Thanks Raj, very much appreciated! I will have to do this mod then which does not jeopardise the output power!
Il 10/ott/2018 09:06, "Raj vu2zap" < rajendrakumargg@...> ha scritto:
I found good reduction of spurs with the following mods:
1. Replace L5 with an SMD inductor 680nH or 681, mount at right angles to old toroid
2. Replace L7 as above.
The 45MHz filter is not required and you get almost the same power out as stock boards.
If you ALSO have 45MHz the spurs get further reduced by a little but loss of output power.
I used what I remember buying Murata inductors 1206 size.
Feed back will be appreciated.
With Mikes W0MNE relay fix and this mod will have the uBitxv3 and v4 boards kosher. The relays
have their contacts below and close to ground plane and I suspect thats is what fixes
the harmonics. I have not tried it but ordered some try after a few weeks when I get back
to shack again.
Cheers
--
Raj, vu2zap
Bengaluru, South India.
|
Re: Purchase of uBitx on hold until?
I only just noticed it after I posted
my reply to Iz, but your mod is now up on the website!
A very simple fix, albeit requiring the ordering of surface mount
parts ...? The question is why does it work to reduce the spurs?
Mike
On 10/10/18 8:22 PM, Raj vu2zap wrote:
Mike, see my SIMPLER spur fix without loss of Po!
Tested on two boards here..
Raj
At 10-10-18, you wrote:
Iz
Spurs news item:? ??
Just 3 parts and you will have that one licked.? ?? However, it
may
just be an expensive way of introducing -6dB of gain!
Mike
On 10/10/18 7:56 PM, iz oos wrote:
Mike, what are the three parts to resolve spurs? I might have
missed
something.
Il 10/ott/2018 08:38, "Mike Woods"
<mhwoods@...>
ha
scritto:
- Eliott
- The latest version of the uBITx is the v4, which doesn't
have an
audio chip at all (it has discrete transistors).??
- The v4 board MAY have audio issues ... a small
proportion of owners
have experienced audio distortion.?? There is a known fix
for this
issue and the fix is documented on
.??
The audio also has a bit
lower output than the v3 board.
- You discuss the IMD issue, but this doesn't appear to
affect most
users in practice.? ?? It may result in some splatter if
you are
over-driving the audio, but really can't be considered a
major impediment
to a purchaser.??
- There are several other issues (see
for a summary
of pros and cons).
- If you don't want to modify the board to fix issues that
really
matter (harmonics - the most substantial mod that is
required), spurs
(requires 3 parts), and to add an AGC (multiple parts)
then I suggest you
don't bother buying the kit.? ?? You may have to wait a
while to see
a further upgrade from HF Signals though (if ever)! If you
don't mind
spending a bit of time having fun making these changes,
then go for
it!?? Lots of us out there are having fun.
- 73
- Mike ZL1AXG
- ??
- On 9/10/18 6:26 AM, Eliot Ricciardelli via Groups.Io
wrote:
- I am specifically referring to the current rev of
the uBitx.
Specifically - the audio chip issue and the IMD issue.
You stated all of
yours are in spec and didn't mention any component
issues so I assume you
have none. That is helpful, thank you.
- --
- Mike Woods
- mhwoods@...
--
Mike Woods
mhwoods@...
|
Re: Purchase of uBitx on hold until?
Mike, see my SIMPLER spur fix without loss of Po!
Tested on two boards here..
Raj
At 10-10-18, you wrote:
toggle quoted message
Show quoted text
Iz
Spurs news item:? ??
Just 3 parts and you will have that one licked.? ?? However, it may
just be an expensive way of introducing -6dB of gain!
Mike
On 10/10/18 7:56 PM, iz oos wrote:
Mike, what are the three parts to resolve spurs? I might have missed
something.
Il 10/ott/2018 08:38, "Mike Woods"
<mhwoods@...> ha
scritto:
- Eliott
- The latest version of the uBITx is the v4, which doesn't have an
audio chip at all (it has discrete transistors).??
- The v4 board MAY have audio issues ... a small proportion of owners
have experienced audio distortion.?? There is a known fix for this
issue and the fix is documented on
.?? The audio also has a bit
lower output than the v3 board.
- You discuss the IMD issue, but this doesn't appear to affect most
users in practice.? ?? It may result in some splatter if you are
over-driving the audio, but really can't be considered a major impediment
to a purchaser.??
- There are several other issues (see
for a summary
of pros and cons).
