Date   
Re: Source of small gauge shielded audio wire for a filter #ubitx

DrZ <zehrhj2@...>
 

Pete
I have a Hi-Per-Mite in my uBitx and it makes a huge difference.  I'm not switching it, but I've installed the SCAF in other things such as my KX1 (I had a short article about it in QRP Quarterly last issue) have used DPDTs in those.
I'm purely cw, so in the uBitx I wired the Hi-Per-Mite between the headphones jack and the speaker.  If I want to bypass the SCAF, I use earphones.  Otherwise, I use the speaker.  
73
Howard K4LXY

Re: how to reset the calibration

Jacob Farnes
 

Glad to hear Tim. I hope it will be useful later as well. I'd rather get the code fixed. I need to sit down and noodle through that to find what needs a change.

Sounds like we are both ready in time for CQ WPX SSB

Enjoy your kit!

73 de Jacob AG7CT

Re: how to reset the calibration

Jacob Farnes
 

The Factory software automatically switched LSB to USB when tuning above 10MHz and USB to LSB when tuning below 10MHz.

For whatever reason my uBitx had the wrong BFO frequencies saved as it came shipped. While the screen said USB I was hearing LSB and vice versa. 

I attempted to fix this using the Raduino calibration process, but made the mistake of clicking the encoder switch instead of clicking PTT. After repeating the process a few times the audio out sounded way different (higher overall pitch after each attempt) and I could not hear anything but static out even on known local AM stations.

When I switched to Ian's firmware I got to see the stored frequency for the sideband I was on. (Others may show that but I hadn't the clarity of mind to recognize it like I did the day I switched to Ian's firmware.) The LSB BFO frequency was way up at 12002.xxx

I looked at the code for the default BFO (11995.000). I then tuned the calibrate BFO there and saved by clicking PTT. Tuned around to check if that was USB or LSB now saved for my LSB BFO frequency.  

Using the menu again, I switched mode to USB, then selected Calibrate BFO. (How many times I screwed up here and went into the menu just before and had to set the right offset again... Which seemed to keep changing... :-P) I then found then default in the code (11997.000) USB BFO frequency to be perfect for my filter as well.

Disclaimer: I'm at work away from my uBitx and notes. The default BFO frequencies were correct for my filter. 

Whichbelongs to which sideband I'll leave to the future operators running the tune up process. I'm writing this up in case someone else runs into the same issues in the future.

73 de Jacob AG7CT

Re: Making front panel labels

d p
 

Looks good Vic!

have a look at the method I use. You don’t have to be as careful with the LCD cutting :)

http://projectcasedesignandbuild.blogspot.co.uk/2017/07/printed-facia.html?m=1

Dave
G4UFS

Re: Making front panel labels

 


-- Thanks for the tip. Didn't know you did this stuff Vic. I'm waiting for my kit. Ordered it last moth.
George W3GWM

Re: Source of small gauge shielded audio wire for a filter #ubitx

Randy
 

Have you ever cut into an old USB printer cable?


Randy

Re: Low power output on ubitx #ubitx #ubitx-help

 

At 23-03-18, you wrote:
The relays used for the output filters are put together in a clever way. They use three relays to control four different filters. When KT1, KT2 and KT3 are not energized, it selects the 21-30MHz filter. With KT1 energized it bypasses the 21-30MHz filter and selects the 14-21MHz filter. With KT1 and KT2 energized it bypasses both of those filters and selects the 7-10MHz filter. With KT1, KT2 and KT3 energized it bypasses those and selects the 3.5-5MHz filter. The relays are only energized when transmitting (and only when needed).Â

You have figured it out. I gave up.. Farhan has his mysterious ways of being thrifty. The real reason is as I think is to save one
data out control line from Raduino.

As Jerry said the relays are known to fail so I cut the TX line to filter ralays and linked it to +12V . The relays remain On and
when you tune across bands you can hear them clicking!. Some more power consumption but I can live with that.

