Date   
Re: Full QSK for a uBITX

kh6sky
 

Take a look at W2AEWs video on PIN diode switching for a good intro to the subject.  Using the simple test setup in this video you could check the suitability of the 1n4007s for this purpose.  Interesting that the turn on characteristic of the PIN diodes is so strongly affected by frequency.

https://www.youtube.com/watch?v=XpYsCM_Wf50

Jim KH6SKY

Re: Full QSK for a uBITX

Jerry Gaffke
 

Thanks for finding that, seems right.
I think D3 and D4 are drawn backwards.


On Wed, Aug 7, 2019 at 08:20 PM, Vince Vielhaber wrote:
According to the voltage chart on the next page, that junction is going to have a large negative voltage on it. That would stop the transmit from going to the receiver.

Vince.
Hide quoted text

 

On 08/07/2019 07:35 PM, Jerry Gaffke via Groups.Io wrote:
Here's a manual for the Argosy, T/R switching (and SWR metering) is on
page 51:

http://www.tentec.com/wp-content/uploads/2016/05/Argosy_II_Model_525_Manualf933.pdf
;;; D1,D2 look to me like they would be forward biased during transmit,
which would not work at all.



 

Re: Full QSK for a uBITX

Vince Vielhaber
 

According to the voltage chart on the next page, that junction is going to have a large negative voltage on it. That would stop the transmit from going to the receiver.

Vince.

On 08/07/2019 07:35 PM, Jerry Gaffke via Groups.Io wrote:
Here's a manual for the Argosy, T/R switching (and SWR metering) is on
page 51:

http://www.tentec.com/wp-content/uploads/2016/05/Argosy_II_Model_525_Manualf933.pdf
The full transmit RF waveform goes through C1, diode D4 ensures the
bottom of that
waveform is at DC ground, diode D3 then rectifies it to create a DC
voltage across C2 that
is equal to the peak-to-peak voltage of the transmitted RF. The notes
then say that this
relatively high DC voltage available during transmit is used to reverse
bias diodes D1 and D2
such that no transmit signal goes through them to the RCV connector
(which then goes into
the receiver front end).

I'm still staring at it, almost have it figured out.
But D1,D2 look to me like they would be forward biased during transmit,
which would not work at all.

Note that the PIN diodes at D1,D2 are called out as 1n4007's.
And that this transceiver works up through 30mhz.

Another thing to note, the final remains connected to the antenna during
receive,
shunting some of the receive energy to ground.
Some of the other T/R switches use additional PIN diodes to isolate the
final
from the antenna during receive.

Jerry, KE7ER


On Wed, Aug 7, 2019 at 01:37 PM, John Seboldt K0JD wrote:

This is quite interesting, with a nice sophisticated full-tilt
switch. Interestingly, the Ten Tec Argosy (50W) derives the high
voltage back bias from the RF itself with some silicon diodes and
filter capacitors, so providing a full high-voltage power supply is
a bit of an overkill.

John K0JD

Re: Another uBITX v5 FT8 success story #ft8 #v5 #ubitx

Don - KM4UDX
 

Arvo -- hahah.  

Q: do you have to worry about the fan current if you hack into the TX 12v line, namely at pin 3 on U2?

Don
km4udx

Re: Voltage for finals

Don - KM4UDX
 

John -- do it the reverse.  Start with an old 15-20v laptop power supply. Put a 2a fuse and drive the finals direct from the laptop brick voltage.  Use the buck converter to generate 12v for the board from whatever the laptop brick squrts out.  I added a simple LC ripple filter (used in RC drones) to the 12v output, but it made no detectable difference to anything I could observe. With 17v, I get ~28 watts on 80m, and the normal 3 watts on 10m.  Good enough for all the digital modes, and yes, marginal for SSB DX, says me. Others disagree. 

Increase the size of the heat sinks, or go active if you up the final voltage. Not that the finalls need it in normal operation, but to cover a likely bone-head move by the operator. Don't ask me how I know this. 

In anycase, it is (largley) over driving which generates spurs and uggly bits.  Not the PSU ripple.

Don
km4udx

Re: Voltage for finals

 

My plan is to use them only on the battery circuit, and possibly to power something that needs a stable 5v supply with proper filtering.

Matthew N8OHU


On August 7, 2019 1:31:55 PM EDT, John Faivre <wa9sgd@...> wrote:
Has anyone tried using a buck boost module to raise the finals voltage supply? I’m worried about the noise from the supply ending up causing spurs on my output.

How high have you successfully run the final voltage, and with what heat sink setup.

thanks for you help 

--
Sent from my Android device with K-9 Mail. Please excuse my brevity.

Re: Transmit Trouble

harryoliver196410@...
 

