Topics

Wow... 15 volts in and a bunch out..

Kevin Rea
 

So, I thought I would try just 15 volts straight into the rear power connector..
wow.. 30 watts ssb on 20 meters into a dummy load.

i have three temp monitors on it to see what all the areas do, so far nothing really hot..

kevin

Kevin Rea
 

so far, the hottest thing i have found is that large transistor that sticks out the side of the raduino, on the front side of the unit, don't know
what that part is for, possibly audio ?  anyway, i monitor it at about 135 degrees fahrenheit.

kevin

Howard Fidel
 

7805 5 volt regulator for the Arduino. Adding a small clip on heat sink is  good idea.

On 8/18/2018 8:58 PM, Kevin Rea wrote:
so far, the hottest thing i have found is that large transistor that sticks out the side of the raduino, on the front side of the unit, don't know
what that part is for, possibly audio ?  anyway, i monitor it at about 135 degrees fahrenheit.

kevin


Kevin Rea
 

Ok, i just put one on it.
on it's datasheet, looks like it can operate up to about 257 degrees fahrenheit, so at 135 degrees it seems safe.

kevin

Howard Fidel
 

Cool. Yes, it can safely work at that temp. Some people have put a resistor in series to reduce the temp, but the heat sink is easier. The resistor is a good idea if you are much closer to the power limit.

Howard

On 8/18/2018 9:31 PM, Kevin Rea wrote:
Ok, i just put one on it.
on it's datasheet, looks like it can operate up to about 257 degrees fahrenheit, so at 135 degrees it seems safe.

kevin


Kevin Rea
 

what size resistor Howard ? and, where is it placed exactly ?

kevin

RCBoatGuy
 

From the sounds of it, this temperature measurement was taken in open air, indoors @ room temperature.  It will get considerably hotter in an enclosure, and even hotter yet if that enclosure is outside in direct sunlight on a summers day. 

I strongly recommend both the heat sink and the resistor, especially if you plan on using this outdoors. 

73,

Carl, K0MWC

Skip Davis
 

Kevin, I added a 47 ohm resistor between puns 15/16 and the voltage regulator. This reduced the voltage drop across the regulator which reduced the amount of heat that needed to be dissipated by the regulator. I used a 1/4 watt resistor and don’t see any overheating of that resistor. 

Skip Davis, NC9O

On Aug 18, 2018, at 23:22, Kevin Rea <reakevinscott@...> wrote:

what size resistor Howard ? and, where is it placed exactly ?

kevin

Tom, wb6b
 

So a question. I know some of the power boost suggestions like shorting out parts the were put there to provide stability in the amplifiers or overdriving the audio, do indeed increase power, but at the cost of vastly increasing unwanted emissions.

However, are we working too hard to optimize the RF chain, finding super transistors and such, just for the sake of being tied to 12 volts. I don't want to see my audio amp IC go up in flames or make the relays melt, but what if we selectively applied an increased voltage, say 18 volts to pull a possible voltage out of the air, and applied that to the finals, the infamous Q90, and Q92, 93, 96, 97, 911, 912, and possibility further back in the TX amplifier chain?

Would that result in a RF chain that has more useful gain to work with and allow more headroom for other power leveling efforts?

I have some new 150W boost converters coming from Amazon. They are around $4 each. It seems like for that low cost, freeing ourselves from the bonds of 12 volts may be worth it.

On a side note the boost converts have the worrisome name of "Gowoops". Sounds like if they live up to their name I should expect more smoke than volts to come out of them.

Tom, wb6b

ajparent1/KB1GMX <kb1gmx@...>
 

Tom,

Back when I was resorting to the full bag of tricks the goal was not more power!
The goal was even power from 80 through 10 and improved distortion levels.

Alas, the were other issues found that superseded that work.  


For the moment it was and is possible to improve the amp.  The problem is 
All the spurious product presented to the amp would be amplified as well.
That and the basic modulator/filter/if had issues as well.  The result was a
good amp would be largely wasted.  Then a collective bunch of us noted
other things like compromised output filters that allowed all that excess to
escape.  I like Warren reached the point that salvage was not possible.
I did literally cut the board up to investigate root cause issues and the
conclusions are harsh.

