.  If you might be using a short vertical like me - you may find your 3.6 MHz VSWR into it to be around infinity -- therefore I don't sweat putting 10 watts into 160m.  (Other situations could dreadfully vary). 

Enjoy your new rig, and prepare to do some spurious mods.  Back down the transmit drive a little - and you should be 'acceptable' on 80 and 20 meters. 

73 Curt

FW: [BITX20] Bitx 20 3b "ugly" build

MadRadioModder
 

I don’t know what happened but this note got cut off… it should have gone on to say (it’s important):

 

A couple things to glean from this experience (and to conform to good RF design in general) were:  1) bypass the rails and control lines well… everywhere. Then do it again.  2) Enclose each stage in a shield (simple ones made from circuit boards works perfectly)… this keeps cross talk and spikes from adjacent stages to a minimum. 3) have a good ensemble of test equipment on hand to diagnose and troubleshoot your creation, 4) put the Si5351 as close to the mixers as possible… and use buffers on each of the oscillator output line.  5) Spend extra time matching crystals for the filter…, 6) spend time working the frequency compensation and detailed impedance matching at each stage to make the gain as flat as possible across the desired operating bandwidth (7.0 to 7.3 MHz for the Bix 20 is rather easy… 1.8 to 30 MHz for the uBITx is harder).

 

Ugly doesn’t have to be bad… but it can get ugly if you don’t use good RF construction practices.  Just don’t get disappointed if it doesn’t work the first time.

 

 

From: MadRadioModder [mailto:madradiomodder@...]
Sent: Thursday, April 25, 2019 12:44 PM
To: BITX20@groups.io
Subject: RE: [BITX20] Bitx 20 3b "ugly" build

 

I did this last year… constructed an entire uBITx v4 from scratch but built it in modules for each stage so that I could replace stages with newer experimental designs to try them out.  Two or three others did the same thing.  I designed a backplane with power, agc, control signals that the modules could plug into.  In the end I replaced the front end with a PGA103+ mmic and two PE4306 attenuators, other stages with dual gate ultra-low noise FETs (for AGC control).  Also used a modified version of the K2 crystal filter scheme for variable pass-band.  Then built a second receiver and modified the CEC code fit into a Teensy 3.6 to control both receivers at once (split).  The teensy also does DSP filtering (passband, notch, etc. for both receivers).

 

A couple things to glean from this experience (and to conform to good RF design in general) were:  1) bypass the rails and control lines well… everywhere. Then do it again.  2) enclose each stage in a shield (simple made from circuit boards works perfectly)… this keeps cross talk and spikes from adjacent stages to a minimum

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of n7ql.us@...
Sent: Thursday, April 25, 2019 6:59 AM
To: BITX20@groups.io
Subject: [BITX20] Bitx 20 3b "ugly" build

 

I am getting ready to attempt a Bitx 20 3b build but instead of PCBs I am going to go the "ugly" route. I have many of the parts already and the few I don't I'll buy but it will be cheaper than buying the whole kit. I am wondering if anyone here has gone this route and how well it turned out. Thank you.

_._,_._,_




AVG logo

This email has been checked for viruses by AVG antivirus software.
www.avg.com



--

…_. _._

ALL THE RADUINOS HAVE BEEN SOLD For Sale: 3 Factory Raduinos #ubitx

Jim Sheldon
 

All 3 Raduinos have been sold.

Thanks to those who responded.

Jim - W0EB

Re: FOR SALE

Michael Goins, k5wmg <wmgoins@...>
 

The radio here has been sold. Thanks to all who responded.

Mike, k5wmg




On Thu, Apr 25, 2019 at 12:48 AM ross ingham <eiclan@...> wrote:
Gday Mike,just wondered if you would pack and freight to Australia.  If so I  would love to have it. I have built a v4 but yours looks very nice. If you can freight to Australia  then tell me the costs.  My email is eiclan@....  Cheers Ross Ingham
________________________________________
From: BITX20@groups.io [BITX20@groups.io] on behalf of Michael Goins, k5wmg [wmgoins@...]
Sent: Thursday, 25 April 2019 8:09 AM
To: BITX20@groups.io
Subject: Re: [BITX20] FOR SALE

Sri, all. Meant to send to Ben only. My apologies.

