Date   
Re: Lna #ubitx

MVS Sarma
 

LNA at front end with out having BPF  for band selection would be catastrophic. Power from radio broadcasts will overload such LNA and make mess.

Better to use multi-band 3 section filters and then use LNA with attenuator , if needed.  Farhan says  we dont need  band filters as ubitx uses dual conversion.


sarma  vu3zmv


On Tue, Mar 3, 2020 at 11:31 AM Evan Hand <elhandjr@...> wrote:
There have been multiple messages on this site covering the addition of an RF LNA to the input of the uBitx.  All conclude that it does not make a significant difference.  That is not the case with adding amplification in the audio sections,, with an add on audio power amp being the most common.

If you find that you do not have enough speaker volume, I would add the power amp, most common are based on the TDA2030.  Example :
https://groups.io/g/BITX20/message/76640

FWIW
73
Evan
AC9TU

Re: Only noise when connected to the antenna #v6

Jonathan Kayne, KM4CFT
 

After some thought, I have decided that I will be doing another revision of the board that will be built in a modular fashion. I intend to connect RF lines together with SMA connectors to preserve signal integrity and use plain old stranded wire to run control signals. 
This will make it more easy to experiment with and isolate any potential noise problems. 
I also plan on adding two ground planes on both sides connected with via stitching to help with the noise and eliminate ground loops!
I will post again with my progress as I think the group might find it interesting!
73,
-Jonathan, KM4CFT

Re: Lna #ubitx

Evan Hand
 

There have been multiple messages on this site covering the addition of an RF LNA to the input of the uBitx.  All conclude that it does not make a significant difference.  That is not the case with adding amplification in the audio sections,, with an add on audio power amp being the most common.

If you find that you do not have enough speaker volume, I would add the power amp, most common are based on the TDA2030.  Example :
https://groups.io/g/BITX20/message/76640

FWIW
73
Evan
AC9TU

Re: uBITX6 assembly instructions

Evan Hand
 

Bill,

I believe that the issue is prior look up on the HFSignals.com location.  You need to be sure to not take the default url that you found before, rather type out the hfsingnals.com in the url, and insure that there is nothing beyond the .com.  That will take you to this page:
https://www.hfsignals.com/ 

Try the above link

FWIW
Evan
AC9TU

automatic side band switch.

Richard
 

The site information says that the sideband automatically switches at 10 mhz.  I just put my V6.1 together and am listening to a net on 80 mtrs. using the front panel usb/lsb  tab the side band stays at LSb no matter what I do. I can't at this time find another station above 10 mhz to see what happens. Is switching so automatic that I can not do it manually. If so why do I have the option on the front panel ?
Inquiring minds want to know
 Richard
KE5NCR

Re: Only noise when connected to the antenna #v6

Curt
 

Jonathan

I am less troubled by noise and leakage into the receiver than not being able to receive signals. Sweeping an IF signal into the final mixer should produce audio output when it gets within so many kHz of the LO.

Sometimes its desirable to disconnect things and test individual circuit blocks, a method used by many scratch builders.

The specific arrangement of the hardware can lead to coupling between things, but these should be smaller than a large RF signal.

Okay there is one thing that can wreck a circuit, a regulator that is oscillating,  but easy to notice that with a oscilloscope.

Do isolate the circuit functions in question,  and examine those. I even once troubleshooted a superhet receiver by touching my HF antenna to the IF section, as there were signals there. If not, you have nice instruments there.

Curt

Re: uBITX6 assembly instructions

support@...
 

Hello Bill

https://www.hfsignals.com/index.php/ubitx-v6-assembling-the-full-kit/

This link is active and can be accessed. Please use another browser in case you have any difficulty to open it. Copy paste this link in case you are not able to click the link from within the group.

This link provides a step by step instruction for assembling your V6 uBitx and is very easy.

All the best.

Thomas
--
Support@...

Re: TX frequency is 1.2 kHz off #bfo #calibration #cw #v6

Curt
 

Juha

sounds like have made nice progress!  yes the CW on transmit is a bit different - it tends to respond a bit slow and there is the matter of not pausing too long, lest the relay open up and we get the delay again.  I have somehow learned to do CW with it.  on receive, I installed a SCAF tunable bandwidth audio filter. 

enjoy your rig!

Curt wb8yyy

Re: Lna #ubitx

Curt
 

worthwhile to experiment, but the ubitx is quite sensitive when connected to a reasonable size antenna.  if your antenna is working, you should hear the noise level rise a little when the antenna is connected. 

possibly a preamp may help a little on 28 MHz, but it should not change much.  usually adding gain harms a receiver, once a receiver has enough gain.  some folk are boosting audio gain a bit, but generally not much need anywhere else. 

of course report your results. 

73 curt

Re: Only noise when connected to the antenna #v6

Dr. Flywheel
 

Are you using your SA Tracking Generator to check the behavior through the signal path? Did you measure the actual frequencies of the three OSC outputs?

---Ron
N7FTZ

On Mon, Mar 2, 2020 at 4:02 PM Jonathan Kayne, KM4CFT <jzkmath@...> wrote:
If I trace the signal through and there is noise appearing in the first stage then I don't think it's a matter of alignment. Plus I have tried that numerous times and it never helped. 
At this point I am literally connecting the spectrum analyzer to the antenna connector. Disconnect the antenna switching section from the rest of the circuit and it's clean. Connect the LPF plus 1st conversion to the circuit and the noise floor goes above the -90 dBm signal. I need to figure out what is raising the noise floor at the first stage which should fix the issue. 

