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Re: Transmit indicator light.

 

I bet that someone? could come up with a circuit of a diode, capacitor and resistor to feed into the same analog pin as the s-meter in the modified software so you could see about how much power was going out.

Seems simple enough to me, but I do not have the coding skills to do that.


On Mon, Jun 18, 2018 at 2:10 PM, Arv Evans <arvid.evans@...> wrote:
Roy WA0YMH

Probably could use a diode rectifier and filter cap at the toroid location and run
DC to the front panel LED.? I have never tried that because radiated RF inside
the chassis has never been a problem.

Using a rectifier and filter cap could also let you measure RF current on an ADC
input of the Arduino.? Interesting thought that if you measure RF current and RF
voltage at the antenna jack it might be possible to calculate antenna impedance.

Arv? K7HKL
_._


On Mon, Jun 18, 2018 at 11:48 AM Roy Appleton <twelveoclockhigh@...> wrote:
The following is a question not a statement.

Typically the ant lead is at the back of a radio case and the LED indicator would be on the front panel. Wouldn't running the wires feeding the LED that distance cause a potential of rf radiation into the radio?

Roy
WA0YMH

On Mon, Jun 18, 2018, 10:47 AM Arv Evans <arvid.evans@...> wrote:

_._

On Mon, Jun 18, 2018 at 8:07 AM Praba Karan <vu3dxr@...> wrote:
Circuit diagram to enable this idea?..

On Sat, Apr 21, 2018, 3:51 AM Don, ND6T via Groups.Io <nd6t_6=[email protected]> wrote:
In my opinion, the very best LED transmit indicator was the one that Derry Spittle (VE7QK [SK]) used in his Epiphyte QRP SSB series. That was just a 470 ohm quarter watt resistor through a small toroid and attached to a panel-mounted LED at each leg. The lead to the antenna passed through next to that resistor. That was it! When RF went to the antenna, it lit. You could easily tell if you were speaking loudly enough into the microphone, etc. Fast response, little panel space, and EASY. 73, Don
Re: Transmit indicator light.

 

Roy WA0YMH

Probably could use a diode rectifier and filter cap at the toroid location and run
DC to the front panel LED.? I have never tried that because radiated RF inside
the chassis has never been a problem.

Using a rectifier and filter cap could also let you measure RF current on an ADC
input of the Arduino.? Interesting thought that if you measure RF current and RF
voltage at the antenna jack it might be possible to calculate antenna impedance.

Arv? K7HKL
_._


On Mon, Jun 18, 2018 at 11:48 AM Roy Appleton <twelveoclockhigh@...> wrote:
The following is a question not a statement.

Typically the ant lead is at the back of a radio case and the LED indicator would be on the front panel. Wouldn't running the wires feeding the LED that distance cause a potential of rf radiation into the radio?

Roy
WA0YMH

On Mon, Jun 18, 2018, 10:47 AM Arv Evans <arvid.evans@...> wrote:

_._

On Mon, Jun 18, 2018 at 8:07 AM Praba Karan <vu3dxr@...> wrote:
Circuit diagram to enable this idea?..

On Sat, Apr 21, 2018, 3:51 AM Don, ND6T via Groups.Io <nd6t_6=[email protected]> wrote:
In my opinion, the very best LED transmit indicator was the one that Derry Spittle (VE7QK [SK]) used in his Epiphyte QRP SSB series. That was just a 470 ohm quarter watt resistor through a small toroid and attached to a panel-mounted LED at each leg. The lead to the antenna passed through next to that resistor. That was it! When RF went to the antenna, it lit. You could easily tell if you were speaking loudly enough into the microphone, etc. Fast response, little panel space, and EASY. 73, Don
Re: VOM Advice?

Mark M
 

Thanks for all the input. I didn't expect to get so many replies! Looks like there are lots of alternatives out there. Now to chase them down & decide which way to go.

Thanks & 73...? ? ?Mark? ? AA7TA
Re: Transmit indicator light.

 

The following is a question not a statement.

Typically the ant lead is at the back of a radio case and the LED indicator would be on the front panel. Wouldn't running the wires feeding the LED that distance cause a potential of rf radiation into the radio?

Roy
WA0YMH

On Mon, Jun 18, 2018, 10:47 AM Arv Evans <arvid.evans@...> wrote:

_._

On Mon, Jun 18, 2018 at 8:07 AM Praba Karan <vu3dxr@...> wrote:
Circuit diagram to enable this idea?..