LEDs on the board to show the relay status would have been a nice touch! For V2..

Raj


It is a strange configuration but it does save the expense of a 4th relay.Â

Keep in mind now that all the relays are in play when the radio selects an output filter. I had a problem where I had no power out on 30m or 40m. Receive was fine. It ended up that one of the legs on relay KT2 was not soldered. A quick soldering of the pin and I was back in business.Â

BTW, they are not latching relays.Â

Good luck
Mike M.Â
KU4QO

On Thu, Mar 22, 2018 at 9:48 PM, Jerry Gaffke via Groups.Io < jgaffke@...> wrote:
Nope. Â
They are cheap relays.
As they must be on an all band HF transceiver at this price.

They have been known to fail.
Though to be stuck in 80m, seems all three would have to fail.
Seems unlikely.

Jerry

kd8cec if shift

Tim Gorman
 

I finally loaded up the kd8cec software early this morning to give it a
try.

When checking into the KS WX net this morning there was another qso
about 2kc below the net frequency. So I tried Ian's if shift function.

Wow! It works well.

Congratulations to Ian for a truly outstanding contribution to the
usability of the ubitx in a crowded band!

tim ab0wr

Re: Low power output on ubitx #ubitx #ubitx-help

Michael Maiorana
 

The relays used for the output filters are put together in a clever way. They use three relays to control four different filters. When KT1, KT2 and KT3 are not energized, it selects the 21-30MHz filter. With KT1 energized it bypasses the 21-30MHz filter and selects the 14-21MHz filter. With KT1 and KT2 energized it bypasses both of those filters and selects the 7-10MHz filter. With KT1, KT2 and KT3 energized it bypasses those and selects the 3.5-5MHz filter. The relays are only energized when transmitting (and only when needed). 

It is a strange configuration but it does save the expense of a 4th relay. 

Keep in mind now that all the relays are in play when the radio selects an output filter. I had a problem where I had no power out on 30m or 40m. Receive was fine. It ended up that one of the legs on relay KT2 was not soldered. A quick soldering of the pin and I was back in business. 

BTW, they are not latching relays. 

Good luck
Mike M. 
KU4QO

On Thu, Mar 22, 2018 at 9:48 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
Nope.  
They are cheap relays.
As they must be on an all band HF transceiver at this price.

They have been known to fail.
Though to be stuck in 80m, seems all three would have to fail.
Seems unlikely.

Jerry

On Thu, Mar 22, 2018 at 06:35 pm, Mike R. wrote:
Are they latching relays?

_._,_._,_


Description of a built-in ATU for uBitx #ubitx

John <passionfruit88@...>
 

Here is a description of the automatic L-Network auto tuner I built for my uBitx (It can be made to fit other radios).
 
My uBitx is targeted as PM/field portable operations so space and weight are prime considerations. 
 
ATU Design objective: 
 
1. Fits in the limited space of my Jameco case (Jaycar case here in Oz), on my second level board.
 
2. Tunes long wire and EFHW (worst case with the help of a 9:1 balun).
 
4. Works 80m to 10M.
 
3. Memory tune to save power and time.
 
4. Negligible power consumption when not tuning.
 
5. Must integrate with the extra (planned) features like SWR measurements, Finals' current limiting, and power supply monitoring, and more.
 
Therefore I settled on a second Arduino and an L-Tuner network despite some limitations when compared to T or Z-match networks that seem to require three adjustable elements for 80 to 10M coverage.
 
The 2nd Arduino has the following advantages: at AU$6 landed in Australia it is much cheaper than extra I2C analogue and digital I/Os, plus it gives me another 30K of programming space and 1K of EEPROM for memory tuning, can be put in slow power mode when not tuning as I use the Mini Pro version (no USB port), and communicates via the I2C bus with the Raduino.
 
