Date   
Re: VOM Advice?

Jack, W8TEE
 

One feature I find really useful is the ability for the unit to "beep" when doing continuity checks. Without that feature, I seem to lose my test points when I go to look at the meter's display. With the beep feature, it can keep the leads where they belong rather than slipping off the part under test and releasing the magic white smoke from the most expensive part on the board.

Jack, W8TEE

On Thursday, June 14, 2018, 11:11:52 PM EDT, Tim Gorman <tgorman2@...> wrote:


For most anything you'll do with the ubitx you don't need an expensive
desk meter.

this one:
www.ebay.com/itm/Digital-Voltmeter-Ammeter-Ohmmeter-Multimeter-Volt-AC-DC-Tester-Meter-US-Seller/271496690158?hash=item3f3676b9ee:g:qgUAAOSwHnFVkYPk

is representative of one that has lots of functions. It's a lot like
the one I use much of the time. PLEASE don't hook the test leads up the
way it is shown, it won't work!

There is a huge gap in its current measuring scales, from 200ma to
10amp in one big jump, but that will probably get you by.

tim ab0wr

On Thu, 14 Jun 2018 19:11:08 -0700
"Mark M" <junquemaile@...> wrote:

> Sorry if this is a bit off topic but it is related to uBitX hacking...
>
> My ancient, el-cheapo VOMs (Radio Shack/Harbor Freight freebies) all
> have pretty much ceased working so I'm looking for some suggestions
> about suitable replacement units. I'm not looking for lab quality,
> just something for a hobbiest/amateur hardware hacker (like for
> modifying the uBitx). I'd like to find something that's reliable and
> reasonably accurate for a few 10's of dollars. I see many units on
> Amazon for around that but don't know which ones would be good buys.
> So, any advice from y'all?
>
> Thanks & 73....     Mark    AA7TA
>
>
>



Re: Transmitter Mods

Sajid Rahum
 

Hi Rob

Doing these mods this evening.  Much appreciated Howard's parts.

For the tee pee - let me know how you did it.

I am going to gently put the solder iron on right side and try to lift it as soon as solder start to give.  Any suggestions will be appreciated.

Re: Can't get my uBitX to transmit CW on the Dial frequency

 

As Tom, WB6B suggests, an important reason for displaying the TX frequency in CW modes is that you need to know that when you
hit that key that you are transmitting in-band. It is more important to know your TX frequency than your RX frequency and this is also 
the convention used on most commercial HF rigs. 

I only had the original uBITX code installed for a day but I do seem to recall that there was no explicit CW mode.  
The CEC code does have explicit CWU and CWL and as I stated, once you have a station properly tuned you should be able to toggle
back and forth between the two CW modes and still have the received station in the filter passband. There may be a slight shift in received tone
(nothing is perfect) but it should be very close.  

I also believe that what Tim AB0WR suggests regarding changing the BFO frequency is correct.
If you haven't moved the VFO the frequency it's frequency shouldn't change except to apply a +/- offset equal to the sidetone frequency on RX (the TX carrier frequency stays the same and should be the dial frequency as stated above). Switching back and forth  from CWU to CWL should change the BFO frequency (which only affects RX) to allow the switching of the selected sideband. The change in BFO frequency plus the application of the RX offset with the correct sign to the VFO determines the change in RX frequency on the CW mode change. 

If you must display the actual RX frequency as the dial frequency then it has to change when you change from CWU to CWL. Changing the TX frequency
as it currently does is incorrect.  Also I would suggest that if the dial frequency remains the RX frequency, then the display should change on TX  to show the
TX frequency (i.e. carrier frequency) and then back again on RX. 

As Allard, PE1NWL stated in an earlier posting on this same topic ... we went through pretty much the same discussion on the operation of the BITX40
and came to the conclusion that the display frequency on both CWU and CWL should be the TX (carrier frequency) and that is what Allard implemented in
his Bitx40 code. 

Cheers 

Michael VE3WMB 

Re: VOM Advice?

bobolink
 

For the complex digital mode signals you might be interested in a “true rms” voltmeter. I paid a little extra for that (about $12) from banggood.
I haven’t tested it against my Fluke. That would be an interesting comparison.
true-rms

Re: Can't get my uBitX to transmit CW on the Dial frequency

 

One more thing ...

Just to simplify the discussion, what we have here are two issues :

1)  switching from CWU to CWL on CEC V1.08 incorrectly changes the TX frequency (it should remain fixed) wheres it should be the RX frequency
that moves due to the change in sign of the applied RX offset and the change to the BFO frequency to match the selected sideband. 

This is a bug. 

2) The issue of what frequency should be displayed. (Currently it is the RX frequency).