- If you don't want to modify the board to fix issues that really
matter (harmonics - the most substantial mod that is required), spurs
(requires 3 parts), and to add an AGC (multiple parts) then I suggest you
don't bother buying the kit.? ?? You may have to wait a while to see
a further upgrade from HF Signals though (if ever)! If you don't mind
spending a bit of time having fun making these changes, then go for
it!?? Lots of us out there are having fun.
- 73
- Mike ZL1AXG
- ??
- On 9/10/18 6:26 AM, Eliot Ricciardelli via Groups.Io wrote:
- I am specifically referring to the current rev of the uBitx.
Specifically - the audio chip issue and the IMD issue. You stated all of
yours are in spec and didn't mention any component issues so I assume you
have none. That is helpful, thank you.
- --
- Mike Woods
- mhwoods@...
--
Mike Woods
mhwoods@...
|
Re: Purchase of uBitx on hold until?
Iz
Spurs news item:??
Just 3 parts and you will have that one licked.?? However, it may
just be an expensive way of introducing -6dB of gain!
Mike
On 10/10/18 7:56 PM, iz oos wrote:
Mike, what are the three parts to resolve spurs? I might have
missed something.
|
I found good reduction of spurs with the following mods:
1. Replace L5 with an SMD inductor 680nH or 681, mount at right angles to old toroid
2. Replace L7 as above.
The 45MHz filter is not required and you get almost the same power out as stock boards.
If you ALSO have 45MHz the spurs get further reduced by a little but loss of output power.
I used what I remember buying Murata inductors 1206 size.
Feed back will be appreciated.
With Mikes W0MNE relay fix and this mod will have the uBitxv3 and v4 boards kosher. The relays
have their contacts below and close to ground plane and I suspect thats is what fixes
the harmonics. I have not tried it but ordered some try after a few weeks when I get back
to shack again.
Cheers
--
Raj, vu2zap
Bengaluru, South India.
|
Re: Purchase of uBitx on hold until?
Mike, what are the three parts to resolve spurs? I might have missed something.
Il 10/ott/2018 08:38, "Mike Woods" < mhwoods@...> ha scritto:
Eliott
The latest version of the uBITx is the v4, which doesn't have an
audio chip at all (it has discrete transistors).?
The v4 board MAY have audio issues ... a small proportion of
owners have experienced audio distortion.? There is a known fix
for this issue and the fix is documented on .? The audio
also has a bit lower output than the v3 board.
You discuss the IMD issue, but this doesn't appear to affect most
users in practice.?? It may result in some splatter if you are
over-driving the audio, but really can't be considered a major
impediment to a purchaser.?
There are several other issues (see
for a
summary of pros and cons).
If you don't want to modify the board to fix issues that really
matter (harmonics - the most substantial mod that is required),
spurs (requires 3 parts), and to add an AGC (multiple parts) then
I suggest you don't bother buying the kit.?? You may have to wait
a while to see a further upgrade from HF Signals though (if ever)!
If you don't mind spending a bit of time having fun making these
changes, then go for it!? Lots of us out there are having fun.
73
Mike ZL1AXG
?
On 9/10/18 6:26 AM, Eliot Ricciardelli via Groups.Io wrote:
I am specifically referring to the current rev of the uBitx.
Specifically - the audio chip issue and the IMD issue. You stated
all of yours are in spec and didn't mention any component issues
so I assume you have none. That is helpful, thank you.
|
Re: Purchase of uBitx on hold until?
Eliott
The latest version of the uBITx is the v4, which doesn't have an
audio chip at all (it has discrete transistors).?
The v4 board MAY have audio issues ... a small proportion of
owners have experienced audio distortion.? There is a known fix
for this issue and the fix is documented on ubitx.net.? The audio
also has a bit lower output than the v3 board.
You discuss the IMD issue, but this doesn't appear to affect most
users in practice.?? It may result in some splatter if you are
over-driving the audio, but really can't be considered a major
impediment to a purchaser.?
There are several other issues (see
for a
summary of pros and cons).
If you don't want to modify the board to fix issues that really
matter (harmonics - the most substantial mod that is required),
spurs (requires 3 parts), and to add an AGC (multiple parts) then
I suggest you don't bother buying the kit.?? You may have to wait
a while to see a further upgrade from HF Signals though (if ever)!
If you don't mind spending a bit of time having fun making these
changes, then go for it!? Lots of us out there are having fun.