On Sat, Apr 21, 2018, 3:51 AM Don, ND6T via Groups.Io <nd6t_6=[email protected]> wrote:
In my opinion, the very best LED transmit indicator was the one that Derry Spittle (VE7QK [SK]) used in his Epiphyte QRP SSB series. That was just a 470 ohm quarter watt resistor through a small toroid and attached to a panel-mounted LED at each leg. The lead to the antenna passed through next to that resistor. That was it! When RF went to the antenna, it lit. You could easily tell if you were speaking loudly enough into the microphone, etc. Fast response, little panel space, and EASY. 73, Don
Re: Damage to uBITX from nearby QRO transmitter (no power out on TX) ? #ubitx

 

Jerry, thanks for the heads up on msg #37380. Somehow I missed that discussion late last year.?

I don't recall anyone postings about problems with Q90 on the uBITX and given the number of
"blown" Q13s in the BITX40, either people have become more cautious (unlikely), or as
Farhan suggests, the first diode ring mixer is offering enough protection.

As they say, "if it ain't broke, don't fix it" !

Cheers

Michael VE3WMB?
Re: Low RX Audio #ubitx

 

Have a usb oscilloscope with built in dds. Will check today. Thanks for the idea.
Re: Damage to uBITX from nearby QRO transmitter (no power out on TX) ? #ubitx

 

The incandescent lamp is good because resistance of the filament increases by 10x as it heats up.
Here's an old thread on that:? ?/g/BITX20/message/31352

The back to back diodes on the uBitx may not be a good idea however,
as they could introduce spurs as stated in my previous post.

Jerry, KE7ER


On Mon, Jun 18, 2018 at 09:28 am, iz oos wrote:

You can put a very small lamp in series before the back to back diodes, to increase protection. Consider however that diodes would add some overload.

?
Re: Damage to uBITX from nearby QRO transmitter (no power out on TX) ? #ubitx

 

A fix was earlier suggested for this. let us check

Regards
MVS Sarma
?

On Mon, Jun 18, 2018 at 10:03 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
Very few reports here of Q90 on the uBitx getting blown.
Q13 was getting fried quite often on the Bitx40.

Farhan figures that front end protection diodes will create lots of extra spurs,
and that the first diode ring mixer offers adequate protection.
? ??/g/BITX20/message/37380

Worth experimenting with.?

Jerry




On Mon, Jun 18, 2018 at 07:05 am, Michael Babineau wrote:
Has anyone reported damage to their uBITX (little or no power out on TX) caused by previously keying a QRO rig nearby ??

This was a common problem with the BITX40 as high voltages present on the antenna input during RX,
caused by transmitting with a QRO rig close by, was frying Q13.

The?solution was to put a pair of parallel 1N4148 diodes to ground (each with opposite orientation) at relay K1 PIN12.
This is well documented in message # 25062.?

Looking at the corresponding part of the uBITX (v3) schematic it looks virtually identical to the BITX40 except the transistor in question is labelled Q90.
It seems that there is the potential for the same issue as with the BITX40 to occur (unless I am missing something).?

The solution appears to be the same, a pair of parallel diodes (opposite orientation) from relay K1 PIN 12 to ground.?

Cheers

Michael VE3WMB?
Re: Damage to uBITX from nearby QRO transmitter (no power out on TX) ? #ubitx

 

Very few reports here of Q90 on the uBitx getting blown.
Q13 was getting fried quite often on the Bitx40.

Farhan figures that front end protection diodes will create lots of extra spurs,
and that the first diode ring mixer offers adequate protection.
? ??/g/BITX20/message/37380

Worth experimenting with.?

Jerry




On Mon, Jun 18, 2018 at 07:05 am, Michael Babineau wrote:
Has anyone reported damage to their uBITX (little or no power out on TX) caused by previously keying a QRO rig nearby ??

This was a common problem with the BITX40 as high voltages present on the antenna input during RX,
caused by transmitting with a QRO rig close by, was frying Q13.

The?solution was to put a pair of parallel 1N4148 diodes to ground (each with opposite orientation) at relay K1 PIN12.
This is well documented in message # 25062.?

Looking at the corresponding part of the uBITX (v3) schematic it looks virtually identical to the BITX40 except the transistor in question is labelled Q90.
It seems that there is the potential for the same issue as with the BITX40 to occur (unless I am missing something).?

The solution appears to be the same, a pair of parallel diodes (opposite orientation) from relay K1 PIN 12 to ground.?

Cheers

Michael VE3WMB?
Re: Damage to uBITX from nearby QRO transmitter (no power out on TX) ? #ubitx

 

You can put a very small lamp in series before the back to back diodes, to increase protection. Consider however that diodes would add some overload.


Il 18/giu/2018 16:05, "Michael Babineau" <mbabineau.ve3wmb@...> ha scritto:
Has anyone reported damage to their uBITX (little or no power out on TX) caused by previously keying a QRO rig nearby ??