Thanks Curt,
That makes sense - yes I have the resistor there but I haven't specifically checked the menu settings so I shall definitely do that. It's 1:30am here so I think I should probably leave it till the morning but I will let you know how I get on. 
Thanks again. 
Harry

Re: Transmit Trouble

Curt
 

harry

you are doing well with all that advancing, and i sense you are close with the ubitx. did you install that 4.7k resistor that is needed for transmit?  I call there is also a menu setting to tell it to expect a manual key and not a paddle.  with the proper menu setting and that resistor a short circuit across the key should place it into cw transmit.  note you need to speak or whistle into the microphone to get any ssb transmit output.  check things patiently and I expect you will solve it.  maybe we can qso via ubitx this fall. 

73 Curt

Re: Full QSK for a uBITX

Jerry Gaffke
 

Here's a manual for the Argosy, T/R switching (and SWR metering) is on page 51:
    http://www.tentec.com/wp-content/uploads/2016/05/Argosy_II_Model_525_Manualf933.pdf
The full transmit RF waveform goes through C1, diode D4 ensures the bottom of that
waveform is at DC ground, diode D3 then rectifies it to create a DC voltage across C2 that
is equal to the peak-to-peak voltage of the transmitted RF.  The notes then say that this
relatively high DC voltage available during transmit is used to reverse bias diodes D1 and D2
such that  no transmit signal goes through them to the RCV connector (which then goes into
the receiver front end).

I'm still staring at it, almost have it figured out.
But D1,D2 look to me like they would be forward biased during transmit,
which would not work at all.

Note that the PIN diodes at D1,D2 are called out as 1n4007's.
And that this transceiver works up through 30mhz.

Another thing to note, the final remains connected to the antenna during receive,
shunting some of the receive energy to ground.
Some of the other T/R switches use additional PIN diodes to isolate the final
from the antenna during receive.

Jerry, KE7ER


On Wed, Aug 7, 2019 at 01:37 PM, John Seboldt K0JD wrote:

This is quite interesting, with a nice sophisticated full-tilt switch. Interestingly, the Ten Tec Argosy (50W) derives the high voltage back bias from the RF itself with some silicon diodes and filter capacitors, so providing a full high-voltage power supply is a bit of an overkill.

John K0JD

Re: Full QSK for a uBITX

John Seboldt K0JD
 

This is quite interesting, with a nice sophisticated full-tilt switch. Interestingly, the Ten Tec Argosy (50W) derives the high voltage back bias from the RF itself with some silicon diodes and filter capacitors, so providing a full high-voltage power supply is a bit of an overkill.

John K0JD

On 8/6/2019 15:01, Tom, wb6b wrote:
On Tue, Aug 6, 2019 at 08:26 AM, Jerry Gaffke wrote:
including "ElectronicAntenna Switching" by Wes Hayward 
I was able to find the Wes Hayward article on-line. 
https://archive.org/stream/QEX19812016/QEX%201995/QEX%201995-05#page/n3/mode/2up

Tom, wb6b

Re: Voltage for finals

Evan Hand
 

Did not use it for the finals, though did try one for the full system.  Generated some noise, so you do have less sensitivity compared to the normal QRN.  If only used on the finals, may not be an issue.

Since there are 30+ amp switching supplies for other rigs, I would think that if you found the right unit the noise would not be significant.  It is just that the units that I tried did generate noise.  Might also be able to filter out the noise with active or passive filters.

My 2 cents
73
Evan
AC9TU

Re: Series Diode in Power Supply Line #ubitx

Jerry Gaffke
 

An LM2940T-12 is similar to an LM7812 except that it is low dropout, offers polarity protection, and is not quite so prehistoric.
I'd recommend a 3A fuse between power supply and the rig, use an LM2940T-12 inside the rig to power the main board.
Have the power supply with 3A fuse drive the IRF510's directly to avoid overloading the LM2940T-12.
If the supply is reversed, the intrinsic diodes in the IRF510 will conduct and blow the fuse.
With that arrangement, you could supply 20vdc to the rig if you want more power, the main board will still only get 12v.

For a really cheap solution on a high volume project where we can assume the power supply voltage
does not exceed the maximum that the rig can handle, replace the LM2940T-12 with a small shottky diode.
Offers polarity protection, and a short on the board will blow the diode.

A search for "reverse polarity" in this forum will find long discussions with dozens of ways to do this.
One of those things that everybody seems to have an opinion on.
Including me.

Jerry, KE7ER


On Wed, Aug 7, 2019 at 08:21 AM, Ashhar Farhan wrote:
I would second that. A voltage regulator is best. However, the generic ones like 7812 will need at least 15v (3v more than the output) as their inpit voltage. A small 1uf and a couple of 0.1u caps across the output makes for a nice, low noise supply.
 

Voltage for finals

John Faivre
 

Has anyone tried using a buck boost module to raise the finals voltage supply? I’m worried about the noise from the supply ending up causing spurs on my output.

How high have you successfully run the final voltage, and with what heat sink setup.

thanks for you help 
--
John Faivre WA9SGD

Re: Series Diode in Power Supply Line #ubitx

Ashhar Farhan
 

I would second that. A voltage regulator is best. However, the generic ones like 7812 will need at least 15v (3v more than the output) as their inpit voltage. A small 1uf and a couple of 0.1u caps across the output makes for a nice, low noise supply.