First I needed an SWR meter and the Don Cantrell (ND6T) circuit was a perfect match. I made it as a daughter board that plugs directly into the connector after the LPFs. (http://bitxhacks.blogspot.com.au/2017/03/nd6ts-forward-and-reverse-power-meter.html). Thank you Don for a reliable solution.
 
Browsing the internet and looking at previous solutions like the SLT+ and the Altoid Long Wire Tuner, I settled on 6 inductance values.
 
Switching the inductance could be done with relays, but that means 5 bi-stable relays and ten digital outputs. Same issue with the variable capacitors.
 
I decided to use an RC servo controlling a mylar variable capacitor and another one controlling the rotary switch for the coils.
 
The first challenge was to have a way of switching the capacitor from the antenna side to the TRx side. One option was a bi-stable relay, or, the solution I settled on, was to use a double wafer rotary switch with 12 positions and dedicated 6 of them to the capacitor on the input and 6 on the output. 
 
Therefore I need two digital ouputs for the PWM generation for the servos and one for cutting the power off to the servos (common positive supply).
 
My main concern was the possibility of the servos not handling RFI. But in the end they were easy to tame.
 
The next challenge was to find a servo that could do 360 degree rotation (or at least 345) to cover all 12 contacts on the rotary switch.
 
There a quite a few servos doing 180 degrees but I could not find one that did 360 degrees. Please note there are many so-called "360 degrees" servos available but they are "continuous rotation" servos and do not move to a position, just rotate at a certain speed, with no position feedback. 
 
The first solution was a 2:1 gearing and a 180 degree servo. It worked but was not very reliable due to the extra backlash even with a larger servo to compensate for the power loss in the gears.
 
Luckily there are now "Sail Winch Servos" available in 1, 1.5, 2 and more turns, but still with position control. At the end I used the 1 turn version quite successfully a "GWS S125 1Turn 2BB Sail Winch Servo".
 
The following and probably key challenge I faced was to ensure that the servo would settle pretty much centred on the rotary switch contacts. The angular resolution of the servo is sufficient for this but I needed repeatability. Otherwise I would destroy the contacts through arcing.
 
Since I control the supply of RF power to the antenna I can cut the power off when I change contacts on the rotary switch and the solution was to use a digital input on the Arduino to measure when the contacts are established or not, and thereby form a map of the location of the contacts relative to the angular position of the servo. Since when the contact is established I get a short to ground through the coils. A pair of 1MOhms resistors to feed the 5V and connect to the Arduino pin,  works very well.
 
I build that contact map once at first tune and use it thereafter until power down. It may be possible to store is in EEPROM but I haven't checked it's stability over time and temperature.
 
When I move the servo from one contact to the next I can again check at what angle the contact is established or lost to compensate exactly for the backlash. A bit of software and it works quite reliably.
 
I shielded the ATU with PCB plates to prevent stray RF, but apart from the capacitor servo which occasionally displayed small jitters, the rest did not really need it and worked quite well without.
 
So the main components are: Arduino mini pro or nano, variable capacitor and micro servo, rotary switch 12 positions with two wafers (it could be one wafer and less positions and a bi-stable relay) and a "one turn sail servo", a P-Channel Mosfet for servo supply, a 5V regulator dedicated to the servos' power, the components for the ND6T SWR and Power bridge.
 
I use the following I/Os on the 2nd Arduino: 4 digital I/Os of which 2 are PWM, plus two analogue inputs, the I2C (A4/A5) lines.
 
So I have enough I/Os left for the other functions I want to implement.
 
Performance: With a 21m (69') long wire and a 10m (33') counterpoise on the ground I can tune all bands (I don't know about 60M, as we still don't have access here in Australia) with an SWR of under 2.
 
A full tune sequence takes 32 seconds if the matching coil is in position 12, and a memory tune is around 3 seconds. At first tune after power-up, there is an additional delay of 15 seconds for the rotary switch contact mapping.
 
