Date   
Re: Amplifier Talk- Communications Concepts

 

Sorry for using "CB amp" as a description,

It isn't a real specification anyway.  I just meant a type of amplifier that was gererally of a simple design that doesn't have a lot of features.  As Alison says, e.g. the EB63 uses basic diode biasing which needs high current in order to maintain a stable bias.  This results in low efficiency and higher battery drain.

Such types might also might be considered a single band design, as there is often only one (or none) lowpass filter.  They also generally have no gain compensation, which means uneven power output has you change bands, which would require transmitter power adjustment to keep from overdriving and burning out the final transistors which are not cheap.

The latter point really makes it not a good match for the ubitx since the transciever already has quite uneven power ouput with good power on the low bands and less and less as you go up.  An uncompensated amplifier will also do the same thing so that can be a troublesome thing to handle.

The AN763 would be a better match up as it has gain compensation built into the design already (no need to figure it out on your own, or extra parts to buy).  It also has a more efficient design for both biasing and for the final transformer (less heat and lower current draw).

Alison, I don't quite get what you said about the copper heat spreader and the AN762?  Reading the construction notes for both the EB63 and the AN763, I couldn't find a mention of that, or that the AN763 would have any more rare parts than the EB63?  Both seemed to be complete kits that only required a large aluminum heatsink and a heatsink fan (besides a case and lowpass filters and switches).

73,


Mark.

Re: Project : Ubitx go box with batteries (topic will be updated upon works done)

Adrien F4IJA
 

So, my uBitx is almost finished !

I haven't made some QSO for now, but I tested it like a WSPR beacon and it's OK (6800km of report max).

Here some views of the beast :


--
73's
Adrien F4IJA
https://www.qrz.com/db/F4IJA

Amplifier board available - cheap

Woody
 

I have rebuilt my HF linear (case and all) and used a BLF-188XR.  Had smoked my previous amp board (AN-758) and just set it aside.  Hate to see it go to waste.  Keep in mind that it will need low pass output filters for the bands desired.
So, wonder if anyone would be interested in owning it... 
 
Asking $25 for the board, no shipping charge (Priority Mail) in the US lower 48, via PayPal  -  Needs new PA transistors, at least.

Minimum gain of the MRF429 is 13db.  For about 8 to 9 watts drive, should make at least 180 watts out.

See applications note (this board is one of the multiple boards shown in the note for a KW amp:
https://www.communication-concepts.com/content/AN758/AN758_Application_Note.pdf

The kit info and downloadable info can be found at:
http://www.communication-concepts.com/an758/
&
http://www.communication-concepts.com/an758-1/ 
They sell the kit for $159.35 (including transistors)

Replacement PAs :  http://www.communication-concepts.com/mrf429mp/   ($106 for matched pair)

The MFR429s must be replaced.  Other semiconductors (See * in image) must be checked and replaced if bad.
The bias regulator (Silver can in pix, is SG FTB016) operation should be verified before installing new PAs !   The regulator on board is a SG FTB016.   In the appnote schematic, the device is a MC1723.  See: https://www.utsource.net/itm/p/302661.html?digipart=1     I am not certain, but suspect any pin compatible 723 regulator, in a TO-100 can package would work  -  If it needs to be replaced.

email me if any questions...
 
Woody  -  KZ4AK   (email good on QRZ)


Re: Amplifier Talk- Communications Concepts

Gordon Gibby
 

Thank you very much for that information, I will try either 450 ohms or 900 ohms, Little noninductive dummy load and a step up balun to match, that should work in the 1 to 3 watt range if I my calculations are correct;  you’ve given me excellent guidance.




On Sep 15, 2019, at 09:21, ajparent1/KB1GMX <kb1gmx@...> wrote:

EXTERNAL EMAIL: Exercise caution with links and attachments.


Gordon,

Short form no.  The 6146 does require power to the grid to run though small.
the key thing is you need 25-50V p-p of RF and to do that across the grid resistor
and the 10-20pf of input capacitance.

The other part is that the bitx needs a stable load and the grid of 6146 is not that.

I'd think at several watts a 4:1 or maybe 9:1 would do.  However if yu want stability 
you have to load that transformer with resistance as the 6146 just like IRF510
is very intolerant of sloppy RF design and will oscillate to destruction.