Mike, k5wmg
BELLA GREEN BED AND BREAKFAST<http://www.youtube.com/watch?v>



On Wed, Apr 24, 2019 at 5:33 PM Michael Goins, k5wmg via Groups.Io <wmgoins=gmail.com@groups.io<mailto:gmail.com@groups.io>> wrote:
Hi, Ben,

Here's some photos. It's my understanding it can be programed as is without removal. Well built - I just have some things happing with my business at the moment that won't allow me the time to play with it.

Mike, k5wmg
BELLA GREEN BED AND BREAKFAST<http://www.youtube.com/watch?v>

[0-4.jpg]
[0-2.jpg]
[0.jpg]

[0-3.jpg]




On Wed, Apr 24, 2019 at 3:27 PM Ben WB5QAL/6 <lazylion@...<mailto:lazylion@...>> wrote:
May I see some pictures?  Can I program it in place or does one have to remove the board to reach the connector?

--
Ben Weiss
http://LionsLair.com
Clearlake, CA

On Apr 24, 2019, at 11:45 AM, Michael Goins, k5wmg <wmgoins@...<mailto:wmgoins@...>> wrote:

uBitX upgraded with 3.2" Nextion Display and agc, red commercial cabinet with internal speaker, needs12v at about 3 amps with low standby power. This is a V3 board with the kd8cec v1.1 software. No mic but will include a mike connector and any condenser mike will work with it. The touch-screen display is very cool and essentially self- explanatory.

Bought within the last month and simply will now not have time to play with it. Photos as needed. Complete ready to run radio. Firm on price. $250 shipped.

Mike, k5wmg
BELLA GREEN BED AND BREAKFAST<http://www.youtube.com/watch?v>







Re: Kit-Projects ND6T Ubitx AGC

digger AB3XU
 

Yes, after much trial and tribulation I'm pretty happy, and confident, with my freq and bfo calibration.

-- digger AB3XU

Had audio, then no audio - looks like Q72 dead?

Mark Hatch
 

So V4 here. Audio was working (at least as well as it ever does on v4 if you want speaker output...), Was playing around with a higher impedance speaker (16 vs 8 ohm).still audio . Turned it off, solder speaker wire,, turned it on and no audio.... Bet I shorted the speaker wires somehow and blew the final stage.

Pulled out my Fluke 77, put it in diode mode, and Q72 appears to be a two way diode ;-) between Base and Collector. (i.e. Fluke reports .5 forward volts both ways) Checked the other 2n3904's, and none of them behaved this way. 

Am I interpreting this correct? There is only a 1k resistor between between base and collector... I am much more of a software guy.

If there is consensus here, any suggestions on sourcing the 2N3904? 

73
Mark
AJ6CU

Re: Had audio, then no audio - looks like Q72 dead?

Mark Hatch
 

OK, if this is indeed the problem, found them at Arrow (my newest favorite supplier...). But which variant of MMMBT3904 is right? Looks like main difference is wattage (250-350mw). Get the highest wattage?

Mark

Re: Are these output watt rating crazy?

Jerry Gaffke
 

The 80m LPF is also used for 60m, so the cut-toff freq is high enough to pass the third harmonic of 160m.
This is not a sine wave:
    https://groups.io/g/BITX20/message/48122


On Thu, Apr 25, 2019 at 05:35 PM, Curt wrote:
On 160m I suspect the 80m LPF should handle the third harmonic.

Re: #parts #parts

CiccioSamui
 

Thanks is all I need. 

Re: Kit-Projects ND6T Ubitx AGC

Adrian Chadd
 

I haven't had a chance to poke at the ubitx v4 lately. I'm fixing up a bitx40 for a friend and I'm almost done with that!