73
Mike ZL1AXG ubitx.net
?
On 9/10/18 6:26 AM, Eliot Ricciardelli via Groups.Io wrote:
I am specifically referring to the current rev of the uBitx.
Specifically - the audio chip issue and the IMD issue. You stated
all of yours are in spec and didn't mention any component issues
so I assume you have none. That is helpful, thank you.
|
Re: QSX 10W HF Linear PA kit
this is a very well designed amp. the extensive use of feedback helps preserve linearity. we don't get the BS170 transistors in india for some strange reason. i might as well just order this to play with it.
- f
OK 13db gain for the final stage. As many of us have 0.7-1w qrps what is the (approximate) absolute maximum rating for the input power of the final stage without going nonlinear? 0.5w or more?
|
Re: Harmonics and Relay Replacement
The contacts are below, close to the ground plane possible less coupling
and short so less inductance.
Raj
Pic: from the net.
At 09-10-18, you wrote:
Pictures are always nice,
Glenn.
Since most of these larger relays have the long armatures which run
parallel to the coil and the coil is not shielded? (right
?), there would be RF coupling between the armature and the coil. It
would also seem that, for a given voltage, higher current relays would
imply larger wire, fewer turns, and less inductance for Port to Port
coupling (right ?).
Can't do much to reduce inner relay coupling but you could reduce relay
to relay coupling by using a small RF choke (100uH) in the both existing
relay coil leads. I like the WireWound ones from Bourns (CM322522-101K1).
73 Kees K5BCQ
|
Re: QSX 10W HF Linear PA kit
OK 13db gain for the final stage. As many of us have 0.7-1w qrps what is the (approximate) absolute maximum rating for the input power of the final stage without going nonlinear? 0.5w or more?
Il 09/ott/2018 21:13, "Hans Summers" < hans.summers@...> ha scritto:
> I have just seen it on your website.? > Really nice. How much gain does it? > have if we exclude the first stage?
Well you know how these things are, every time you vary one thing, something else changes... so it's hard to be totally precise. But approximately the gain is split equally between the two stages. 13dB each.
> This kit won¡¯t make the spur and? > bandpass problems of the uBITx? > go away.? Period.? Those problems? > occur in the early stages of the? > uBITx.? To the contrary it has the? > opportunity to make them worse? > since the gain of the amp is flat? > from 3-20 MHz? It may, however? > be a nice replacement for the final? > two stages in the uBITx if you want? > to maintain a fairly flat gain in? > those two stages.? That¡¯s all.
Yes, exactly what I said in my initial post on this topic. The uBITX has many problems (or depending on your viewpoint, challenges, minor issues, what you get in an experimenter's radio etc etc.). This amp kit fixed at best, the final two stages only. Garbage in, garbage out...
What it does show is:
1) Good PCB layout, short traces and short leads work wonders
2) IRF510's are good for the job - it isn't necessary to spend $$ on fancy RD15HVF1 or its brothers and sisters or uncles and cousins...
3) Surface mount components aren't necessary to assure stability either.
Note... even Chinese IRF510's do a great job - once you find the right and reliable supplier. All Ferrites in the kit are sourced from Diz at , I'm a highly satisfied (and not insignificant) customer!
73 Hans G0UPL? ?
|
Should be easy enough to replace Q13 with a through-hole 2n3904.
And should work fine.
You need to first remove the old surface mount MMBT3904 at Q13.
Heat up the pin that's alone along one side with a soldering iron and lift that pin off the board a little bit with a knife.
Then do the same with the other two pins.
Solder the leads of your new 2n3904 to the appropriate ends of R132 and R134.
Jerry
I suggest you first remove the old su
toggle quoted message
Show quoted text
On Tue, Oct 9, 2018 at 09:16 PM, <craigmclean@...> wrote:
It looks like I've damaged Q13 on my Bitx40 v3 board, this is annoying because the diodes for the protection modification are sitting on my bench not installed.? I happen to have some 2N3904 through hole parts sitting here.? Is there a good quality way to substitute that in, or should I order a new SMT version of that transistor?? I looked around and say lots of people who said they need to replace it, but none mentioned how.
|
Re: Harmonics and Relay Replacement
Nice analysis. ?Could you please try with smd inductor 100uH, Please !! regards vu3zmv
 
Sure is fun with good test equipment........ I deleted the last picture because it may cause confusion.