Total parts cost is around AU$130 (US$100 approx.), but a lot cheaper in the USA and other countries I am sure and quite a few items could be in the junk box.
 
I will produce a schematic for the ATU and clean my code to publish the source.
 
Critique of the design now that is is completed:
- the winch servo adds 50g plus coupling of around 30g is a fair amount of weight, but the total built is still under 2Kg at 1.25Kg or 2.8 Pounds.
- a single bi-stable relay instead of the second wafer for switching the capacitor over may be a simpler solution, and leave more steps for the inductance.

Hope this helps,
 
All the best,
 
73, John (VK2ETA)

Pictures attached to show the following:
 
1. A complete view of the unit with the shields in place. Also the Android hands free headset (with modified software for push-on/push-off PTT).
 



2. Second Board (double sided fibreglass as a ground plane, plus sections of vero board) with the MAX9814 AGC, the SSM2167 mic compressor, the ATU circuit and Arduino.




3. The back of the unit with the ATU toroids, variable capacitor (the angling is to align it with the servo's angular range), the SWR/Power bridge. Note that I use three toroids as I tried to minimise losses and prevent high voltages since I do not short the unused turns (I am not sure if this is critical).



4. A top view of the coupling of the micro servo and mylar variable capacitor.

 
5. A top view of the rotary switch, toroids and the contact detection circuit.

 
6. The SWR bridge daughter board's back with it's female header to provide solid ground connection and mechanical rigidity.


7. Tuning completed . P = forward power, R = SWR .... front panel labels due soon

Re: ubitx michrophone

joseph.cunningham50@...
 

thanks brian regards joe g0liq

Re: Source of small gauge shielded audio wire for a filter #ubitx

chris gress <Chrisg0wfh@...>
 

I have found they are not screened chris

On 19 Mar 2018 00:19, "Nik VK4PLN" <nickpullen@...> wrote:
Hi, Chop up a set of cheap in-ear headphones....

See my new board, awating delivery:  https://groups.io/g/BITX20/topic/14920831?p=Created,,,20,1,0,0
Ill post up pic of it installed once done.
73 Nick.

Re: How to test speaker resistance

Gordon Gibby <ggibby@...>
 

If I recall my physics, I believe the formulas for resonance for a mechanical circuit are the same math equations as those for an electrical circuit.

Because the speaker is a transducer, there is a transference between mechanical & electrical resonance.


On Mar 23, 2018, at 01:01, Raj vu2zap <rajendrakumargg@...> wrote:

Jerry,

The speaker is like a LC circuit and it has a resonance. The frequency is dependant on the
mass of the cone and the elasticity of the suspension (including the enclosure air).

The for formula is the same as LC resonance.

To determine the mass I used to measure the first a peak in voltage and then attach a
know weight like 1gram and get a second peak. Using these two we can calculate the
mass of the cone and with that know the elasticity.

I used to change the resonance by spray painting the cone a little! I have seen woofers
that had paint and sand type particles on the cone to increase its mass!

In bass reflex the box and the duct has it own resonance which shows up in the tests.

https://www.electronics-notes.com/articles/audio-video/loudspeaker/speaker-cone-resonance.php

Raj

At 22-03-18, you wrote:
Interesting, though raises more questions than it gives answers to.

The graphs show different speaker responses, mostly for no particular reason.

At the start he defines resistance and impedance as two different things (probably should read resistance and reactance),
then in the graphs it properly shows complex impedance as ohms of impedance with a phase angle,
which is the combination of resistance and reactance.

More puzzling to me, he shows a self resonance at 130 hz or so in the first graph,
and the phase angle flips there from positive to negative just like an LC circuit.
But "impedance rise due to voice coil inductance" in the second graph doesn't take over till 1khz and beyond.
What exactly is going on at self resonance?   That's a central concept here, and left unexplained.
And seems a resonance at 150 hz would be extremely disruptive to the sound spectrum we hear.

