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Ubitx Ver 6 need PTT circuit for Linear AMP


robert pohorence
 

Hello all I did a search for the Ubitx Ver 6  PTT circuit for Linear AMP. couldn't find anything for the Ver6? Any info would be appreciated..
--
Rob N8RT


Evan Hand
 

Rob,
I have been monitoring this reflector for over 2 years and have never seen a post on adding PTT for the uBITX to trigger a linear amp.

With the above understanding, and the knowledge that I have yet to do this, my approach would be one of two ways:
1 - Tie into the PTT line of the mic
2 - Tie into the transistor driving K3 relay to drive another relay to trigger the linear PTT.

I am leaning towards the second choice.  The main reason is that there is a built-in delay from powering the transmit sections in the uBITX to turning on K3.  This is just relay delay but should be enough to keep from spiking the linear.  For either choice, you need to follow the PTT line input logic of the linear.  I have seen both grounding (shorting) and providing 5 or 12 volts to trigger operation.

Good luck, and maybe you can post how you did it.
73
Evan
AC9TU


Dean Souleles
 

Hi Evan and Rob -

Master builder N6QW, Pete Juliano has the solution...(same for V6)

http://bitxhacks.blogspot.com/2017/12/adding-external-linear-amplifier.html

(Evan - I've answered this twice myself in the last 6 months .... do you have me blocked?  :) )

Dean
KK4DAS 


Evan Hand
 

Thanks, Dean,

I guess my memory is failing as I do not remember those posts.

Again, thank you for providing the information

73
Evan
AC9TU


Dean Souleles
 

No worries - as long as the memory is not the second thing to go!

It's 4:00PM here - can't remember what I had for breakfast!.

Dean


robert pohorence
 

Hi Dean, and Evan, Dean the info you provided is for a VER 5 PTT is not applicable to the V6 model. The V6 has no wires coming off the mic connector  the V6 mic connector is soldered directly to the PC Board.

I see the PTT line in the V6 schematic  shows it going to Pin 2 of the raduino1 socket but when I check it from the  back of the connector with an ohm meter and key the mic, I cannot get the PTT ground?

I know the V6  mic jack  provides a ground connection on the Ring  not the tip. 
.

The added amp keying for the V5 info is OK . Put still hunting for the  V6 PTT Ground.

Thanks to both for info.
-- 
Rob N8RT


Evan Hand
 

Rob,
I am not sure what you mean by the PTT Ground.  The PTT circuit is the same for all of the versions, the only difference is that the 3.5mm jack is soldered directly to the v6 board.  The PTT signal line, the one that is grounded to turn on the transmitter, is the same on both.  That is the sleeve of the 3.5mm plug is ground and the PTT signal is the ring.  To turn on the TX/RX relay you ground the ring to the sleeve. 

I see your choices as either building an external box to parallel the PTT grounding from the mic like that shown in the article that Rob provided, or you will need to tap into any of a number of points directly on the mainboard.  You could just parallel the linear PTT relay coil that you would add across either K1 or K3 coil on the mainboard.  That would reduce the parts required slightly as the protection diodes are already there.  Then connect the contact that would be the PTT signal to the linear.

Do you know the type of signal that the linear requires?  Is it ground or a dc voltage?  This will impact the type of interface you will need to provide.  The one in the article assumes that a grounded PTT line to the amp will put it into transmit mode.  The other possibility is a DC voltage to turn on a relay, or in one case a bias voltage, internal to the amp.

I will state again that these are just ideas on my part.  I have not done them as of yet.  I am still working on the cheap Chinese linear amp kit that I bought and built.  It has harmonic issues on it's own that I need to address.

73
Evan
AC9TU


Bob Lunsford
 

On Saturday, August 29, 2020, 5:25:38 PM EDT, Evan Hand <elhandjr@...> wrote:


Rob,
I am not sure what you mean by the PTT Ground.  The PTT circuit is the same for all of the versions, the only difference is that the 3.5mm jack is soldered directly to the v6 board.  The PTT signal line, the one that is grounded to turn on the transmitter, is the same on both.  That is the sleeve of the 3.5mm plug is ground and the PTT signal is the ring.  To turn on the TX/RX relay you ground the ring to the sleeve. 

I see your choices as either building an external box to parallel the PTT grounding from the mic like that shown in the article that Rob provided, or you will need to tap into any of a number of points directly on the mainboard.  You could just parallel the linear PTT relay coil that you would add across either K1 or K3 coil on the mainboard.  That would reduce the parts required slightly as the protection diodes are already there.  Then connect the contact that would be the PTT signal to the linear.

Do you know the type of signal that the linear requires?  Is it ground or a dc voltage?  This will impact the type of interface you will need to provide.  The one in the article assumes that a grounded PTT line to the amp will put it into transmit mode.  The other possibility is a DC voltage to turn on a relay, or in one case a bias voltage, internal to the amp.