-a


On Thu, 25 Apr 2019 at 18:53, digger AB3XU <digger@...> wrote:
Yes, after much trial and tribulation I'm pretty happy, and confident, with my freq and bfo calibration.

-- digger AB3XU

Re: Raduino reinforcement, 3d printed

Kevin Luxford
 

I thank David for his design and for making the .stl file available.  I have just ordered four brackets from a local 3D printing service.  Beats buying a printer with attendant problems of assembling, setting up, adjusting, as well as finding space for it, and avoiding "discussions" with the beloved.
Vy 73,
Kevin,
VK3DAP / ZL2DAP

Re: Are these output watt rating crazy?

Vic WA4THR
 

Very similar results on my V4, a little less than yours on 20 (12w), a little more on 40 (9w), but the pattern is the same and a result of the filters selected on each band relative to the frequency. The rig will transmit anywhere, but should only be used between 80-10m as that is what the filter design is for.

=Vic=

Re: Amazing video from ATT archives freely available on youtube

Tom, wb6b
 

Hi,

It is interesting that the Bell Labs film and the MIT film both came out in 1959. In reading a little about the presenters in the films it looks like this was no accident. The Sputnik satellite launch sent shockwaves through the US and there was a big push for more and better science education. 

Both of these people (and certainly many more) obviously were very smart and interested in improving the physics education of the time. It is a good thing they were there to invent the teaching tools they did. Without the big science push of the day, maybe only the few that attended their lectures personally would have been lucky enough to see these demonstrations. It is fun (and educational) to see these time capsules from the beginnings of the space age.

https://en.wikipedia.org/wiki/John_N._Shive
https://en.wikipedia.org/wiki/John_G._King_(physicist)
https://en.wikipedia.org/wiki/Physical_Science_Study_Committee

A side note. Right after the Bell Labs wave video was another old video by Tektronix on transmission lines. The interesting thing they did was send narrow pulses down a long coax cable and look at the pulses into the cable with open, short and proper termination. Had fun doing the same experiments this evening with a signal generator, scope and a long piece of cable TV coax. Also tried source termination, where the output of the coax is unterminated, but you terminate the input of the coax with a series resistor to the center conductor. I'd used the source termination method for sending digital data down ribbon cables in the past. Was fun to do this again just for play and remind myself it actually works. 

Thanks Laurence for linking the original video, it lead to a bit of fun and learning.

Tom, wb6b

An correction about SD card layout

wb8lga
 

Hi All

There needs to be a correction on the layout of the SD card.

Number 1

    It *.TFT file doesn't need to be the only thing on the root of the card.

    You can have a Folder there also.

     I put all the Nextion display TFT files in the folder.

    Then when we need a TFT file its all ready on the card,

   Just copy the file needed  to the root.

   P.S.  Don't forget to remove any files on the root that's not needed.

   Just one TFT file on the root.


   We put any update of the TFT file on the SD card when there updated.


  WB8LGA

  Charles

Re: An correction about SD card layout

Mark Hatch
 

And if you write using MacOS, it will definitely store "hidden files" on the flash and you will get the multiple file error message. Although there is supposed to be a way to see all hidden files on a Mac, it was far easier for me to slip it into a PC and find those files and delete them....

AJ6CU
Mark

Re: Are these output watt rating crazy?

Mark Hatch
 

Thanks to all the replies! After performing the mod to even up the bands, I suspect that I will need to turn the drive down. And I will keep the watt meter, it might be a tad high, but it is not way off either. I am wondering whether my dully load has a flat impedance response curve too. That could vary the output.

73
AJ6CU
Mark

Re: Are these output watt rating crazy?

Adrian Chadd
 

Which mod did you use to even up the bands?


-a


On Fri, 26 Apr 2019 at 06:30, Mark Hatch <mark2382@...> wrote:
Thanks to all the replies! After performing the mod to even up the bands, I suspect that I will need to turn the drive down. And I will keep the watt meter, it might be a tad high, but it is not way off either. I am wondering whether my dully load has a flat impedance response curve too. That could vary the output.

73
AJ6CU
Mark