Re: Only noise when connected to the antenna #v6

Jonathan Kayne, KM4CFT
 

If I trace the signal through and there is noise appearing in the first stage then I don't think it's a matter of alignment. Plus I have tried that numerous times and it never helped. 
At this point I am literally connecting the spectrum analyzer to the antenna connector. Disconnect the antenna switching section from the rest of the circuit and it's clean. Connect the LPF plus 1st conversion to the circuit and the noise floor goes above the -90 dBm signal. I need to figure out what is raising the noise floor at the first stage which should fix the issue. 

Re: Only noise when connected to the antenna #v6

Dr. Flywheel
 

More than likely, your IF oscillator frequency is off and the Xtal filter attenuates the incoming signals as a result. Try calibrating the BFO oscillator.

73's
Ron
N7FTZ

On Mon, Mar 2, 2020 at 3:03 PM Jonathan Kayne, KM4CFT <jzkmath@...> wrote:
It seems that somehow there is a bunch of noise making it into the radio. Just running it through the 1st conversion seems to bring the noise floor up enough for any reasonable signal to have adverse affects on the performance as seen by these two pictures! This was at the antenna connection so somehow noise from the 1st conversion is bleeding into the circuit making it too noisy to use. 
Any ideas on how to fix?

Re: Only noise when connected to the antenna #v6

Jonathan Kayne, KM4CFT
 

It seems that somehow there is a bunch of noise making it into the radio. Just running it through the 1st conversion seems to bring the noise floor up enough for any reasonable signal to have adverse affects on the performance as seen by these two pictures! This was at the antenna connection so somehow noise from the 1st conversion is bleeding into the circuit making it too noisy to use. 
Any ideas on how to fix?

Re: uBITX6 assembly instructions

Bill Leaming
 

On Mon, Mar 2, 2020 at 02:31 PM, Rick Beres wrote:
ubITX V6
Unfortunately there is no link to those pages to be found there.

Re: uBITX6 assembly instructions

Rick Beres
 

It may be hard to find assembly page. Here is a link to iy.

https://www.hfsignals.com/index.php/ubitx-v6-assembling-the-full-kit/

73s VE6CW

 

From: BITX20@groups.io <BITX20@groups.io> On Behalf Of kbtgw
Sent: March-02-20 2:54 PM
To: BITX20@groups.io
Subject: [BITX20] uBITX6 assembly instructions

 

Hi, just got the uBITX6 full kit but I do not think shacking the box will get it assembled.
Can someone please lead me to the assembly procedures !
Some of us are slow learners.
  Les,  K2TGW    k2tgw2arrl.net

Re: uBITX6 assembly instructions

Bill Leaming
 

Les, a few weeks ago someone posted a link to the complete assembly instructions for the uBITX v6 but I'll be darned if I can find it now. For some strange reason there is no link to that article despite being hosted at hfsignals.com ... Go figure <sigh>

However, I assembled mine without recourse to the instructions in about two hours. It would have gone faster but I had to take a couple of breaks to fix supper, eat and clean up.

Absolutely no soldering is required as everything has been done already! It's really nothing more that checking off the parts on the included manifest to make certain that you received everything.

I only had to puzzle out two things: 1) where to plug in the connector from the encoder and 2) where to plug in the speaker... ;)

The encoder plugs into the arduino board (it is keyed so you can't connect it backwards). The speaker plugs into the two pin header at near the volume control.

Re: uBITX6 assembly instructions

Rick Beres
 

Go to HF SIGNAL web page and click on ubITX V6. There you will find assembly instructions.

Have Fun

Ve6cw  

 

From: BITX20@groups.io <BITX20@groups.io> On Behalf Of kbtgw
Sent: March-02-20 2:54 PM
To: BITX20@groups.io
Subject: [BITX20] uBITX6 assembly instructions

 

Hi, just got the uBITX6 full kit but I do not think shacking the box will get it assembled.
Can someone please lead me to the assembly procedures !
Some of us are slow learners.
  Les,  K2TGW    k2tgw2arrl.net

Re: Lna #ubitx

barry halterman
 

Mike, I used the circuit from W8DIZ kitandparts, HF rf amp1.3, under the rftools tab. Installed it just before the 4 toroid filter in the Rx path. I do remember the noise floor being higher and so were the signals. The Rx having no acg and the increase in sensitivity made it unbearable to listen to. Then at night I would pick up SW am stations constantly in the background. Since then, I have removed the amp.
Good luck and have fun...
Barry
K3BO




On Mon, Mar 2, 2020, 4:21 PM Mick <Mgsebele@...> wrote:
Thanks Barry,
I have a little 12 vdc LNA that I tried inline between the radio and antenna ( no tx of course). It seemed to amplify the noise more than the signal. I’m not sure if this is the correct amp for this application.
 It is a 60 dB gain .1m to 2g hz rf pre amplifier.
73
Mick VA3EPM 

uBITX6 assembly instructions

kbtgw
 

Hi, just got the uBITX6 full kit but I do not think shacking the box will get it assembled.
Can someone please lead me to the assembly procedures !
Some of us are slow learners.
  Les,  K2TGW    k2tgw2arrl.net

Re: Lna #ubitx

Mick
 

Thanks Barry,
I have a little 12 vdc LNA that I tried inline between the radio and antenna ( no tx of course). It seemed to amplify the noise more than the signal. I’m not sure if this is the correct amp for this application.
 It is a 60 dB gain .1m to 2g hz rf pre amplifier.
73
Mick VA3EPM