Allison

Re: Overvoltage to Ubitx - now no receive

ajparent1/KB1GMX
 

Sumit,

You grossly over voltaged the LM386 audio amp.
Other parts are likely suspect but start  there.

Start at the speaker and work back.

FYI: the only parts that would tolerate more than 15-16V would be the finals IRF510.

Allison

Re: Amplifier Talk- Communications Concepts

ajparent1/KB1GMX
 

Gordon,

Short form no.  The 6146 does require power to the grid to run though small.
the key thing is you need 25-50V p-p of RF and to do that across the grid resistor
and the 10-20pf of input capacitance.

The other part is that the bitx needs a stable load and the grid of 6146 is not that.

I'd think at several watts a 4:1 or maybe 9:1 would do.  However if yu want stability 
you have to load that transformer with resistance as the 6146 just like IRF510
is very intolerant of sloppy RF design and will oscillate to destruction.

Allison

Overvoltage to Ubitx - now no receive

sumit basu
 

Hello,

My Ubitx ver 4 does not receive anything now. It was working fine till i tried fiddling with an AGC addon and an external audio amp. I was experimenting with the voltage supply and turned up the knob of my variable supply to increase voltage, at around 19~21v suddenly every thing went silent with a light 'pop' sound on the earphones. I went back to the original v4 audio setup minus all the addon's - but no sound at all.

It seems the transmit chain is working properly, as i can transmit to a dummy load and observe waterfall from a nearby SDR receiver, i can see and hear sending  with my cw key as well as my voice on the SDR receiver but with cw there is no sidetone volume at the ubitx speaker at all. Everthing is just quiet. I had the KD8CEC ver 1..2 installed and that part seems to be fine, i can PTT, send cw, voice and all menus are available and seem like woking, i can change all menu options and verify them using the ubitx manager as well as upload other versions. But no sound.

I tried the raduino diagnostic by VK2ETA and the tests are OK. I am trying to figure why the sidetone volume could not be heard , the only faint clicks i hear on the speaker are when my multimeter leads are touching the leads on Q72, Q73.

Could i have fried the Q72, Q73 as well as Q71 or any other transistor. I have some basic skills in electronics and i have checked resistor values in the audio amp section and they seem OK, also continuity from R250 till the base of Q71 is OK. Also, it seems to me Q72, Q73 might have failed as resistance values across all junctions seem very low. I had also tried  bypassing the audio section by connecting a speaker between the R250, R251 junction and ground - but again no sound of the sidetone.

I am trying to get the sidetone sound up first and then check the other receive sections - any help would be useful.

Sumit Basu

Re: Amplifier Talk- Communications Concepts

barry halterman
 

I have a complete EB63A that has not been built with a heat sink 165mm x 120mm x 40, 15 fins.
Anyone interested let me know.
Barry
K3BO

On Sun, Sep 15, 2019, 7:31 AM Gordon Gibby <ggibby@...> wrote:
Allison—

Can I ask your advice on a boat anchor project?  Soon I will start refurbishing more and more  HW 100s & SB 100s.   I read that only fractions of a white are needed to drive a 6146 amplifier (driving the grid).  It’s a very high input impedance.   We just learned how to make 1 to 49 baluns easily for End Fed half wave resonant antennas...(fantastic results!)

. would some 1:100 or so ferrite Baluns work well to feed the output of a micro Bitx  into the final amplifier stage one of these older boat anchor radios??

Gordon KX4Z




On Sep 14, 2019, at 23:48, ajparent1/KB1GMX <kb1gmx@...> wrote:

EXTERNAL EMAIL: Exercise caution with links and attachments.


Farhan,

Still around and busy.

Check out OZ1PIFs work.  I've run one section of that a 4x4 parallel push pull
on 6M to over 200W.  The yabut is you need 28V power at 15A!  At 12V that
doesn't work well.  The up side is to get that power not much drive is needed
and its easy to over drive it 5-6W was enough.  Its remarkably tough as I
haven't fried it.  The IMD is only OK.  However a really good and heavy built
low pass is needed as the first one with #18 air wound coils heated too much,
#14 wire solved that along with 500V metal clamp mica caps.

A pair of IRF510s can do 40-50w easy at 28V with 1-2W of drive. 
Parallel parts are harder as then you have parallel paths for
RF current to balance.  Cheat on the layout it becomes unstable
or poor power out.  Getting them to as high as 70mhz was not all
that hard if you pay attention to input and output impedance
they must be low for stability and reasonable power.

