Date   
Re: How to change uBitX startup display frequency

Guy WB7SZI
 

Yeah. Ashhar reminded me how to lock a different frequency into VFO A so on startup the display frequency is one I have selected. 
73,
Guy WB7SZI 

Re: uBitx CW transmit problem #ubitx-help #cw #ubitxcw

Evan Hand
 

Other than the straight vs Iambic key setting, I do not have any other suggestions.  It might be RF feedback as that as gotten me in the past.  I worked it out by using a dummy load vs an off center fed dipole.  The dummy load did not have the delay issue.

On the not activating the transmitter, the only way that I know of is to install a switch (or separate fuse as I have) on the PA power supply line. That would allow for using the side tone to practice sending.

73
Evan
AC9TU

uBitx V3 low power continues

Ted
 

This is a follow-up to another thread that is months old. I'm now recovering from cervical spine surgery & attendant complications of infection, so I've had time to repeat tests though not necessarily any clearer mind. Having only 15-20 degrees of rotation of my neck isn't helping, either, with bench work.

To review: a perfectly-functioning radio with typical RF out levels (12w out in 80, 10w in 40, 8w on 20, etc) has devolved to less than a watt on CW on all bands and even less on SSB. The exception is 20 meters, where a couple of watts in CW show up.

Let us assume the finals are fine and that all drivers and pre-drivers are OK. They all get warm, in fact. Suggestions were made to trace the RF thru the LPF array to ensure power wasn't being eaten by a stuck relay or bad filter. I think that this possibility has been eliminated, though I can't explain why the finals get warm and yet the output generally stinks AND worse on one mode than on another.

Again, the SSB signal is far below the CW/dead carrier level, perhaps it is 25-30% of carrier level (according to my oscillscope).  Output at the antenna connection shows approximately the same level as measured at the final transistors.

What dies, prior to Q90, that kills SSB and CW as described?   My sledge hammer works just fine and requires little skill to operate - and at this point makes a better communication tool than my uBitx. I'm not allowed to pick up 15 lbs, though, so that option is on standby. I just don't get it. 


Thanks,

Ted   K3RTA

Re: uBitx CW transmit problem #ubitx-help #cw #ubitxcw

Lou KI5FTY
 

if you are referring to the cw delay (TX->RX) - i have it set at 600 milliseconds.  I just switched it to 0 and verified the settings took by reloading them into memory manager.  Nothing has changed.

Re: uBitx CW transmit problem #ubitx-help #cw #ubitxcw

Lou KI5FTY
 

I see why you thought the transmitter was always on.  the second question I asked was overwritten (at least in my view) by my picture.  the second question was:

is there a trick to get the rig to not transmit for cw practice.  I have tried the menu option of transmit off but no matter how many times I try - I am still transmitting.

Re: uBitx CW transmit problem #ubitx-help #cw #ubitxcw

Lou KI5FTY
 

yes i did - the rig works normally in ssb mode and the rig stops transmitting after 1 second or so after the key is released.

Re: uBitx CW transmit problem #ubitx-help #cw #ubitxcw

Evan Hand
 

There is also a time delay setting to reduce the relay switching that can be changed with the Memory Manager software from CEC.  I am at work so cannot give you the specific value to change.

This will reduce the time the transmitter stays on, however it does not eliminate it.

73
Evan
AC9TU

Re: uBitx CW transmit problem #ubitx-help #cw #ubitxcw

MVS Sarma
 

My reply may not be relevant in this case.


On Wed, 30 Oct 2019, 11:22 pm Mvs Sarma, <mvssarma@...> wrote:
Did you wire the 4.7K pull up resistor as recommended on the "key" jack. Please check. In its absence as you switch on, the rig is likelybto go to tx mode on cw permanently.

Sarma vu3zmv

On Wed, 30 Oct 2019, 11:13 pm , <lscalpati@...> wrote:
Hi - I have completed a uBitx build with my daughter and wee are trying to get it on the air in CW mode.  I am running CEC 1.2 firmware on a v5 board.  There is a problem with the transmission in the CW mode.  after the keyer is released the radio continues transmitting a tone for about 1 sec.  it is reduced in volume but still very strong.  I have attached a spectrum display from my SDR showing a number of dots transmitted and you will notice a tail after each dot.  Any ideas?  Also is there a trick to get the rig to not transmit.  I have tried the menu option of transmit off but no matter how many times I try - I am still transmitting.