He shows a base-reflex speaker's impedance to have two peaks (at two different frequencies),
then claims that if they are the same height (same max impedance on both peaks)
then the "resonant frequency of the speaker matches the resonant frequency of the box".
But the frequencies certainly don't match.

Not sure I trust anything in the writeup now, but that second graph is interesting.
Shows his nominally 4 ohm speaker to have a dc resistance of 3.2 ohms
and a resonance at 30hz of about 31 ohms.  At resonance, it's far from 4 ohms.

Conclusion:  A 4 ohm speaker can have drastic variations in impedance
over the audio frequency range.

Jerry, KE7ER


On Thu, Mar 22, 2018 at 06:03 am, Raj vu2zap wrote:
Worth reading this page.

http://audiojudgement.com/speaker-impedance-curve-explained/

Re: How to test speaker resistance

Jerry Gaffke
 

It all makes sense.
But was surprised at how cleanly the mechanical resonance showed up in the electrical test,
looking for all the world like an LC circuit.
Not something I had thought a lot about.


On Thu, Mar 22, 2018 at 10:00 pm, Raj vu2zap wrote:
Jerry,

The speaker is like a LC circuit and it has a resonance. The frequency is dependant on the
mass of the cone and the elasticity of the suspension (including the enclosure air).

The for formula is the same as LC resonance.

To determine the mass I used to measure the first a peak in voltage and then attach a
know weight like 1gram and get a second peak. Using these two we can calculate the
mass of the cone and with that know the elasticity.

I used to change the resonance by spray painting the cone a little! I have seen woofers
that had paint and sand type particles on the cone to increase its mass!

In bass reflex the box and the duct has it own resonance which shows up in the tests.

https://www.electronics-notes.com/articles/audio-video/loudspeaker/speaker-cone-resonance.php

Re: Gallery

Mike Woods
 

Probably - there are 4000 of these kits now in the hands of constructors!   I bet there are some pretty interesting builds out there!

Mike ZL1AXG

On 23/03/18 5:52 PM, Thomas Sharka via Groups.Io wrote:
Very nice! May you receive many contributions.
 


Sent from Yahoo Mail. Get the app


On Friday, March 23, 2018 12:16 AM, Mike Woods <mhwoods@...> wrote:


The ubitx.net website now incorporates a build gallery.  I figure this could be very handy for new constructors to source ideas for enclosures, layout and labelling.
It can be found as the last item in the main menu ... Gallery of uBITx Builds
I am sure that there are some more fine build examples out there.  If you want to send me a few photos I will look to include your µBITx build in the gallery.  I reserve the right to not include your build is a bit rough and doesn't meet my expectations of being a good role model for others!
73 Mike ZL1AXG ubitx.net
--
Mike Woods
mhwoods@...



--
Mike Woods
mhwoods@...

Re: How to test speaker resistance

 

Jerry,

The speaker is like a LC circuit and it has a resonance. The frequency is dependant on the
mass of the cone and the elasticity of the suspension (including the enclosure air).

The for formula is the same as LC resonance.

To determine the mass I used to measure the first a peak in voltage and then attach a
know weight like 1gram and get a second peak. Using these two we can calculate the
mass of the cone and with that know the elasticity.

I used to change the resonance by spray painting the cone a little! I have seen woofers
that had paint and sand type particles on the cone to increase its mass!

In bass reflex the box and the duct has it own resonance which shows up in the tests.

https://www.electronics-notes.com/articles/audio-video/loudspeaker/speaker-cone-resonance.php

Raj


At 22-03-18, you wrote:
Interesting, though raises more questions than it gives answers to.

The graphs show different speaker responses, mostly for no particular reason.

At the start he defines resistance and impedance as two different things (probably should read resistance and reactance),
then in the graphs it properly shows complex impedance as ohms of impedance with a phase angle,
which is the combination of resistance and reactance.