The 8 IRF510s are cheap but the total system is not cheap as you still
need a big heatsink (130mm by 130mm with 40mm fins  and a  fan) , TR
switching that can handle the power, and a package to put it all in. 
Cheap 28 or 48 volt switching  power supplies are not a solution as
often they are way to noisy on receive.

Things to consider 100W at 12V is about the limit using the right parts.
However the relays now have to be good for at least 5A and 100V
at the output and the input they can be fairly light.  With higher power
higher currents and voltage are the expected thing and parts like
#12 wire, 500V silver mica or ATC 800B are the required parts.

High power (more than 20 or so watts) tends to be expensive and
getting a reliable amp is never trivial task.

Allison

Re: Amplifier Talk- Communications Concepts

Gordon Gibby
 

Allison—

Can I ask your advice on a boat anchor project?  Soon I will start refurbishing more and more  HW 100s & SB 100s.   I read that only fractions of a white are needed to drive a 6146 amplifier (driving the grid).  It’s a very high input impedance.   We just learned how to make 1 to 49 baluns easily for End Fed half wave resonant antennas...(fantastic results!)

. would some 1:100 or so ferrite Baluns work well to feed the output of a micro Bitx  into the final amplifier stage one of these older boat anchor radios??

Gordon KX4Z




On Sep 14, 2019, at 23:48, ajparent1/KB1GMX <kb1gmx@...> wrote:

EXTERNAL EMAIL: Exercise caution with links and attachments.


Farhan,

Still around and busy.

Check out OZ1PIFs work.  I've run one section of that a 4x4 parallel push pull
on 6M to over 200W.  The yabut is you need 28V power at 15A!  At 12V that
doesn't work well.  The up side is to get that power not much drive is needed
and its easy to over drive it 5-6W was enough.  Its remarkably tough as I
haven't fried it.  The IMD is only OK.  However a really good and heavy built
low pass is needed as the first one with #18 air wound coils heated too much,
#14 wire solved that along with 500V metal clamp mica caps.

A pair of IRF510s can do 40-50w easy at 28V with 1-2W of drive. 
Parallel parts are harder as then you have parallel paths for
RF current to balance.  Cheat on the layout it becomes unstable
or poor power out.  Getting them to as high as 70mhz was not all
that hard if you pay attention to input and output impedance
they must be low for stability and reasonable power.

The 8 IRF510s are cheap but the total system is not cheap as you still
need a big heatsink (130mm by 130mm with 40mm fins  and a  fan) , TR
switching that can handle the power, and a package to put it all in. 
Cheap 28 or 48 volt switching  power supplies are not a solution as
often they are way to noisy on receive.

Things to consider 100W at 12V is about the limit using the right parts.
However the relays now have to be good for at least 5A and 100V
at the output and the input they can be fairly light.  With higher power
higher currents and voltage are the expected thing and parts like
#12 wire, 500V silver mica or ATC 800B are the required parts.

High power (more than 20 or so watts) tends to be expensive and
getting a reliable amp is never trivial task.

Allison

Re: Compliance Summary - other radios

iz oos
 

The KL203 senses the RF and less than 1w average power is needed. That is why it works as is with a softrock in AM FM and likely in CW. In SSB the average power is far less as in most transceivers unless a mic compressor is used. A simple mod I believe is simply to increase a little bit the picking of RF at the RX input of the KL203. The KL203 uses a 500V 8.2pf at C1. I would add another 8.2pf in parallel at C1. If you use the KL203 with 1w you may use also a non 500V cap, any will work.


Il 12/set/2019 20:14, "Sajid Rahum via Groups.Io" <zs735=yahoo.com@groups.io> ha scritto:
Hi Allison, i did get the prebuilt band pass filter from ebay.  Wondering if you have any suggestions to mod the KL-203 as well as how to mod it to be more sensistive to lower power e.g. from softrock <1w; I am able to trigger AM but not via SSB.

Re: Good news...I did NOT blow up my uBitX #ubitx-help #ubitx

Gwen Patton
 

I finally found it. What threw me was that you have to turn on Setup mode, then dial PAST "Exit Menu" to find the select for the key type. Got it working! Thanks, Curt!