Re: uBitx CW transmit problem #ubitx-help #cw #ubitxcw

MVS Sarma
 

Did you wire the 4.7K pull up resistor as recommended on the "key" jack. Please check. In its absence as you switch on, the rig is likelybto go to tx mode on cw permanently.

Sarma vu3zmv

On Wed, 30 Oct 2019, 11:13 pm , <lscalpati@...> wrote:
Hi - I have completed a uBitx build with my daughter and wee are trying to get it on the air in CW mode.  I am running CEC 1.2 firmware on a v5 board.  There is a problem with the transmission in the CW mode.  after the keyer is released the radio continues transmitting a tone for about 1 sec.  it is reduced in volume but still very strong.  I have attached a spectrum display from my SDR showing a number of dots transmitted and you will notice a tail after each dot.  Any ideas?  Also is there a trick to get the rig to not transmit.  I have tried the menu option of transmit off but no matter how many times I try - I am still transmitting.

uBitx CW transmit problem #ubitx-help #cw #ubitxcw

Lou KI5FTY
 

Hi - I have completed a uBitx build with my daughter and wee are trying to get it on the air in CW mode.  I am running CEC 1.2 firmware on a v5 board.  There is a problem with the transmission in the CW mode.  after the keyer is released the radio continues transmitting a tone for about 1 sec.  it is reduced in volume but still very strong.  I have attached a spectrum display from my SDR showing a number of dots transmitted and you will notice a tail after each dot.  Any ideas?  Also is there a trick to get the rig to not transmit.  I have tried the menu option of transmit off but no matter how many times I try - I am still transmitting.

Re: How to change uBitX startup display frequency

Biju Apkrcl
 

How to change vfo A and vfo B on a single push button ? 


On Wed, 30 Oct 2019, 10:54 Ashhar Farhan, <farhanbox@...> wrote:
Flip the vfo from a to b. That saves a and switches to b.

On Wed 30 Oct, 2019, 12:32 AM Guy WB7SZI, <sgbridge@...> wrote:
Haven’t played with my uBitX in over a year and can’t remember how to change the startup display frequency or even if it can be done. 
Pretty sure it’s old age syndrome. 
Appreciate the help. 

Regards,
Guy WB7SZI 

Re: How to change uBitX startup display frequency

Guy WB7SZI
 

Thanks Farhan. Appreciate your help. 

Regards,
 Guy WB7SZI 

Re: bitx40, sk

Robert D. Bowers
 

A more modern design utilizing newer semiconductors might also have much more receiver gain and low noise - a necessity on 2m.

I'd be willing to save up for one of those!

On 10/30/19 1:46 AM, VK3HN wrote:
I think there would be world wide interest in a monoband SSB/CW BiTx2 (144MHz).  I suspect the Bidirectional IF single conversion architecture with garden 2N3904s could be preserved, and a reasonably simple RF amp/mixer and Tx mixer/PA chain designed.  Better RF semiconductors would be needed which would mean sourcing from the big supply houses, but there are lots of modern bipolar options.  If the unit was sold by HFSigs, I don't see why every part in it should be available from the corner store.  That was a characteristic of the BiTx20 and 40 rigs, but it's 2019 now!   

Re: SNA or VNA up 2.4Ghz

erik@...
 