This was a common problem with the BITX40 as high voltages present on the antenna input during RX,
caused by transmitting with a QRO rig close by, was frying Q13.

The?solution was to put a pair of parallel 1N4148 diodes to ground (each with opposite orientation) at relay K1 PIN12.
This is well documented in message # 25062.?

Looking at the corresponding part of the uBITX (v3) schematic it looks virtually identical to the BITX40 except the transistor in question is labelled Q90.
It seems that there is the potential for the same issue as with the BITX40 to occur (unless I am missing something).?

The solution appears to be the same, a pair of parallel diodes (opposite orientation) from relay K1 PIN 12 to ground.?

Cheers

Michael VE3WMB?
Re: BITX QSO Afternoon/Evening, Sunday, June 17, 3PM & 7PM Local Time, 7277 kHz in North America, 7177 kHz elsewhere.

Ken Peck
 

I got on late, about 7:15 Eastern.? I tuned around 7277 a bit above and below and didn't hear anyone.? I tried calling CQ BITX a few times, but heard nothing.
Re: Help with AGC kit wiring

 

Don is out of town for the 4th and he can provide nice looking drawings. I probably need to put "snaps" on my board as often as I've taken it out of the unit.

However the picture associated with?? gives you a rough idea (but uses 2 pins and is less mechanically secure).?
This is for the Ver 3 uBITX board. I understand there are some differences between it and the Ver 4 uBITX board but i don't have one to check. Hopefully this will help clear up the questions:

1) remove a 0.2" section of the trace where you want to install the AGC
2) scrape the solder mask off the trace ends and prepare them for soldering by tinning them
3) drill a header pin size hole in the middle of the 0.2" section you removed. It will go through the ground plane on the other
? ? side of the board.
4) scrape the solder mask off around the hole on the ground side. That is where the middle header pin will be soldered.
? ? Requires lots of heat because the hole will haver no thermals.?
5) take a 3 pin section of male header and bend the short leads out at right angles (in the same plane as the rest of the
? ? header pins to match the tinned trace ends when?you insert the middle pin in the hole you drilled.
6) solder the 3 pin header in place ....you can add super glue if you want but not necessary.
7) solder a 3 pin section of female header to the AGC board. Note the pins are labeled "IN" (to K3 pin 14) and "OUT"
? ? (to K1 pin 12).The connector can be mounted parallel to the AGC board (bend the pins 90 degrees) which?results in
? ? the AGC board being plugged perpendicular to the uBITX board or at right angles which results in the AGC
? ? board being parallel to the uBITX board. Make sure there is no interference (shouldn't be).
8) the rest of the wiring can be attached to the top or bottom of the AGC board .....your choice.
9) you can use a RF Gain pot or jumper that function out (jumper location is labeled and provided) ....your choice
10) you can use an "AGC hold time" jumper (provided) manually or add an AGC "Off, Fast, Slow" switch and wire it over
? ? ?to the?double row header.....your choice. The higher the resistance, the longer the AGC Hold Time.
11) you can add a S-meter connection as explained by Don.....your choice.

73 Kees K5BCQ
??
Re: Transmit indicator light.

 


_._


On Mon, Jun 18, 2018 at 8:07 AM Praba Karan <vu3dxr@...> wrote:
Circuit diagram to enable this idea?..

On Sat, Apr 21, 2018, 3:51 AM Don, ND6T via Groups.Io <nd6t_6=[email protected]> wrote:
In my opinion, the very best LED transmit indicator was the one that Derry Spittle (VE7QK [SK]) used in his Epiphyte QRP SSB series. That was just a 470 ohm quarter watt resistor through a small toroid and attached to a panel-mounted LED at each leg. The lead to the antenna passed through next to that resistor. That was it! When RF went to the antenna, it lit. You could easily tell if you were speaking loudly enough into the microphone, etc. Fast response, little panel space, and EASY. 73, Don
Nextion Display vs 1602 LCD - Current Consumption #ubitx

 

As it appears that the Nextion Display will be getting its +5V from the L7805CV regulator on the Raduino board, I started wondering
if this regulator is up to the task (it is rated at 1.5 A) and if so whether or not this might mean that adding a heatsink to the regulator
might now be a must (mine already runs pretty hot).?

First I took a peek at the datasheet for the existing 1602 Display. The VISHAY datasheet that I had previously downloaded shows that?
the Supply current (IDD) is only 3mA but it also lists LED forward current (IF) Array: 260mA Edge: 40mA (these are the Max values).
So I am assuming that this means that the worst case current draw for the existing uBITX display is 3mA + 260 mA + 40mA which would be 303 mA ??

If this assumption is correct then the average current would be around 152 mA for the existing 16x2 Display based on average numbers (1.2mA + 130mA + 20 mA).?