   Options are :
   
   1) Display Tx frequency - will not change on display when moving between CWU/CWL. Will not change on TX vs RX. (Recommended) 

    2) Display Rx Frequency - must change when switching CW sidebands to be accurate.
        Recommend it change to TX frequency and back when switching between TX and RX so operator knows what actual carrier TX frequency is. 

Cheers

Michael VE3WMB 


 

Re: VOM Advice?

Karl Heinz Kremer, K5KHK
 

Jack is right, it should beep, and it should also beep right away, without any delay: I have to meters, one (actually a relatively cheap true RMS pocket meter from Banggood) beeps right away, my more expensive one has a small delay, and when you are testing for conductivity, you will wait until it beeps, but if you are testing for non-conductivity, the instant feedback is much better than to decide if you've waited long enough :) 
--
Karl Heinz - K5KHK

Re: Transmitter Mods

Rob Snow
 

Sajid,

The teepee was the hardest part for me.  My first thought was to heat one side and try to lift it, but that didn't work as the other side still held tough.  Next I wicked both ends and then tried the same thing again and got some movement.  Finally, I just applied pressure to the side and heat and slid it off the pad completely and started the tee pee fresh.  My inductor is a squat little thing so I soldered it down as a tower on one pad and then re-applied the resistor as a bridge.

My biggest concern was either a) destroying the resistor with heat, or b) flicking it off and sending it into the ether while trying to desolder.  I have a SMD resistor sampler pack and I think I read it as being a 102 (1k ohm), so I had that as a fallback and maybe made me a bit braver on my application of heat and force.


On Fri, Jun 15, 2018 at 7:24 AM, Sajid Rahum via Groups.Io <zs735@...> wrote:
Hi Rob

Doing these mods this evening.  Much appreciated Howard's parts.

For the tee pee - let me know how you did it.

I am going to gently put the solder iron on right side and try to lift it as soon as solder start to give.  Any suggestions will be appreciated.


Re: VOM Advice?

n5ib_2
 

An interesting tale about one of those inexpensive Harbor Freight DMMs...

A few years back I was working on a GPS tracker for our high altitude balloon project. It was outdoors on a bright sunny day. I was measuring the DC supply to the GPS and noticed the voltage reading bouncing around for no apparent reason. After a few minutes of bafflement I noticed that when I leaned over to read the meter, it was in my shadow, and the reading changed. Curiosity piqued, the meter (one of the early yellow ones) was promptly disassembled for inspection.

Turns out the chip that controls the whole thing was, as in most low-cost mass-produced stuff, not encapsulated in a package, but just die bonded to the PCB with a resin overcoating. The ground plane beneath the die was etched away on the other side of the PCB. The chip was located right underneath the LCD display. Strong sunlight would filter through the display, through the translucent PCB material, and fall on the silicon substrate of the chip. Can you say "phototransistor" ?! A bit of strategically placed black tape solved the problem. I've taken apart some later versions of that DMM and see that there now is an opaque strip underneath the display.

N5IB

Re: Transmitter Mods

Jack, W8TEE
 

Last night I gave a presentation to our club about using SMD parts in projects. One of the things I discussed was the use of a decent solder station, like this one:

Inline image

which sells for $62 (eBay 381253195679). I have one and it works well. The nice thing about a hot air gun is that the kind of thing you're talking about is pretty easy since both ends of the SMD are heated at the same time. (See the hot air nozzle choices.) This one even has a small variable PS with it which sometimes is handy when breadboarding. The microscope I want to get is different than what I have. This is the one I want to get: eBay #123142757131 for about $60.

Because my club has a fairly active knot of members who enjoy building "stuff", I'm going to propose that the club purchase both items as part of our Tool Chest, which our members can sign out.


Jack, W8TEE


On Friday, June 15, 2018, 9:18:49 AM EDT, Rob Snow <rsnow@...> wrote:


Sajid,

The teepee was the hardest part for me.  My first thought was to heat one side and try to lift it, but that didn't work as the other side still held tough.  Next I wicked both ends and then tried the same thing again and got some movement.  Finally, I just applied pressure to the side and heat and slid it off the pad completely and started the tee pee fresh.  My inductor is a squat little thing so I soldered it down as a tower on one pad and then re-applied the resistor as a bridge.

My biggest concern was either a) destroying the resistor with heat, or b) flicking it off and sending it into the ether while trying to desolder.  I have a SMD resistor sampler pack and I think I read it as being a 102 (1k ohm), so I had that as a fallback and maybe made me a bit braver on my application of heat and force.


On Fri, Jun 15, 2018 at 7:24 AM, Sajid Rahum via Groups.Io <zs735@...> wrote:
Hi Rob

Doing these mods this evening.  Much appreciated Howard's parts.