#1 The first plot is the coupling between the Armature and the coil for a small 10 pin Omron relay.
#2 The second plot is the coupling between the Armature and the coil for a larger 16 pin HFD27 relay. You can see that it is about 7dB worse than the Omron.
#3 (deleted) I tried various RF chokes (1uH to 100uH) which improves the HFD27 relay plots but not at the low end because of the self resonance of the inductor. The Bourns 100uH inductor I was using has a self resonance at about 10MHz. This requires some more study and head scratching.
73 Kees K5BCQ
|
Hello.
It looks like I've damaged Q13 on my Bitx40 v3 board, this is annoying because the diodes for the protection modification are sitting on my bench not installed.? I happen to have some 2N3904 through hole parts sitting here.? Is there a good quality way to substitute that in, or should I order a new SMT version of that transistor?? I looked around and say lots of people who said they need to replace it, but none mentioned how.
I suspect I blew Q13 because I used a W6LVP receive loop on the radio and it has a preamp on it.
|
Re: Harmonics and Relay Replacement
  Sure is fun with good test equipment........ I deleted the last picture because it may cause confusion. #1 The first plot is the coupling between the Armature and the coil for a small 10 pin Omron relay. #2 The second plot is the coupling between the Armature and the coil for a larger 16 pin HFD27 relay. You can see that it is about 7dB worse than the Omron. #3 (deleted) I tried various RF chokes (1uH to 100uH) which improves the HFD27 relay plots but not at the low end because of the self resonance of the inductor. The Bourns 100uH inductor I was using has a self resonance at about 10MHz. This requires some more study and head scratching. 73 Kees K5BCQ
|
Re: QSX 10W HF Linear PA kit
Just one more comment to Hans.
I have order a kit, going to build a monobander 10/11m SSB rig.
But, I am just reading through the PA's manual, and really, your manuals are second to none!?
Absolutely superb detailed instructions, very clear step by step.
Well done again.
73 NIck VK4PP
|
Re: QSX 10W HF Linear PA kit
Hi All.
Just remembered, the GQRP SPRAT magazine recently had an article for a +-30db amp based on the MMBTH10 if I remember correctly.
It used 4 of them. Ill see if i can find more details to share
I think this may make a good pre-driver for the QSX amp?
73 Nick.
|
Re: QSX 10W HF Linear PA kit
> I have just seen it on your website.? > Really nice. How much gain does it? > have if we exclude the first stage?
Well you know how these things are, every time you vary one thing, something else changes... so it's hard to be totally precise. But approximately the gain is split equally between the two stages. 13dB each.
> This kit won¡¯t make the spur and? > bandpass problems of the uBITx? > go away.? Period.? Those problems? > occur in the early stages of the? > uBITx.? To the contrary it has the? > opportunity to make them worse? > since the gain of the amp is flat? > from 3-20 MHz? It may, however? > be a nice replacement for the final? > two stages in the uBITx if you want? > to maintain a fairly flat gain in? > those two stages.? That¡¯s all.
Yes, exactly what I said in my initial post on this topic. The uBITX has many problems (or depending on your viewpoint, challenges, minor issues, what you get in an experimenter's radio etc etc.). This amp kit fixed at best, the final two stages only. Garbage in, garbage out...
What it does show is:
1) Good PCB layout, short traces and short leads work wonders
2) IRF510's are good for the job - it isn't necessary to spend $$ on fancy RD15HVF1 or its brothers and sisters or uncles and cousins...
3) Surface mount components aren't necessary to assure stability either.
Note... even Chinese IRF510's do a great job - once you find the right and reliable supplier. All Ferrites in the kit are sourced from Diz at , I'm a highly satisfied (and not insignificant) customer!
73 Hans G0UPL? ?
|
Re: QSX 10W HF Linear PA kit
Jerry,
I agree that we need more than one MMIC for the TX gain stages.
My initial idea was/is? to replace the "famous" Q90 with a three
transistor W7ZOI amp (gain = 15 dB) may be using even BFR106
instead of the MMBT3904.
The output power of this stage may be limited to about +3 dBm as
W7ZOI?? stated when using this amp in bidirectional mode. used in
a single direction the linear oputput may be higher.?? The next
stage has to deliver the necessary +14 dBm or even a bit more for
"headroom") -- for this stage a MMIC could be one choice or
another suitable "medium power transitor" with a high ft.?