73,
Gwen, NG3P

Re: Amplifier Talk- Communications Concepts

ajparent1/KB1GMX
 

Farhan,

Still around and busy.

Check out OZ1PIFs work.  I've run one section of that a 4x4 parallel push pull
on 6M to over 200W.  The yabut is you need 28V power at 15A!  At 12V that
doesn't work well.  The up side is to get that power not much drive is needed
and its easy to over drive it 5-6W was enough.  Its remarkably tough as I
haven't fried it.  The IMD is only OK.  However a really good and heavy built
low pass is needed as the first one with #18 air wound coils heated too much,
#14 wire solved that along with 500V metal clamp mica caps.

A pair of IRF510s can do 40-50w easy at 28V with 1-2W of drive. 
Parallel parts are harder as then you have parallel paths for
RF current to balance.  Cheat on the layout it becomes unstable
or poor power out.  Getting them to as high as 70mhz was not all
that hard if you pay attention to input and output impedance
they must be low for stability and reasonable power.

The 8 IRF510s are cheap but the total system is not cheap as you still
need a big heatsink (130mm by 130mm with 40mm fins  and a  fan) , TR
switching that can handle the power, and a package to put it all in. 
Cheap 28 or 48 volt switching  power supplies are not a solution as
often they are way to noisy on receive.

Things to consider 100W at 12V is about the limit using the right parts.
However the relays now have to be good for at least 5A and 100V
at the output and the input they can be fairly light.  With higher power
higher currents and voltage are the expected thing and parts like
#12 wire, 500V silver mica or ATC 800B are the required parts.

High power (more than 20 or so watts) tends to be expensive and
getting a reliable amp is never trivial task.

Allison

Re: Amplifier Talk- Communications Concepts

Ashhar Farhan
 

Allison,
Glad to see you pitch in. How has your experience with the paralleled IRF510s been? You managed to push them to 50 Mhz.

On Sun 15 Sep, 2019, 3:43 AM ajparent1/KB1GMX, <kb1gmx@...> wrote:
OK, staring from a point of experience...

First serious and decent amps in the 100W and up class even if home built will
cost not less that 2-5$/watt.  There are big metal parts and expensive transistors
in many.

Most of the cheap "70W" ebay amps have not been seen as working, for long. 
They are still in need of box, likely a real heatsink (adequately sized), low pass
filters and plenty of spare Mosfets and some do not work at all wall above 20M. 
Caveat emptor.

I have built many of the EB series of amplifiers and they are good stable designs that 
generally perform to the limits of the devices used.  Comments like "CB amps" are
generally meaningless and better avoided.  I have seen those apnotes applied
to CB and some are junk and a few were well done.  Quality is often a builder
thing rather than application.  All of the amp modules require a Low pass filter(s) 
and will be likely switched with relays or mechanically.

One last thing what you put in had better be good as 10x that will reflect
all of the flaws in you signal and more people will hear them and comment.
if that is not clear, garbage in, means garbage out.

The biggest issue for those amps are the transistors for them are scarce and often 
very expensive.  I built them as I already had the devices and last look MRF454s
are over 100$ a pair for real ones.

EB63, basic simple amp, the down side is the diode current alone will be high
and that establishes the bias.  Efficiency when built right is over 50% however
at 160M or over 10M the design is not optimal, that's hard to do over a decade
of frequency range.  However with a good low pass filter and clean input the
result is excellent but the transistors used are costly and it can be intolerent
[unstable] of random substitutions. 

AN762  is a later design that uses a 723 voltage regulator to do a precision bias 
and that is an improvement.  The deal is its excellent and not a simple build
plus the devices are near extinct, unless treasure is expended.  Most will
choke at the cost of the machined copper heat spreader alone.

An779 20W amplifer for a SSB transceiver, excellent amp with good efficiency
and low IMD  output.

AN593 amplifier for 160W (28V use) and a version for 12V that does about 80W
SSB and its a good design but one has to pay attention to the mechanical details
or cooling suffers and for 12V use the power is limited.  Since it has the driver is
part of the design its not suited for more than a fraction of a watt input.  For the
80w (13.8V) version max power in would be around 125mW.  Both versions when
correctly adjusted offer very good IMD.  I've built the 28V version.