For the tee pee - let me know how you did it.

I am going to gently put the solder iron on right side and try to lift it as soon as solder start to give.  Any suggestions will be appreciated.


Re: My first ubitx #ubitx

Alex KA3BQE
 

Brad, you may want to look into "CTC-50M Original Comet Window Feed-Thru Jumper" they are a bit pricy but have good reviews up on Amazon. 

Re: VOM Advice?

Vince Vielhaber
 

Back when those meters were going for $6-$8 at trade shows and ham swaps, I was buying them in quantities of 96 or more (they came in boxes of 48, that's why the 96 price break) for a few pennies over $2. Still have a bunch of 'em left, batteries are dead tho.

Vince.

On 06/15/2018 12:52 AM, Jerry Gaffke via Groups.Io wrote:
That's the same Centech brand as the red rectangular cheapies form
Harbor Freight.
Pretty much the same functionality. And I'd guess the same stuff inside.
The primary differences I see is that this ebay job has a continuity
beeper and a backlight.

Jerry



On Thu, Jun 14, 2018 at 08:11 pm, Tim Gorman wrote:

For most anything you'll do with the ubitx you don't need an expensive
desk meter.

this one:
www.ebay.com/itm/Digital-Voltmeter-Ammeter-Ohmmeter-Multimeter-Volt-AC-DC-Tester-Meter-US-Seller/271496690158?hash=item3f3676b9ee:g:qgUAAOSwHnFVkYPk

is representative of one that has lots of functions. It's a lot like
the one I use much of the time. PLEASE don't hook the test leads up the
way it is shown, it won't work!

There is a huge gap in its current measuring scales, from 200ma to
10amp in one big jump, but that will probably get you by.

tim ab0wr

Re: How to order a Raduino

Geoff Theasby <geofftheasby@...>
 

Hi Mike,

I would like to order an assembled  Raduino UMax. First, can I check whether it is preprogrammed so I can plug in and go? As Nano is extra, does this mean it isn't?

I have the LCD.

73,
Geoff , G8BMI

Re: Transmitter Mods

Howard Fidel
 

Sajid:
Solder the resistor standing up on one pad, and the inductor on the other. Put a piece of wire wrap wire across between the top pads. It is easier then a Tee PEE.

Howard



On 6/15/2018 8:24 AM, Sajid Rahum via Groups.Io wrote:
Hi Rob

Doing these mods this evening.  Much appreciated Howard's parts.

For the tee pee - let me know how you did it.

I am going to gently put the solder iron on right side and try to lift it as soon as solder start to give.  Any suggestions will be appreciated.


Re: VOM Advice?

 

I have heard good things about this MM from several different sources. I don't think you can beat it for quality/features VS price.

https://www.ebay.com/itm/ANENG-AN8008-True-RMS-Wave-Output-Digital-Multimeter-9999-Counts-Backlight-AC-DC/222719150587?hash=item33db1889fb:m:mSCw_nrSk9gqavl1qMGdf8Q

Joel
N6ALT

Re: VOM Advice?

Gwen Patton
 

I have a couple of older Radio Shack VOMs around here, mostly for field use (from back when I did computer field service), but I lucked out for my bench VOM. I got a Fluke 27/FM, the military model, on Ebay. If not for a song, it was at least for a couple of choruses and a jingle -- a small percentage of the original price of the civilian model. This one was of a large batch that had been purchased for the military and never deployed, but instead had been warehoused. They maintained them well, calibrating them before they sold them off. I paid about $80 plus a little shipping. It has served me more than adequately, and is a True RMS meter with a HUGE display and more features than I'll ever use. I love the thing to pieces.

Keep an eye out for sales of such on Ebay. If you spot such a deal, pounce on it. You won't regret having such a wonderful device on your bench.

Gwen NG3P

Re: Transmitter Mods

Rob Snow
 

Sajid,

Just to lower your anxiety I'm going to post a pic of my mods so you can see how badly it can be done and still work.  May the soldering gods have mercy on my soul for posting this with my globs of dull solder!

This was done with a flat tipped soldering iron + wick, some vodka for my shakes (I'm old) and +3.0 eye glasses.  Note that the cap on top of R87 looks like it's not connected with solder, but if you zoom in you'll see it is.  I decided not to go back in with wick to clean it up as nobody will ever see it (until now). 

If I can do it, you can.   Start with R87 and R88, they are much easier as all you need to do is hold the cap down on top (I used the pointy end of my tweezers to stab it down) and dab some solder on one of the ends to get it to hold.