This is what I build

https://groups.io/g/nanovna-users/message/4344

Combined 35mHz to 3GHz VNA  and 0-2GHz SA 
The 2.016GHz cavity filter proved to be simpler to build then expected. I learned some nice tuning tricks
The stiched FFT RBW filters where fun to program
The resistive bridge is the limiting factor in the VNA

Re: SNA or VNA up 2.4Ghz

Ashhar Farhan
 

Interesting observation, ismo,
An individual constructor has some advantage over the commercial builders here, one can get by with cavity and other kinds of strip line filters that are unsuitable for commercial production.
Yet another avenue is to programmatically remove mirror images from readings using software hacks rather than complex frequency manipulations.
On the other hand, it is feasible to build a high quality spectrum analyzer at home. I built one for the HF range. You will find it on the net. The Antuino is a cut down version of that idea.
Wes, W7ZOI's two part article published on the QST and available from his site are a huge wealth of information.
- f
73, f

On Wed 30 Oct, 2019, 11:40 AM Ismo Väänänen OH2FTG, <ismo.vaananen@...> wrote:
MAX2870 from Maxim has the same footprint as ADF4351, but goes from 23.5MHz to 6000MHz. 
Unfortunately optimal layout for either requires a 4-layer board.
For example, all of the black eBay adf4351 I have measured have significant sidebands at +-2x reference frequency due to the sub-optimal two layer board layout. 
Still delightfully cheap and very usable for many things.

Another problem with a wide band spectrum analyzer would be the expensive first mixer and the expensive or annoying to design first IF filter.

All that just means that while doable, it would not be 100usd/pcs for the first revisions. 

One cheap adf based example are the ~50usd 137-4400MHz "simple spectrum analyzer" on ebay end aliexpress. Cheap active mixer as frontend and the IF problem dealt with by using a fixed lowpass filter at the mixer output.
Essentially making it a direct conversion receiver with around 300kHz IF bandwidth. 
The IF is then fed to an ad8307 logamp we know and love.

Re: SNA or VNA up 2.4Ghz

Ismo Väänänen OH2FTG
 

MAX2870 from Maxim has the same footprint as ADF4351, but goes from 23.5MHz to 6000MHz. 
Unfortunately optimal layout for either requires a 4-layer board.
For example, all of the black eBay adf4351 I have measured have significant sidebands at +-2x reference frequency due to the sub-optimal two layer board layout. 
Still delightfully cheap and very usable for many things.

Another problem with a wide band spectrum analyzer would be the expensive first mixer and the expensive or annoying to design first IF filter.

All that just means that while doable, it would not be 100usd/pcs for the first revisions. 

One cheap adf based example are the ~50usd 137-4400MHz "simple spectrum analyzer" on ebay end aliexpress. Cheap active mixer as frontend and the IF problem dealt with by using a fixed lowpass filter at the mixer output.
Essentially making it a direct conversion receiver with around 300kHz IF bandwidth. 
The IF is then fed to an ad8307 logamp we know and love.

Re: bitx40, sk

VK3HN
 

I think there would be world wide interest in a monoband SSB/CW BiTx2 (144MHz).  I suspect the Bidirectional IF single conversion architecture with garden 2N3904s could be preserved, and a reasonably simple RF amp/mixer and Tx mixer/PA chain designed.  Better RF semiconductors would be needed which would mean sourcing from the big supply houses, but there are lots of modern bipolar options.  If the unit was sold by HFSigs, I don't see why every part in it should be available from the corner store.  That was a characteristic of the BiTx20 and 40 rigs, but it's 2019 now!   

Re: How to change uBitX startup display frequency

Ashhar Farhan
 

Flip the vfo from a to b. That saves a and switches to b.


On Wed 30 Oct, 2019, 12:32 AM Guy WB7SZI, <sgbridge@...> wrote:
Haven’t played with my uBitX in over a year and can’t remember how to change the startup display frequency or even if it can be done. 
Pretty sure it’s old age syndrome. 
Appreciate the help. 

Regards,
Guy WB7SZI 

Re: #ubitx-help #parts #ubitx-help #parts

Brad, K7NNR
 

Thanks I completely missed that they were included!

Re: bitx40, sk

Ryan Flowers
 

The BITX40 was my first HF radio ever, and my introduction into so very much. I bought it for $45 when it was without the Raduino, and then added a QRP Labs VFO, then built my own, and modded the heck out of it. For that I am grateful. 

All the best to you Farhan. If you do resurrect it, I'm sure the community will be able to suggest some changes that would be trivial to incorporate.

--
Ryan Flowers - W7RLF
MiscDotGeek.com
Multi Band BITX40
The BITX40 FAQ