More puzzling to me, he shows a self resonance at 130 hz or so in the first graph,
and the phase angle flips there from positive to negative just like an LC circuit.
But "impedance rise due to voice coil inductance" in the second graph doesn't take over till 1khz and beyond.
What exactly is going on at self resonance?   That's a central concept here, and left unexplained.
And seems a resonance at 150 hz would be extremely disruptive to the sound spectrum we hear.

He shows a base-reflex speaker's impedance to have two peaks (at two different frequencies),
then claims that if they are the same height (same max impedance on both peaks)
then the "resonant frequency of the speaker matches the resonant frequency of the box".
But the frequencies certainly don't match.

Not sure I trust anything in the writeup now, but that second graph is interesting.
Shows his nominally 4 ohm speaker to have a dc resistance of 3.2 ohms
and a resonance at 30hz of about 31 ohms.  At resonance, it's far from 4 ohms.

Conclusion:  A 4 ohm speaker can have drastic variations in impedance
over the audio frequency range.

Jerry, KE7ER


On Thu, Mar 22, 2018 at 06:03 am, Raj vu2zap wrote:
Worth reading this page.

http://audiojudgement.com/speaker-impedance-curve-explained/

Re: Gallery

Thomas Sharka
 

Very nice! May you receive many contributions.
 


Sent from Yahoo Mail. Get the app


On Friday, March 23, 2018 12:16 AM, Mike Woods <mhwoods@...> wrote:


The ubitx.net website now incorporates a build gallery.  I figure this could be very handy for new constructors to source ideas for enclosures, layout and labelling.
It can be found as the last item in the main menu ... Gallery of uBITx Builds
I am sure that there are some more fine build examples out there.  If you want to send me a few photos I will look to include your µBITx build in the gallery.  I reserve the right to not include your build is a bit rough and doesn't meet my expectations of being a good role model for others!
73 Mike ZL1AXG ubitx.net
--
Mike Woods
mhwoods@...


Gallery

Mike Woods
 

The ubitx.net website now incorporates a build gallery.  I figure this could be very handy for new constructors to source ideas for enclosures, layout and labelling.

It can be found as the last item in the main menu ... Gallery of uBITx Builds

I am sure that there are some more fine build examples out there.  If you want to send me a few photos I will look to include your µBITx build in the gallery.  I reserve the right to not include your build is a bit rough and doesn't meet my expectations of being a good role model for others!

73 Mike ZL1AXG ubitx.net

--
Mike Woods
mhwoods@...

Re: Receive Birdies

VK3HN
 

Mike

I built a Progressive Receiver (W7ZOI) last year with si5351 and stayed with the original dual conversion frequency mixing scheme, a first (tuneable) IF of 3.5-4MHz, second IF 9MHz.  I used all 3 si5351 clocks, first for VFO, second for heterodyne osc, 3rd for BFO.  It was riddled with birdies, unusable.  First I built a crystal BFO and buffer, eliminating the need to use the third si5351 clock.  Made almost no discernible difference.  Finally I ditched the dual conversion scheme and reconfigured it into a single conversion superhet with high side VFO.  Problem fixed.   Well almost.  There are still a few odd birdies, but just a handful, all are well below the usual received signals.  I now use this receiver frequently on 160 to 40m and it works well.  has some gain distribution issues but that's a different problem.  

I suspect the clocks are rich in harmonics and that by placing f-VFO above f-IF they no longer bother me. 

My rx has tight receive BPFs.  It could be shielded better.

I also started scratch building a uBitx and got it receiving, kind of, not really, lost interest for another build, will come back to it one day. 

Regards  Paul VK3HN.  

Re: BITX QSO Afternoon/Evening, Sunday, March 25, 3PM & 7PM Local Time, 7277 kHz in North America, 7177 kHz elsewhere.

Bruce Anderson
 

There’s going to be more than a little contesting going on at that time, CQWW WPX-SSB ends at 03 25 2359:59 GMT, the Euros are going to be all over 40 meters.

73 de Bruce W1BWA