The amp is a disaster.  The radio is 80-10 the amp never made it to 20m.
The choice of devices and layout were big issues and the IRF510 was
blamed for most of it and it was already a mess before we got to them. 
Plain english, the 2n3904 was a weak choice and poorly implemented
as asking it for more than 10DB at at 30mhz was impossible.   Layout
made for further issues with stability.

Output filters due to layout.  Again layout at HF still counts.

Lack of band pass filters before the amp.  I'll repeat what I've said 
garbage in nets garbage out, minimal filtering is wishful thinking.

IF gain issues.  Asking for 18db from 2n3904s is not engineering its wishful.
There are a few that will and many that will not.  IF one asked for 10db it
would not be an issue.  On that same boat , the high gain of the transmit
path leads to spurious signal creation.  To go from the modulator to the last
mixer no more than 16db of gain is needed across the 12 and 45 mhz if
for transmit.  We have on average 32 to 28db of gain.  Too much gain
causes problems those include poor carrier to signal and overload.

On top of that  The "12mhz" IF and filter layout made it susceptible to
the 11.997mhz carrier further reducing the carrier to modulation. 
Board layout is the major issue not circuit failure.

The above applies to transmit only but echos of that are in the
receiver as birdies and spurious responses.

The whole 12V thing was a result of the TDA2822.  My board I put in a
regulated voltage for the TDA and end of issue. By doing that 13.8 was
the standard.  However that does not fix all the broken.  We or at least
I was not tied to 12V.  If you think fixing that by running 20V or more 
is a solution its clearly a CB solution.

The bottom line is mod like mad for power and your amping up a
lot of spurious trash and putting it on the band.

Allison

ajparent1/KB1GMX <kb1gmx@...>
 

Tom,

As a follow up I've built my own amp and also worked with Hands on his and 
as a result I have two different amps that can do 3-30mhz with nearly flat
power and very linear.  That's at 12V (not 12V is really 13.8 noninal).

It I take both of those to 20V I get 20+ watts of clean for the effort
but consider that the design was for 10W with headroom so that
10W isn't full up distorted.

As to using a boot converter...  Hope the switching noise doesn't show up.

The relays will tolerate 16V all day.  The rest should be regulated anyway.

Allison

Gordon Gibby <ggibby@...>
 

Allison, what about adding an additional stage after the last mixer in the transmitter lineup? Better choice of transistors (replace Q90 and maybe the other 3904’s)... add (insert) a tiny daughter board with an additional stage, could that allow for operating the existing stages at more reasonable gain goals with more negative feedback?   

Further  Having intercepted the signal it might also give a point for bandpass filters to be easily inserted—-

You might laugh at it, but even a single or dual-stage preselecter with variable capacitor(s) tuning a parallel filter, (like what I had on my heat kits), once marked for the proper positions for each band, might significantly clean up most of them except for the 21 MHz debacle.  — tune for maximum signal output making sure you’re near the correct Mark.    If too much to ask from one inductor, add a tap for the higher end 

 Gordon




On Aug 21, 2018, at 11:51, ajparent1/KB1GMX <kb1gmx@...> wrote:

Tom,

Back when I was resorting to the full bag of tricks the goal was not more power!
The goal was even power from 80 through 10 and improved distortion levels.

Alas, the were other issues found that superseded that work.  


For the moment it was and is possible to improve the amp.  The problem is 
All the spurious product presented to the amp would be amplified as well.
That and the basic modulator/filter/if had issues as well.  The result was a
good amp would be largely wasted.  Then a collective bunch of us noted
other things like compromised output filters that allowed all that excess to
escape.  I like Warren reached the point that salvage was not possible.
I did literally cut the board up to investigate root cause issues and the
conclusions are harsh.

The amp is a disaster.  The radio is 80-10 the amp never made it to 20m.
The choice of devices and layout were big issues and the IRF510 was
blamed for most of it and it was already a mess before we got to them. 
Plain english, the 2n3904 was a weak choice and poorly implemented
as asking it for more than 10DB at at 30mhz was impossible.   Layout
made for further issues with stability.

Output filters due to layout.  Again layout at HF still counts.