Henning
Am 09.10.2018 um 20:06 schrieb Jerry
Gaffke via Groups.Io:
toggle quoted message
Show quoted text
First off, the uBitx as is does pretty well on 80/40/20 meters.
Power drops off on the stock uBitx as we go up to 15 and 10
meters.
There's 6 months worth of discussion in this forum about how
best to?
get power up to where it should be on those high bands.
Tough to do, most attempts failed when modifying the existing
uBitx power amp.
Grafting the QSX amp into the uBitx could mostly solve that.
Could also solve issues of power amp energy coupling back into
the IF amps,
especially if the power amp is off in it's own box.
But the current signal levels in the IF amps and mixers create
trouble with spurs
on those upper bands.? Not too much point in going to the QSX
power amp unless
we clean that stuff up first.? And while we're at it, improve
IMD and carrier leakage
in those IF amps and mixers as well.
?
If we assume we increase local oscillator CLK2 into the first
mixer at D1,D2 up to 7dBm,
then the maximum signal into it from the 45mhz IF during
transmit should be at least 10dB down
from that, or about -3dBm.? The mixer probably has a loss of
around 6dB, and the 30mhz LPF
might lose another dB.? So if we replace everything from Q90 on
out to the IRF510's with a
new power amp, that new amp will see a max of -10dBm, or 0.1mW
going in.
This new QSX amp has 26 dB of gain for 10W out (where 10W out is
+40dBm),
so needs 40dBm-26db = 14dBm going into the QSX amp (as Henning
has said).
We need at least an additional 24 dB of gain to go from -10 dBm
out of the 30mhz LPF
to +14dBm into the QSX amp.? That could easily be done with two
MMIC stages,
and there are many such MMIC's capable of delivering 14dBm of
power to the QSX amp.
Some extra gain in those two MMIC's would be good so we?can keep
the signal through
the mixers even lower, and have some headroom for an adjustment
such as RV1 of the uBitx.
Mouser 630-ADA-4743-TR1G
If you plan to bring the power up to 20W by boosting the supply
voltage into the QSX amp,
then you will need another 3dB of power going in, so
14dBm+3dB=17dBm into the QSX amp.
And at 20W, you would want heavier transmit LPF's than the ones
provided on the uBitx.
Also, it may be a good idea to have a 3dB attenuator between the
MMIC's and the QSX amp
to keep it stable.
It will be interesting to see how clean we can make the uBitx as
an exciter.
May need better transistors in the 45mhz stage, certainly want
less gain
on the two transmit side IF amps.? Want 7dBm of drive from the
local oscillators.
Perhaps the transformers in the mixers are not ideal, especially
at 45mhz.
Raj has made considerable progress in sorting this some of this
out.
?
I've got a QSX amp on order.?
Looking forward to playing with it.
But the uBitx has other issues to fix before we make use of the
QSX amp
to increase power out on those upper bands.
Jerry, KE7ER
On Tue, Oct 9, 2018 at 07:54 AM, Henning Weddig wrote:
Hans,
I just ordered one of Your 10 W PA kits and quickly read over
the assembly instruction.
Concerning the UBITX: the PA delivers 26 dB of gain, so for
10 W output the input power for the PA is +40 dBm - 26 dB =
+14 dBm This power can be easily achieved with only one MMIC
e.g. one of the GALI amps--- or a discrete verions (BS170)?
As You also offer LPF kits, the problems of the uBITX can be
obsolete, but requires extra space for these extra boards.
One thing I m missing are the information about the P1dB
pointz ( 40 dBm)? and IMD performance.?
Henning Weddig
DK5LV
|
You could update the firmware, 1.1 is out.
A few things. Are you using a Nextion, have you built the extra stuff necessary (ie, another arduino nano?).
(I have a question about that, there's got to be a script/hex specifically for the 2nd nano, right?)
I have yet to put my uBitx all together, getting everything together first (Nextion 3.2")
But I think you need to use Memory Manager in order to get the s-meter working.
Or I could be completely off-base, as I'm very new to all this.
Dave - AI6K
|
Re: Harmonics and Relay Replacement
Kees
Has anyone tried adding a 0.1 mfd across each of the relay coils, and additional 0.1 mfd to ground from various places in the DC going to these relays.? Suspicion is that some of
the unwanted coupling might be via the relay coils and connecting traces.
Arv _._
Seems like most of these larger relays have the long armatures which run parallel to the coil and the coil is not shielded??
|
Raj vu2zap
Nick VK4PP