Others built include AN791 using MRF247 for 80W at 2m. and the datasheet  MRF492
circuit with bias for 6M and near 100W output.  MRF140 28V 160W amp for 6M,
MRF174 for 2M at 150W, and a utv8100B amp for 60W (with 5W FT817 drive) at 432.

For VHF and UHF I've built far more but there I do use more power but at HF 
I tend to build to the 4-5W level and rely on either my 100W radio if more is
needed or one of several amps that include the EB63, Wa2EBY, and a
design that is similar to the EB63 with active bias.


Allison

Re: Good news...I did NOT blow up my uBitX #ubitx-help #ubitx

Curt
 

Gwen

Look again, I remember a menu setting in the stock firmware to designate using a paddle. I remember a few have fiddled some with those resistor values. Perhaps also check the entire path resistance,  after finding the setting.

Curt

Re: Good news...I did NOT blow up my uBitX #ubitx-help #ubitx

Gwen Patton
 

Ok, I've replaced the BNC with an SO-239, and that is working a lot better. CW, though, is a problem. I had originally wired it for straight key, but decided to try wiring it for paddles instead. I added the 2.2k and 10k resistors, put them in the line as shown in the schematic, and connected them to the key socket. (I use W0EB's little breakout boards for this. Much easier to get at the thing.) Problem is, I STILL don't have paddle functionality. It's only operating in straight key mode.

I looked through everything, ran through the menus, and didn't find a place to change the hand key/paddle mode -- I gather that's in a different firmware set -- but I thought that it would work automatically once the voltage divider was in place. It's still only working with the sleeve connection for dah. I need to open it BACK up and start chasing things with the ol' multimeter, but if anyone can think of something specific to check, I'd appreciate it.

This is a v3 board, no mods. I hadn't gotten around to modifying anything since I thought I'd blown it up. If I MUST, I can operate it with a straight key, and maybe even a Cootie, but it seems very squirrelly with a Cootie -- noisy, lousy contact, that sort of thing, even right after cleaning the contacts. I hit them with Deoxit regularly and pull a piece of paper through the contacts to take off any corrosion or tarnish.

73,
Gwen, NG3P
Who has to stop fiddling with gear and practice CW more...L2 class on Monday!

Re: Amplifier Talk- Communications Concepts

ajparent1/KB1GMX
 

OK, staring from a point of experience...

First serious and decent amps in the 100W and up class even if home built will
cost not less that 2-5$/watt.  There are big metal parts and expensive transistors
in many.

Most of the cheap "70W" ebay amps have not been seen as working, for long. 
They are still in need of box, likely a real heatsink (adequately sized), low pass
filters and plenty of spare Mosfets and some do not work at all wall above 20M. 
Caveat emptor.

I have built many of the EB series of amplifiers and they are good stable designs that 
generally perform to the limits of the devices used.  Comments like "CB amps" are
generally meaningless and better avoided.  I have seen those apnotes applied
to CB and some are junk and a few were well done.  Quality is often a builder
thing rather than application.  All of the amp modules require a Low pass filter(s) 
and will be likely switched with relays or mechanically.

One last thing what you put in had better be good as 10x that will reflect
all of the flaws in you signal and more people will hear them and comment.
if that is not clear, garbage in, means garbage out.

The biggest issue for those amps are the transistors for them are scarce and often 
very expensive.  I built them as I already had the devices and last look MRF454s
are over 100$ a pair for real ones.

EB63, basic simple amp, the down side is the diode current alone will be high
and that establishes the bias.  Efficiency when built right is over 50% however
at 160M or over 10M the design is not optimal, that's hard to do over a decade
of frequency range.  However with a good low pass filter and clean input the
result is excellent but the transistors used are costly and it can be intolerent
[unstable] of random substitutions. 

AN762  is a later design that uses a 723 voltage regulator to do a precision bias 
and that is an improvement.  The deal is its excellent and not a simple build
plus the devices are near extinct, unless treasure is expended.  Most will
choke at the cost of the machined copper heat spreader alone.

An779 20W amplifer for a SSB transceiver, excellent amp with good efficiency
and low IMD  output.

AN593 amplifier for 160W (28V use) and a version for 12V that does about 80W
SSB and its a good design but one has to pay attention to the mechanical details
or cooling suffers and for 12V use the power is limited.  Since it has the driver is
part of the design its not suited for more than a fraction of a watt input.  For the
80w (13.8V) version max power in would be around 125mW.  Both versions when
correctly adjusted offer very good IMD.  I've built the 28V version.