Lack of band pass filters before the amp.  I'll repeat what I've said 
garbage in nets garbage out, minimal filtering is wishful thinking.

IF gain issues.  Asking for 18db from 2n3904s is not engineering its wishful.
There are a few that will and many that will not.  IF one asked for 10db it
would not be an issue.  On that same boat , the high gain of the transmit
path leads to spurious signal creation.  To go from the modulator to the last
mixer no more than 16db of gain is needed across the 12 and 45 mhz if
for transmit.  We have on average 32 to 28db of gain.  Too much gain
causes problems those include poor carrier to signal and overload.

On top of that  The "12mhz" IF and filter layout made it susceptible to
the 11.997mhz carrier further reducing the carrier to modulation. 
Board layout is the major issue not circuit failure.

The above applies to transmit only but echos of that are in the
receiver as birdies and spurious responses.

The whole 12V thing was a result of the TDA2822.  My board I put in a
regulated voltage for the TDA and end of issue. By doing that 13.8 was
the standard.  However that does not fix all the broken.  We or at least
I was not tied to 12V.  If you think fixing that by running 20V or more 
is a solution its clearly a CB solution.

The bottom line is mod like mad for power and your amping up a
lot of spurious trash and putting it on the band.

Allison

Jerry Gaffke
 

An MMIC between Q90 and RV1 is an easy way to add an extra stage.
  https://groups.io/g/BITX20/message/51211
Of course, you still have to adjust the other stages to distribute the gain properly.
Including those IF amps.
And to really clean stuff up, create a new board layout.
Rapidly becomes way more than most of us want to take on.

I think just operating the uBitx on 20,40,80m with an external LPF (or cleaned up on-board LPF's)
and with mike levels appropriate for 5 to 10 watts out is acceptable.
We may still have IMD issues, a somewhat unsuppressed suppressed carrier, some low level out-of-band spurs.
But such operation can meet our legal requirements.

I would not operate the uBitx with an external linear amp to boost power.
Not without a benchfull of gear to monitor the result.

Jerry

 


On Tue, Aug 21, 2018 at 09:06 AM, Gordon Gibby wrote:
Allison, what about adding an additional stage after the last mixer in the transmitter lineup? Better choice of transistors (replace Q90 and maybe the other 3904’s)... add (insert) a tiny daughter board with an additional stage, could that allow for operating the existing stages at more reasonable gain goals with more negative feedback?   
 
Further  Having intercepted the signal it might also give a point for bandpass filters to be easily inserted—-
 
You might laugh at it, but even a single or dual-stage preselecter with variable capacitor(s) tuning a parallel filter, (like what I had on my heat kits), once marked for the proper positions for each band, might significantly clean up most of them except for the 21 MHz debacle.  — tune for maximum signal output making sure you’re near the correct Mark.    If too much to ask from one inductor, add a tap for the higher end 
 
 Gordon

Gordon Gibby <ggibby@...>
 

Hi Jerry, can you produce a schematic with parts numbers on exactly how to do that?   I’ve never used one of those components before. 

It should be easy to reduce gain in previous day just by simply changing some resistors to higher values in the emitter circuits.— though I haven’t looked at them

Gordon



On Aug 21, 2018, at 13:03, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

An MMIC between Q90 and RV1 is an easy way to add an extra stage.
  https://groups.io/g/BITX20/message/51211
Of course, you still have to adjust the other stages to distribute the gain properly.
Including those IF amps.
And to really clean stuff up, create a new board layout.
Rapidly becomes way more than most of us want to take on.

I think just operating the uBitx on 20,40,80m with an external LPF (or cleaned up on-board LPF's)
and with mike levels appropriate for 5 to 10 watts out is acceptable.
We may still have IMD issues, a somewhat unsuppressed suppressed carrier, some low level out-of-band spurs.
But such operation can meet our legal requirements.

I would not operate the uBitx with an external linear amp to boost power.
Not without a benchfull of gear to monitor the result.