73 Rob AG5OV (prepared for the wrath of the soldering gods)

Re: Transmitter Mods

Art Olson
 

Howard

Would like to request the parts for the mod. What do you need from me

Art - N2AJO 


On Jun 15, 2018, at 10:27 AM, Rob Snow <rsnow@...> wrote:

Sajid,

Just to lower your anxiety I'm going to post a pic of my mods so you can see how badly it can be done and still work.  May the soldering gods have mercy on my soul for posting this with my globs of dull solder!

This was done with a flat tipped soldering iron + wick, some vodka for my shakes (I'm old) and +3.0 eye glasses.  Note that the cap on top of R87 looks like it's not connected with solder, but if you zoom in you'll see it is.  I decided not to go back in with wick to clean it up as nobody will ever see it (until now). 

If I can do it, you can.   Start with R87 and R88, they are much easier as all you need to do is hold the cap down on top (I used the pointy end of my tweezers to stab it down) and dab some solder on one of the ends to get it to hold.

73 Rob AG5OV (prepared for the wrath of the soldering gods)

<2018_06_13 19.15.00.jpg>

Re: How hot is too hot? #ubitx

Allen Merrell
 

Nextion  recommends using at least 500 ma supply for their display. 
--
Allen  Merrell

Re: Can't get my uBitX to transmit CW on the Dial frequency

Tim Gorman
 

Jerry,

On Thu, 14 Jun 2018 20:57:48 -0700
"Jerry Gaffke via Groups.Io" <jgaffke=yahoo.com@groups.io> wrote:

I'm not sure what you mean about shifting the BFO.
The BFO has nothing to do with transmit.
On receive, it can remain exactly where it was for SSB operation.
The original message says: "The uBITX is on CWU has a 700 Hz sidetone
set (ie offset) then the dial on the uBITX needs to be at 7.029.300
Mhz  so that it is receiving a the Flex with a 700hz audio tone."

If you are working CW at 7030 then why should you have to set the
receive frequency to 7.029.300? That just means you need to know
whether you are in CWL or CWU and do math in your head to know what
frequency you are actually listening to!

Why not just shift the BFO so the receive frequency can remain showing
7030 and you still get your 700hz tone?



And no idea what all the other software releases out there are doing.
Mine is rigged as follows

On transmit the dial shows the frequency of the CW carrier (of
course).

On receive (if RIT is not enabled) it still shows the same operating
frequency in the LCD. However, the VFO is tuned up in frequency by
however many hertz the cw sidetone is set up to be if operating in
LowerSideBand mode, and down in frequency by that many hertz if
UpperSideBand mode.
This is *exactly* what I am saying. You are doing it with the VFO. You
can do it with the BFO as well! It's why my homemade receivers always
had two BFO frequencies. It was easier to shift the BFO oscillator with
a switched-in capacitor than to try and shift the VFO frequency in an
analog vfo!

Apparently the software Michael is using utilizes neither of these
methods.

tim ab0wr

Re: SI5351 quadrature VFO

Jerry Gaffke
 

Hans,

Code for the uBitx has been using my si5351bx routines since day one. 
Allards Bitx40 code also uses these routines starting summer of 2017.
The uBitx routines are also 32 bit fixed point math. 
Precision was within about 10ppb as I recall.
So the uBitx tuning is correct within about 30e6/10e9 =  0.3 Hz when operating at 30mhz, is proportionally better as you go down in frequency,
the 25mhz reference oscillator will vary by far more than that with slight variations in temperature.
Of course, the calibration must be done correctly per post 35235 to approach this kind of accuracy.
Judging from all the posts to the forum about having to take multiple runs to calibrate vfo and bfo and clk1, 
most uBitx software releases out there have not yet gotten this right. 

Primary execution time constraint is shoveling all those i2c bits out to the si5351 at 100khz,
could be bumped up to 400khz if that's of concern.

The uBitx shuts down clk0 and clk1 when transmitting CW, this avoids any possibility of 
those mixer products getting out to the antenna.  A slight speed-up of maybe 10 milliseconds could be had
by only touching the clock-enable bits in si5351 register 3 to turn these off and on rather than 
loading all those msynth registers each time.  Doesn't really matter unless attempting 
full break-in for high speed CW with solid state TR switching.

Jerry, KE7ER



On Thu, Jun 14, 2018 at 10:27 pm, Hans Summers wrote:
Use of floating point arithmetic greatly increases the code size. And execution time - but generally I have found the execution time is not usually a constraint, neither is RAM or EEPROM... the biggest constraint I run into is the Flash program memory size. 64-bit arithmetic increases the code size even worse than floating point. Accordingly I use only 32-bit unsigned integer arithmetic in my Si5351A configuration routines in my firmware. It is possible to do all the calculations in 32-bit arithmetic without losing any precision (Floating point loses precision, 64-bit increases the code size too much). The result is compact code and accurate.