Date   
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

CopyguyAZ
 

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

Re: bitx40, sk

RCC WB5YYM
 

The bitx40 was therapy for me when I was diagnosed with a serious medical condition. I knew that through the time of treatment and decision making, I needed a project to keep both my hands and mind busy. The bitx40 was just "what the doctor ordered".  I actually bought a second intending to build it, but the uBITX came along and I purchased one of those as well. The second bitx40 was passed on to a friend, in unopened shipping paper. I credit the bitx40 with helping to preserve my sanity during some pretty tough times. Thanks Ashar Farhan. 

Re: Slow t/r receive recovery #ubitxcw

Curt
 

Mark

I just pulled up excel to do a quick calculation.  The time constant for an RC circuit is T = 1 / (R*C).  note this is the time to reach 67% of steady state value, but gives us a feel for responsiveness. 

T = 1 / (680000 * 2.2 * 1E-6) = 0.67 seconds.

Now defining when this AGC circuit sounds finished to your ears, it could be longer than 1 second.  Use it as a figure of merit to start with. 

If you divide either the R or C by 2, it should settle twice as fast.  maybe select a couple values and use a SP2T to select between them. 

I confess I have no clue the fast and slow AGC times of a typical rig, but you could pick a rig type and see what it lists in manufacturer's spec or a on-line review. 

I do remember seeing the QST article - but I had already installed the VK3YE circuit that I am happy with.  Enjoy your experimenting. 

Curt

Re: bitx40, sk

Robert D. Bowers
 

I completely agree with you.  Actually, I hope that that does occur - a return to more homebrewing and kits.

I won't go into the details, but I have been burned many times by the elitist "If you can't afford the latest and greatest you don't belong!" attitude I've encountered many times since getting my ticket (in 1980).  Homebrewing and kits opens up amateur radio to those who otherwise couldn't afford it - and helps to reduce the sort of attitude I've encountered.  Plus people may make discoveries that otherwise wouldn't be made!  (Wealth does not equal ability or intelligence!!!)

Bob
N4FBZ

On 10/29/19 4:35 PM, Arv Evans wrote:
Farhan

Kits from yourself and Hans have provided encouragement for many to build kit radios
who would possibly have not built anything otherwise.  It has provided many with belief
in their own abilities to make an actual working radio and to package it for their own use. 
Times and parts availability have changed, but the value to ham radio that yourself, Sunil,
and Hans have provided is significant.  Real question seems to be how much the on-line
groups will diminish, or what form they will take in the future. 

Now that many kit builders have found they can actually build their own ham radio
equipment, it may be time to look at bare-boards or even ugly-construction based rig
designs and related discussion groups.  This seems like maybe a reverse evolution,
but there may be enough interest to support something like this.

There are still many of us around who are still designing and building our own homebrew
ham radio equipment. 

Arv  K7HKL
_._


Arv
_._


Re: bitx40, sk

Jack, W8TEE
 

Arv:

Dave Roberts, AA7EE, builds using Manhattan style construction, and his builds are a work of art:

 Inline image

From PCB to dead bug style, all have an element of beauty to me. I also admire (and envy) those who have the EE skills to "roll their own".

Jack, W8TEE


On Tuesday, October 29, 2019, 4:36:38 PM EDT, Arv Evans <arvid.evans@...> wrote:


Farhan

Kits from yourself and Hans have provided encouragement for many to build kit radios
who would possibly have not built anything otherwise.  It has provided many with belief
in their own abilities to make an actual working radio and to package it for their own use. 
Times and parts availability have changed, but the value to ham radio that yourself, Sunil,
and Hans have provided is significant.  Real question seems to be how much the on-line
groups will diminish, or what form they will take in the future. 

Now that many kit builders have found they can actually build their own ham radio
equipment, it may be time to look at bare-boards or even ugly-construction based rig
designs and related discussion groups.  This seems like maybe a reverse evolution,
but there may be enough interest to support something like this.

There are still many of us around who are still designing and building our own homebrew
ham radio equipment. 

Arv  K7HKL
_._


Arv
_._


On Mon, Oct 28, 2019 at 10:39 PM Ashhar Farhan <farhanbox@...> wrote:
This is a little disappointing, but we had to pull the plug on the bitx40 run. The sales were sparse and frankly it had become a bit of a frankenstien.
There were too many connectors that one could plug in the wrong place, we moved from analog vfo (that drifted due to heating of the predriver) to raduino which wasn't well integrated. 

However, it was a bit deal for us all. It was first time we could ship a full ssb transceiver for 50 dollars. This went over and above the ARRL challenge that wanted just parts for $50. We could build, test and ship it for that price point. postage for a challenge and we ended up with going over the $50 mark, but it served many well. Once you had it going, it performed pretty well. it had a triple tuned front-end and the currently favourite 'down conversion' to 12 MHz IF.

We will miss this one, but all is not gone. Sunil continues to ship the bitx20v3 kits which can be modded to 40 meters. if time permits and some in the group volunteer, we could update the original bitx with a more contemporary design while preserving the original's bidirectional, single conversion scheme. Until then, we will continue to see more scratch built bitxs, a kind of return to the roots.

- f 


--
Jack, W8TEE