Jerry

 

On Tue, Aug 21, 2018 at 09:06 AM, Gordon Gibby wrote:
Allison, what about adding an additional stage after the last mixer in the transmitter lineup? Better choice of transistors (replace Q90 and maybe the other 3904’s)... add (insert) a tiny daughter board with an additional stage, could that allow for operating the existing stages at more reasonable gain goals with more negative feedback?   
 
Further  Having intercepted the signal it might also give a point for bandpass filters to be easily inserted—-
 
You might laugh at it, but even a single or dual-stage preselecter with variable capacitor(s) tuning a parallel filter, (like what I had on my heat kits), once marked for the proper positions for each band, might significantly clean up most of them except for the 21 MHz debacle.  — tune for maximum signal output making sure you’re near the correct Mark.    If too much to ask from one inductor, add a tap for the higher end 
 
 Gordon

Jerry Gaffke
 

Oh, I haven't done it.
Just kibitzing.

It could be another npn gain stage, just that an mmic involves fewer parts,
so easier to patch in ugly-style on the bottom ground plane.

An example might be U2 of Farhan's specan:
    https://drive.google.com/file/d/0BzRNYeu10K6DdE1CSDVfZUdTdzg/view
L5 is not totally needed, you just lose a little gain if all you have is a resistor between +12v and the output of U2.
The input and output of U2 must be capacitively coupled to adjoining stages.
The input and output of U2 are fixed at 50 ohms.

So basically a 4 pin IC, a resistor, and two AC coupling caps.

The MAV11 is an older MMIC, though certainly viable the manufacturer doesn't sell them at less than quantity 20:
    https://www.minicircuits.com/WebStore/dashboard.html?model=MAV-11SM%2B
Beware of ebay clones, they may or may not work for you.
There are hundreds of MMIC's available, at various power levels, gains, noise figures, frequency ranges, packages,  ...
Choosing one at random, take a look at the datasheet for the BGA616,  Mouser pnum   726-BGA616H6327XT
    https://www.mouser.com/datasheet/2/196/BGA616-90471.pdf

Jerry, KE7ER



On Tue, Aug 21, 2018 at 10:17 AM, Gordon Gibby wrote:
Hi Jerry, can you produce a schematic with parts numbers on exactly how to do that?   I’ve never used one of those components before. 
 
It should be easy to reduce gain in previous day just by simply changing some resistors to higher values in the emitter circuits.— though I haven’t looked at them
 
Gordon

Gordon Gibby <ggibby@...>
 

So I read the BGA616.   $1.50 from Digikey  

https://www.digikey.com/product-detail/en/infineon-technologies/BGA616H6327XTSA1/BGA616H6327XTSA1CT-ND/2410159


I see you provide a 33 ohm collector load resistor, drive it with 6 volts or less, and it SEEMS to have a 50 ohm input impedance and its own biasing.   


Pretty interesting little amplifier.   Supposed to provide a power gain of 20 dB.    Seems like more than we really need but extra gain is probably easy to throw away with MORE negative emitter feedback resistance, instead of fighting for every bit we can pull out of 2N-3904 or other transistors....


Are there any downsides that you see to adding this after Q90?


Gordon



From: BITX20@groups.io <BITX20@groups.io> on behalf of Jerry Gaffke via Groups.Io <jgaffke@...>
Sent: Tuesday, August 21, 2018 1:58 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Wow... 15 volts in and a bunch out..
 
Oh, I haven't done it.
Just kibitzing.

It could be another npn gain stage, just that an mmic involves fewer parts,
so easier to patch in ugly-style on the bottom ground plane.

An example might be U2 of Farhan's specan:
    https://drive.google.com/file/d/0BzRNYeu10K6DdE1CSDVfZUdTdzg/view
L5 is not totally needed, you just lose a little gain if all you have is a resistor between +12v and the output of U2.
The input and output of U2 must be capacitively coupled to adjoining stages.
The input and output of U2 are fixed at 50 ohms.

So basically a 4 pin IC, a resistor, and two AC coupling caps.