- f

On Wed 7 Aug, 2019, 8:44 PM Evan Hand, <elhandjr@...> wrote:
Yes, I agree for the reverse polarity power protection.  Still need a way to drop the voltage to the board separated from the finals.  The most accurate solution is a voltage regulator with the relay for the reverse protection.

The Diodes and fuses do work, as I did connect an old HP power brick that had the center pin negative, and sleeve positive.  Popped the fuse nicely.

FWIW
73
Evan
AC9TU

Re: Series Diode in Power Supply Line #ubitx

Evan Hand
 

Yes, I agree for the reverse polarity power protection.  Still need a way to drop the voltage to the board separated from the finals.  The most accurate solution is a voltage regulator with the relay for the reverse protection.

The Diodes and fuses do work, as I did connect an old HP power brick that had the center pin negative, and sleeve positive.  Popped the fuse nicely.

FWIW
73
Evan
AC9TU

Re: Si5351 minimalist routine

Jerry Gaffke
 

This is the first time I have heard of anybody using the si5351bx routines
with a non-zero rdiv.  Good to hear that you have found a good home for it.
Give my regards to your friends in Cuba.

Jerry


On Wed, Aug 7, 2019 at 07:06 AM, CO6EGM wrote:
Thanks Jerry for the example... I was studying your routine, but on the CEC firmware it was rdiv=0 at all times... I’m working on a new synthesizer for my RFT SEG15D, but also I’m wanna help a lot of friends on Cuba that have the same rig out of service due to PLL issues... over there is so difficult to fix it. I know a $15 part is considered a luxury part on my country, but it’s better than get a lot of headaches with the original PLL . 
I also need to say thanks to Ashar Farhan for the Raduino and also for the bitx family... Very simple and effective circuits..,

Re: Series Diode in Power Supply Line #ubitx

MadRadioModder
 

This is better.  No shorting diodes to replace, etc.

 

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of MVS Sarma
Sent: Tuesday, August 6, 2019 10:49 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Series Diode in Power Supply Line #ubitx

 

There would be power loss as we need around 3 amps.  Addex to that the 12  or 13.8 will actually suffer 2v drop even though we say that sili on dioďe drop is 0.7v 

 

The best optiòn appears to have shunt diode, that too àfter à fuse. The fuse protec ts the rig from  it getting reverse voltage eternally.

 

On Wed, 7 Aug 2019, 9:04 am Wayne Leake, <wayneleake@...> wrote:

 While the two diodes in series would be adequate, I would still prefer to keep the diode across the positive to negative line, so it will let you know by blowing the fuse.

 A bit redundant, but still a good idea.

 Hey,the diodes are cheap enough.

 I have far more than I'll be using for some good while.

 

 Oh yes, another idea is to use a full wave bridge, so you can connect either way;

  I had a printer buffer many years ago, that could have the power connected either way.


 Wayne WA2YNE

 

 


Virus-free. www.avg.com

--

…_. _._

Transmit Trouble

harryoliver196410@...
 

Hi All and hello from the UK,

Firstly I need to emphasize that I'm a Newbie at all of this - and whilst thoroughly enjoying every second of it, I'm still very naive - passed Foundation & Intermediate and am now struggling for the Full.
Anyway, built my uBitx on a board, connected to a QRP-Labs Dummy Load and all appeared good.  When I click on the PTT button it goes into Tx.  The reception from my droopy dipole is (relatively) excellent.
However, when I attempted an approximation of output power using the mic and the dummy load, the result was minuscule.  So, in an attempt to obtain a more consistent power output, I tried shorting the CW 3.5mm socket. This refuses to give me any dots or dashed and does not go into Tx mode.  
I have undertaken the checks that I can on the wiring etc and had a look at the troubleshooting guide but that was a bit beyond my current capabilities.  So as I see it, I have two problems that may well be related but to be honest I am struggling.
I would also add that my ATU is not registering any output.

Thanks
Regards
Harry

Re: Si5351 minimalist routine

CO6EGM
 

Thanks Jerry for the example... I was studying your routine, but on the CEC firmware it was rdiv=0 at all times... I’m working on a new synthesizer for my RFT SEG15D, but also I’m wanna help a lot of friends on Cuba that have the same rig out of service due to PLL issues... over there is so difficult to fix it. I know a $15 part is considered a luxury part on my country, but it’s better than get a lot of headaches with the original PLL . 
I also need to say thanks to Ashar Farhan for the Raduino and also for the bitx family... Very simple and effective circuits..,

Re: Another uBITX v5 FT8 success story #ft8 #v5 #ubitx

Arvo W0VRA
 

Speaking of heat and stupidity, I ran an entire WSPR transmission on 40m with no antenna connected.  I was thinking, "Wow, something smells hot."  It scorched the board, but the IRF510s still work today.

I did add a fan later...

http://ubitx.net/2018/06/28/a-fan-for-your-ubitx/