I will state again that these are just ideas on my part.  I have not done them as of yet.  I am still working on the cheap Chinese linear amp kit that I bought and built.  It has harmonic issues on it's own that I need to address.

73
Evan
AC9TU


Evan Hand
 

No, I bought a DIY Kit SSB 70W linear.  It is a kit of parts that is not a complete linear as you still need heatsink and LPF.  I looked at the amp you are looking at and have read some good reviews.  When it comes down to it, I already have an ICOM IC-7300, could not justify buying an already assembled amp.  I could just use the 7300.

Here is the link:
https://www.ebay.com/p/1380231250
And the filter kit
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2047675.m570.l1313&_nkw=3.5MHz-30MHz+HF+Low+Pass+Filter+LPF+Kit+100W&_sacat=0
Do not be fooled by the cost.  After you get everything that you need you are close to $100 without a case, switches, and connectors.  Good if you want to learn how to build and test this type of device.  It has been a significant amount of research and modification to get it to sort of work.  Still fiddling.

This is just my experience.  Others may have had different results do to different skills or prior experience.
73
Evan
AC9TU 


Bob Lunsford
 

Thanks, Evan. Interesting info. I'll check it out.

Bob — KK5R

On Saturday, August 29, 2020, 6:23:17 PM EDT, Evan Hand <elhandjr@...> wrote:


No, I bought a DIY Kit SSB 70W linear.  It is a kit of parts that is not a complete linear as you still need heatsink and LPF.  I looked at the amp you are looking at and have read some good reviews.  When it comes down to it, I already have an ICOM IC-7300, could not justify buying an already assembled amp.  I could just use the 7300.

Here is the link:
https://www.ebay.com/p/1380231250
And the filter kit
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2047675.m570.l1313&_nkw=3.5MHz-30MHz+HF+Low+Pass+Filter+LPF+Kit+100W&_sacat=0
Do not be fooled by the cost.  After you get everything that you need you are close to $100 without a case, switches, and connectors.  Good if you want to learn how to build and test this type of device.  It has been a significant amount of research and modification to get it to sort of work.  Still fiddling.

This is just my experience.  Others may have had different results do to different skills or prior experience.
73
Evan
AC9TU 


Bob Lunsford
 

On Saturday, August 29, 2020, 6:23:17 PM EDT, Evan Hand <elhandjr@...> wrote:


No, I bought a DIY Kit SSB 70W linear.  It is a kit of parts that is not a complete linear as you still need heatsink and LPF.  I looked at the amp you are looking at and have read some good reviews.  When it comes down to it, I already have an ICOM IC-7300, could not justify buying an already assembled amp.  I could just use the 7300.

Here is the link:
https://www.ebay.com/p/1380231250
And the filter kit
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2047675.m570.l1313&_nkw=3.5MHz-30MHz+HF+Low+Pass+Filter+LPF+Kit+100W&_sacat=0
Do not be fooled by the cost.  After you get everything that you need you are close to $100 without a case, switches, and connectors.  Good if you want to learn how to build and test this type of device.  It has been a significant amount of research and modification to get it to sort of work.  Still fiddling.

This is just my experience.  Others may have had different results do to different skills or prior experience.
73
Evan
AC9TU 


Bob Lunsford
 

Evan, I found that the 45W amp I showed you first does not have 20M. Surprise-surprise. This throws a new wrinkle in the mix.

Bob — KK5R

On Saturday, August 29, 2020, 7:14:45 PM EDT, Bob Lunsford via groups.io <nocrud222@...> wrote:


On Saturday, August 29, 2020, 6:23:17 PM EDT, Evan Hand <elhandjr@...> wrote:


No, I bought a DIY Kit SSB 70W linear.  It is a kit of parts that is not a complete linear as you still need heatsink and LPF.  I looked at the amp you are looking at and have read some good reviews.  When it comes down to it, I already have an ICOM IC-7300, could not justify buying an already assembled amp.  I could just use the 7300.

Here is the link:
https://www.ebay.com/p/1380231250
And the filter kit
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2047675.m570.l1313&_nkw=3.5MHz-30MHz+HF+Low+Pass+Filter+LPF+Kit+100W&_sacat=0
Do not be fooled by the cost.  After you get everything that you need you are close to $100 without a case, switches, and connectors.  Good if you want to learn how to build and test this type of device.  It has been a significant amount of research and modification to get it to sort of work.  Still fiddling.

This is just my experience.  Others may have had different results do to different skills or prior experience.
73
Evan
AC9TU 


Bob Lunsford
 

On Saturday, August 29, 2020, 7:19:51 PM EDT, Bob Lunsford via groups.io <nocrud222@...> wrote:


Evan, I found that the 45W amp I showed you first does not have 20M. Surprise-surprise. This throws a new wrinkle in the mix.