Looking at the specs for the Nextion 2.8 inch display () it claims that for a VCC of 5V and a Brightness of 100%? the?
typical current draw is 65mA !? This seems too good to be true.?

Unless I am missing something, this would mean using the Nextion would provide about 82mA current savings over the existing LCD display.??

Michael VE3WMB?
Re: uBitx V4 linearity mod in final audio amplifier #ubitx

 

One correction to prior posts...the diode voltage is there to match the B-E junction offset,
not to match the B-C drop.? Farhan was careful to use silicon transistors and silicon diodes
in order to make the drop very close between diode and transistor.?
Over the past 20 or so years there have been many homebrewed ham rigs that use this
configuration and do not use negative feedback to improve linearity.? That said, there is no
reason that you cannot add a resistance (100K to 150K) between output and input to to add
this feature.? This will slightly decrease the audio power out but will probably not be noticeable
if using headphones.?

Arv
_._


On Mon, Jun 18, 2018 at 4:33 AM Weddig, Henning-Christof <Henning-Christof.Weddig@...> wrote:
Mike and all UBITX enthusiasts,
when In looked on the schematic of the new audio amp my first thougt
was: why is there no feedback from the output to the input?
Please have a look on the very old schenatics of "old" and discrete
audio amps and even tube amps!!!
In all circuitries a feedback is installed to cancel the nonlinearities
of the active elements.

Henning Weddig
DK5LV

Am 17.06.2018 um 23:23 schrieb Mike:
> I believe there is an nonlinearity problem on some of the newer V4 uBitx
> radios (the one with transistors in the final audio amp). Two of my
> radios had this problem.
> The problem is that the two diodes in the final amp doesn't make a
> voltage drop that is larger than the drop over the BJT B-C junction
> drops, so there will be a crossover distortion problem.
>
> I did a mod: cut the trace between the diodes. Soldere in a 500 ohm pot
> paralelled with the a 125 ohm resistor. I adjusted the pot from a low
> value and increased the resistance until the nonlinearity disappeared by
> listening to a moderately strong cw signal. I checked the lower
> transistor so it didnt become too warn from the quiescent current.
>
> 73s
>



Re: Domino, Thor, Pi

 

Depends on your definition of handheld.? There are plenty of guides available to run fldigi on a pi.? The radio, battery, pi, and ancillary cables and connections would be a handful for all but Fezzik (or any other giant) to hold in hand, but I don't see why you couldn't put all of that in anything from a backpack to a wheelbarrow and use a phone or tablet to VNC into the pi.? This is assuming you have an antenna figured out.? You need some space between the BITX and pi to keep RF from killing the pi's wifi but not much.? I have my ?BITX in an unshielded plastic case less than a foot away from a Pi3 that I can keep a constant wifi VNC session open to.
--

Re: Low RX Audio #ubitx

 

If in doubt whether it is fine or not you might think to build a small signal generator that is able to generate just an above noise level S3 and and a good S9 signal. I made the using the manual and assembled it on copper board. I find it very useful to check the sensitivity of any receiver. You can add crystals or use the same crystal at the armonics (eg.? a 14mhz crystal may be used for 28mhz albeit is something like 10db attenuated).


Il 18/giu/2018 16:32, <3voltios@...> ha scritto:
It is just a dipole with 300ohm line. Also use a CHA 250 b.?

Re: Domino, Thor, Pi

 

I don't use Domino or Thor.? I do use PSK31 on a Rpi-3B and I see no reason why it would
not work with uBitx.? Hand held however is unlikely as you need a fair amount?of battery
for the radio, Pi and display.? That and a full size antenna at height.

Even then coast to coast is an iffy thing.? For that fact at full gallon input it can be very iffy.

So far no one has integrated the two (PI and radio) for other than SDR.

Allison
Re: Anyone ever use one of these to build a Raduino clone?

 

Yes.? I did that with a nano and 2lin display to modify and test code without messing
with the uBitx until I was happy.? It was an easy wireup and while its not as pretty/compact
it works just fine.

Allison
Domino, Thor, Pi

 

Meanwhile, over on the Zed, KE0EYJ asks, "I was wondering if there is any kind of 5w HF radio (BITX?), combined with a Rasberry Pi (or something similar) running Fldigi (or similar) as one unit, that fits in the hand, yet can transmit digital modes (not like DMR -- I want intercontinental chat)? My idea is... what if we had an inexpensive HF-based radio for text communication using Domino EX or Thor -- which automatically transmitted/received on a few set frequencies, or a swath within the digital band, so that all users of that handheld radio model could easily connect?"

It seems that someone is probably working on integrating a Pi running digital with the ?B, as a standalone without a PC?

Thanks!
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