The MAV11 is an older MMIC, though certainly viable the manufacturer doesn't sell them at less than quantity 20:
    https://www.minicircuits.com/WebStore/dashboard.html?model=MAV-11SM%2B
Beware of ebay clones, they may or may not work for you.
There are hundreds of MMIC's available, at various power levels, gains, noise figures, frequency ranges, packages,  ...
Choosing one at random, take a look at the datasheet for the BGA616,  Mouser pnum   726-BGA616H6327XT
    https://www.mouser.com/datasheet/2/196/BGA616-90471.pdf

Jerry, KE7ER



On Tue, Aug 21, 2018 at 10:17 AM, Gordon Gibby wrote:
Hi Jerry, can you produce a schematic with parts numbers on exactly how to do that?   I’ve never used one of those components before. 
 
It should be easy to reduce gain in previous day just by simply changing some resistors to higher values in the emitter circuits.— though I haven’t looked at them
 
Gordon

MadRadioModder
 

WARNING:  Max Vd on that part is 4.5VDC !!!

 

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Gordon Gibby
Sent: Tuesday, August 21, 2018 2:30 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Wow... 15 volts in and a bunch out..

 

So I read the BGA616.   $1.50 from Digikey  

https://www.digikey.com/product-detail/en/infineon-technologies/BGA616H6327XTSA1/BGA616H6327XTSA1CT-ND/2410159

 

I see you provide a 33 ohm collector load resistor, drive it with 6 volts or less, and it SEEMS to have a 50 ohm input impedance and its own biasing.   

 

Pretty interesting little amplifier.   Supposed to provide a power gain of 20 dB.    Seems like more than we really need but extra gain is probably easy to throw away with MORE negative emitter feedback resistance, instead of fighting for every bit we can pull out of 2N-3904 or other transistors....

 

Are there any downsides that you see to adding this after Q90?

 

Gordon

 


From: BITX20@groups.io <BITX20@groups.io> on behalf of Jerry Gaffke via Groups.Io <jgaffke@...>
Sent: Tuesday, August 21, 2018 1:58 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Wow... 15 volts in and a bunch out..

 

Oh, I haven't done it.
Just kibitzing.

It could be another npn gain stage, just that an mmic involves fewer parts,
so easier to patch in ugly-style on the bottom ground plane.

An example might be U2 of Farhan's specan:
    https://drive.google.com/file/d/0BzRNYeu10K6DdE1CSDVfZUdTdzg/view
L5 is not totally needed, you just lose a little gain if all you have is a resistor between +12v and the output of U2.
The input and output of U2 must be capacitively coupled to adjoining stages.
The input and output of U2 are fixed at 50 ohms.

So basically a 4 pin IC, a resistor, and two AC coupling caps.

The MAV11 is an older MMIC, though certainly viable the manufacturer doesn't sell them at less than quantity 20:
    https://www.minicircuits.com/WebStore/dashboard.html?model=MAV-11SM%2B
Beware of ebay clones, they may or may not work for you.
There are hundreds of MMIC's available, at various power levels, gains, noise figures, frequency ranges, packages,  ...
Choosing one at random, take a look at the datasheet for the BGA616,  Mouser pnum   
726-BGA616H6327XT
    https://www.mouser.com/datasheet/2/196/BGA616-90471.pdf

Jerry, KE7ER



On Tue, Aug 21, 2018 at 10:17 AM, Gordon Gibby wrote:

Hi Jerry, can you produce a schematic with parts numbers on exactly how to do that?   I’ve never used one of those components before. 

 

It should be easy to reduce gain in previous day just by simply changing some resistors to higher values in the emitter circuits.— though I haven’t looked at them

 

Gordon


Virus-free. www.avg.com

--

…_. _._

Ken
 

If they're similar to MARS MMIC, input and output MUST be 50 ohms.

73

Ken VA3ABN

On Tue, Aug 21, 2018 at 3:52 PM, MadRadioModder <madradiomodder@...> wrote:

WARNING:  Max Vd on that part is 4.5VDC !!!

 

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Gordon Gibby
Sent: Tuesday, August 21, 2018 2:30 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Wow... 15 volts in and a bunch out..

 

So I read the BGA616.   $1.50 from Digikey  

https://www.digikey.com/product-detail/en/infineon-technologies/BGA616H6327XTSA1/BGA616H6327XTSA1CT-ND/2410159

 

I see you provide a 33 ohm collector load resistor, drive it with 6 volts or less, and it SEEMS to have a 50 ohm input impedance and its own biasing.   