Others built include AN791 using MRF247 for 80W at 2m. and the datasheet  MRF492
circuit with bias for 6M and near 100W output.  MRF140 28V 160W amp for 6M,
MRF174 for 2M at 150W, and a utv8100B amp for 60W (with 5W FT817 drive) at 432.

For VHF and UHF I've built far more but there I do use more power but at HF 
I tend to build to the 4-5W level and rely on either my 100W radio if more is
needed or one of several amps that include the EB63, Wa2EBY, and a
design that is similar to the EB63 with active bias.


Allison

Re: Compliance Summary - other radios

Curt
 

Bill

On the Dentron, see if it uses a narrowband matching circuit, although that would also result in output power varying appreciably across the band. If you have a nearby RBN listener as I do, it may let you preceive the 40m harmonic level. My local RBN showed a simultaneous 14 MHz output when I used my hw16 on 15m, that I successfully adjusted. That's a sure problem feeding my triband yagi.

The nice kit being sold by N8DAH nicely addresses ubitx harmonics, last I heard in every tested ubitx by our club. It does not cure ssb upper band spurious on 15, 12 and 10m. (I am skeptical whether arrl lab knew to look for these in v5 testing).

Those single and few band rigs can incorporate narrower filters, making compliance easier.

Curt

Re: Amplifier Talk- Communications Concepts

John Seboldt K0JD
 

I have the other similar amp, AN762, that I got in the late 90's. http://www.communication-concepts.com/an762-140/ I have the amp built up and mounted on a monster heat sink, with a supporting case ready, and just have to craft filters and bandswitching. A kit for filters is almost done - https://hfprojects2.com/shop?olsPage=products%2Flpf-140-r1-low-pass-filter .

As usual, takes a while to finish multiple things....
John K0JD
Milwaukee, WI

On 9/12/2019 21:14, Jeffrey Benedict wrote:

I see that there has been a little bit of talk about amplifiers for ubitx.  Motorola published amplifier designs which used their transistors a few years ago and a company named Communications Concepts packaged many of them into kits with boards and parts- as much or as little as you want.  These are not "kits" as in Elecraft or Heathkits or even ubitx.  You really have to be able to go it alone with no one to hold your hand.

One that might fit the needs of the ubitx user is:

http://www.communication-concepts.com/eb63a-140w-hf-amplifier/

It takes 1-5 watts and makes as much as 140 watts out.  They have the parts listed and you can buy everything except things like cases from them.  The website is kind of cryptic I think to keep the "good buddies" from finding and building high power amps for their See Bees.  But, poke around and you will find amps of varying power and type as well as the parts to build them.  The Motorola documentation is there also.

eHam has some reviews of amplifiers built with information and parts from this site.

73

Jeff
--
Jeff, K7AIL  CN87

raoul@...

Re: Amplifier Talk- Communications Concepts

Martin KM6TCD
 

Thanks for the feedback. What about the kenwood 440s? What's its reputation?
 
Sent: Saturday, September 14, 2019 at 12:14 PM
From: "iz oos" <and2oosiz2@...>
To: BITX20@groups.io
Subject: Re: [BITX20] Amplifier Talk- Communications Concepts

The KL203 is a tabu in the ham community. Don't even think to add in parallel or replace C14 with a 500V 1000pf.

 
Il 13/set/2019 19:18, "Sajid Rahum via Groups.Io" <zs735=yahoo.com@groups.io> ha scritto:
Well Ashar

I plugged KL203 and not bad.  Not the best but works.  I need to mod KL203 to expand the power range; on 20m, it was good no issues.

Sajid

 

 

Re: Amplifier Talk- Communications Concepts

Gordon Gibby
 

Asher, the 811A amp that I built when I was a kid used more like 2000 V;   In the coming year I hope to refurbish it. 


On Sep 13, 2019, at 13:18, Sajid Rahum via Groups.Io <zs735@...> wrote:

EXTERNAL EMAIL: Exercise caution with links and attachments.


Well Ashar

I plugged KL203 and not bad.  Not the best but works.  I need to mod KL203 to expand the power range; on 20m, it was good no issues.

Sajid