Bob — KK5R

On Saturday, August 29, 2020, 7:14:45 PM EDT, Bob Lunsford via groups.io <nocrud222@...> wrote:


On Saturday, August 29, 2020, 6:23:17 PM EDT, Evan Hand <elhandjr@...> wrote:


No, I bought a DIY Kit SSB 70W linear.  It is a kit of parts that is not a complete linear as you still need heatsink and LPF.  I looked at the amp you are looking at and have read some good reviews.  When it comes down to it, I already have an ICOM IC-7300, could not justify buying an already assembled amp.  I could just use the 7300.

Here is the link:
https://www.ebay.com/p/1380231250
And the filter kit
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2047675.m570.l1313&_nkw=3.5MHz-30MHz+HF+Low+Pass+Filter+LPF+Kit+100W&_sacat=0
Do not be fooled by the cost.  After you get everything that you need you are close to $100 without a case, switches, and connectors.  Good if you want to learn how to build and test this type of device.  It has been a significant amount of research and modification to get it to sort of work.  Still fiddling.

This is just my experience.  Others may have had different results do to different skills or prior experience.
73
Evan
AC9TU 


Evan Hand
 

Not sure if you need the fans with the 45W MX-P50A HF.  The reviews that I read indicated that the devices used were conservatively rated and no indications of excessive heat.  For the kit that I bought you do need the fans.

I could not find any reviews for the last amp that you listed.  From what I could see, it is a good deal IF the power and harmonics are correct.  I would recommend that you do a more diligent search on the internet for reviews prior to purchasing. 

The 
DIY kits 100W SSB linear HF Power Amplifier you listed does NOT include an LPF.  An LPF is required to meet signal purity requirements.  The good news is the devices they are using are better than the IRF510 in most amplifiers like this.

Of all that you have listed, to meet the 20-meter requirement, the last one looks the best, assuming that you can find favorable reviews.
73
Evan
AC9TU


OZ6TI Ole
 

Hi

 

As for the LPF, there are lots available on ebay and aliexpress. Almost all have relays for band selection. As ubitx cannot control these, then you have to select the right band by means of some switch, I guess. Does “commercial” transceivers like yaesu support this automatically?

 

I guess you could programme the ubitx and add some relays to do the autoselection?

 

73, Ole

OZ6TI

 

Fra: BITX20@groups.io <BITX20@groups.io> På vegne af Evan Hand
Sendt: 30. august 2020 01:50
Til: BITX20@groups.io
Emne: Re: [BITX20] Ubitx Ver 6 need PTT circuit for Linear AMP

 

Not sure if you need the fans with the 45W MX-P50A HF.  The reviews that I read indicated that the devices used were conservatively rated and no indications of excessive heat.  For the kit that I bought you do need the fans.

I could not find any reviews for the last amp that you listed.  From what I could see, it is a good deal IF the power and harmonics are correct.  I would recommend that you do a more diligent search on the internet for reviews prior to purchasing. 

The 
DIY kits 100W SSB linear HF Power Amplifier you listed does NOT include an LPF.  An LPF is required to meet signal purity requirements.  The good news is the devices they are using are better than the IRF510 in most amplifiers like this.

Of all that you have listed, to meet the 20-meter requirement, the last one looks the best, assuming that you can find favorable reviews.
73
Evan
AC9TU


 

What's it providing that the other one doesnt?

No heatsink or LPF with the kit :-/

73.   Mark


Howard Fidel
 

I just redid my uBitx with a 70 watt amp. For the filters, I redid the filters on the uBitx with larger ferrrites, and  100V caps. I route the uBitx amp output before the filters to the amp, and then the amp output to the uBitx filter input. Works just like the uBitx barefoot, but with higher power when the amp is switched in. The amp has a relay for in/out.

73
Howard
W2HFF


Evan Hand
 

Howard,
Did you test the signal for harmonics and spurs after the mod with and without the 70W PA on?  There is a history of poor signal purity of the uBITX series from HF Signals.  That was solved for the barefoot boards with the v5 update.  Not sure what higher power through the LPF section will do to the spurs issues solved with the v5 and later boards.

I would like to try this approach for one of my uBITX builds but would like to know that there is not an issue with signal purity before going down that road myself.  Any information would be appreciated.

73
Evan
AC9TU


Howard Fidel
 


Evan
I have a V3 board. It certainly has the spur issue on SSB. I did change the filter design somewhat and the relays.  I was not successful with some of the other spur reduction mods. I decided that for V3 the best approach is to change the LPFs to band pass filters but I have not done that.  The LPFs don't remove the spurs just the harmonics. With V5 you should have no issues with spurs and the amp can't create spurs so you should be ok with my approach 

Howard 


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Evan Hand
 

Howard,
Thank you for the response.   I have 2 v4 boards, one that I wanted to add the amp to.  The relay replacement seemed to solve the harmonic issues (tested with an RSP1A and Spectrum Analyzer software), but have not yet done the spurs fix (I do not operate it on SSB above 20 meters).

Again, thank you for getting back to me.
73
Evan
AC9TU