 

Pretty interesting little amplifier.   Supposed to provide a power gain of 20 dB.    Seems like more than we really need but extra gain is probably easy to throw away with MORE negative emitter feedback resistance, instead of fighting for every bit we can pull out of 2N-3904 or other transistors....

 

Are there any downsides that you see to adding this after Q90?

 

Gordon

 


From: BITX20@groups.io <BITX20@groups.io> on behalf of Jerry Gaffke via Groups.Io <jgaffke@...>
Sent: Tuesday, August 21, 2018 1:58 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Wow... 15 volts in and a bunch out..

 

Oh, I haven't done it.
Just kibitzing.

It could be another npn gain stage, just that an mmic involves fewer parts,
so easier to patch in ugly-style on the bottom ground plane.

An example might be U2 of Farhan's specan:
    https://drive.google.com/file/d/0BzRNYeu10K6DdE1CSDVfZUdTdzg/view
L5 is not totally needed, you just lose a little gain if all you have is a resistor between +12v and the output of U2.
The input and output of U2 must be capacitively coupled to adjoining stages.
The input and output of U2 are fixed at 50 ohms.

So basically a 4 pin IC, a resistor, and two AC coupling caps.

The MAV11 is an older MMIC, though certainly viable the manufacturer doesn't sell them at less than quantity 20:
    https://www.minicircuits.com/WebStore/dashboard.html?model=MAV-11SM%2B
Beware of ebay clones, they may or may not work for you.
There are hundreds of MMIC's available, at various power levels, gains, noise figures, frequency ranges, packages,  ...
Choosing one at random, take a look at the datasheet for the BGA616,  Mouser pnum   
726-BGA616H6327XT
    https://www.mouser.com/datasheet/2/196/BGA616-90471.pdf

Jerry, KE7ER



On Tue, Aug 21, 2018 at 10:17 AM, Gordon Gibby wrote:

Hi Jerry, can you produce a schematic with parts numbers on exactly how to do that?   I’ve never used one of those components before. 

 

It should be easy to reduce gain in previous day just by simply changing some resistors to higher values in the emitter circuits.— though I haven’t looked at them

 

Gordon


Virus-free. www.avg.com

--

…_. _._


Kevin Rea
 

the temperatures taken with a sensor probe that sits on the heat sink of that transistor inside the enclosure closed up, and I would never take it outside. I do all of my radio stuff in the house.

Jerry Gaffke
 

Max supply voltage on an MMIC is a function of the supply resistor you choose.
Only the output pin itself is limited to 4.5v absolute max for supply voltage with respect to ground,
and that does not include the AC output signal that might be riding on top of it. 

Look at the top left graph on page 8 of the BGA616 datasheet 
showing device supply current vs supply resistor in ohms.
At zero ohms, the BGA616 looks like a zener diode with a knee around 4.0 volts.

Now look at the test circuit in fig 2 on page 6.
They are powering it from a 6v rail through a series 33 ohm resistor.
So the device is sucking (6v-4v)/33 = 60ma.
Table 3 on page 5 says the total device current is 60ma.
Coincidence?

So just think of it as a zener diode, as far as supply voltage goes.
If you want to feed it from 12v, then use a resistor of (12v-4v)/60ma = 133 ohms.
You lose some gain, because that 133 ohms is competing with your 50 ohm load at the output
for the available AC output power.  If that matters, add an inductor in series with the 133 ohms.
If running without the inductor, you are much better off feeding it from 12v than from 6v.

A string of two or three MMIC"s plus the Hans/Allison design for the BS170+IRF510 push-pull driver and final
could make a very nice power amp for the uBitx.

Downsides?
The MMIC's are not as cheap as the 2n3904's, and are not necessarily efficient with power.
The *Bitx* radios are back to basics, trying to do everything they can with npn transistors,
and an MMIC does not quite fit in.
But they are easy to use, and in a 50 ohm environment there is no need for transformers

Jerry, KE7ER 

 


On Tue, Aug 21, 2018 at 12:52 PM, MadRadioModder wrote:

WARNING:  Max Vd on that part is 4.5VDC !!!