Re: Started my uBitx build
Iz, what can I do to rectify using a 4 ohm speaker. Should I add a 4 ohm resistor in series?
toggle quoted message
Show quoted text
On Sep 19, 2018, at 2:11 PM, iz oos < and2oosiz2@...> wrote: Just connect the amplifier to the audio output from the built-in audio amp.. Only for version <=3 I wouldn't use lower than 8ohm speakers.
|
I have 7"
Like to purchase kit with all extra parts; pots, wire sockets pluga mem chip loaded.
Anything else i would take.
Alan Kessler
WB2BQK
|
Re: UBITX Q90 mod with BFR106
Glenn,
When you added the bifilar 2t choke to supply power to the PA output (vs 2x separate 60uH chokes) and a 150pF high voltage compensation capacitor across the T11 Output transformer primary, the design begins to look like many of the earlier more conventional dual MOSFET PA designs as pointed out in several previous posts. I would also bypass the power supply end of that 2t choke with 100nF, 10nF? and 1nF capacitors. You may now also find that you do not need the 2 feedback resistors and capacitors (220 ohm and 100nF) or you can reduce the feedback (larger resistor). The next step is to use RD15HV1 or RD16HHF1 MOSFETS (I know you don't agree, Allison).
By the way, increasing the 150pF compensation capacitor will raise the low (80m) end and drop the high (10m) end. Decreasing the value will do the opposite.
73 Kees K5BCQ
|
Re: JackAl System Preview
Hi Gilles:
We are working on an assembly manual that probably answers those questions. An "alpha" of the manual is attached. If questions remain, let me know.
Jack, W8TEE
On Wednesday, September 19, 2018, 12:53:53 PM EDT, F1BFU - Fr - 79 <gilles.f1bfu@...> wrote:
Hi Al & Jack
Can we tell us the hardware changes to make to a factory uBitx to get all these nice features?
Thanks again Al & Jack
73 QRO Gilles F1BFU /FR
Jack, I am also VERY interested in your board, when complete. Please add? me to the list.
On Wednesday, September 19, 2018 9:05 AM, F1BFU - Fr - 79 <gilles.f1bfu@...> wrote:
Hello Al & Jack
Very good project. I'm interested. Please add me also to buyer¡¯s?with TFT 7" option.
Paypal Invoice to gilles.f1bfu(at)?( please replace (at) by @) Very good stuff 73¡¯s Gilles ¨C F1BFU /FR
|
Re: Started my uBitx build
Just connect the amplifier to the audio output from the built-in audio amp.. Only for version <=3 I wouldn't use lower than 8ohm speakers.
Il 19/set/2018 20:04, "Daniel" < gonewiththeego@...> ha scritto: iz oos, I will try find an 8 ohm speaker. If this is not working as expected, do you think I have to completely bypass the built-in audio amplifier and use an another amplifier or just connect the amplifier to the audio output from the built-in audio amp ?
|
Re: Started my uBitx build
iz oos, I will try find an 8 ohm speaker. If this is not working as expected, do you think I have to completely bypass the built-in audio amplifier and use an another amplifier or just connect the amplifier to the audio output from the built-in audio amp ?
|
Re: Started my uBitx build
Thanks Joe, that's the mic from the surveilance camera? My knowledge is as well on the first floor but I'm not affraid to dig farther.
|
Re: UBITX Q90 mod with BFR106
Broken "ENTER" key on his keyboard, or some other problem?
_._
On Wed, Sep 19, 2018 at 10:56 AM kg9rb via Groups.Io <kg9rb= [email protected]> wrote: hey everyone,
ka9koj here.
ive been reading the posts on the harmonics and maybe we should just isolate the rf signal prior to any preamplification.break the flow before amplification, and insert some filters. ? just a thought.the 2n3904s and 2n2222 have been the backbone for all ham transceivers for along time. granted , the circuits may be either overdrivien or laid out in such a way to promote imd and harmonics to no fault of anyone. i installed the 45 mhz filter i bought off ebay and seems to do a decent job. the harmonics, short of rebuilding the rig, im installing external filters. just like the good old days. even today this practice will clean up 98 percent of harmonics if a proper filter for a given band is used.The term spurious emissions refers to any signal which comes out of a transmitter other than the wanted signal. In modern equipment there are three main types of spurious emissions: harmonics ,out of band mixer products which are not fully suppressed and leakage from the local oscillator and other systems within the transmitter.could be the combination of the chosen if and local oscillator is causing this problem ,maybe some shielding, and change the mixer circuit ,etc.short of redesigning this radio, im going to use external filters and turn the drive down a little so if any circuits are being overdriven , it will cut down on the distortion being passed thru.just a thought. But, i also think ashar has done an incredible job offering this radio kit for the price it is. incredible. i am loving my ubitx alot.the receive is great and the audio is crisp.granted its not an elecraft, or a ft857, or flex1500. this radio was built by someone who loves our community of ham radio. making the opportunity of getting on the air possible with only a small cash output. i have also heard and seen newer high dollar rigs put out alot of garbage. every go to field day? take a good communications receiver with you and a scanner for higher vhf/uhf frequencies and you will be horribly surprised to find out that those newer 1000 dollar rigs are putting out harmonics more than this little rig is doing. in fact one year i really upset several hams by suggesting they need to stop transmitting. i was quite away from the field day site and could tune in the harmonics of several high dollar rigs on the air.one was an elecraft, another was an alinco which i really like, and the icom which was bought for about 900 dollars right from the fact one was transmitting in the aircraft band and i made a recording and a video of it and showed the operator. this guy was shocked. he quit immediately but became angry ,not at me but at the dealer who sold him this high dollar harmonic generator. we checked his setup and how his rig was set on settings .perfect.this was a ham who lives in southern also going to install some either band reject or bandstop filters to help get rid of the bad ones.my setup now, is a switchable filter box with manual switch. each band has a filter. and if i dont want to transmit but just listen to shortwave or whatever i have a toggle to bypass the filters so i can listen to everything..this toggle is connected to an led with internal 9 volt battery to give me status of filter,.but short of redesigning the rig, this is my fix and the 45 mhz filter in place of r27 seems to work great. I also think its great we have a pool of technologically capable individuals who can identify and design fixes for these problems. this is what makes this fourm so great.
73s and good dxing.
ka9koj
|
Re: Started my uBitx build
I have the version 3. The TDA delivers a lot of audio. I think 4ohm is too low and probably not recommended. I have opted for a 8ohm speaker. Version 4 is totally different, if the audio is not enough you might think to tinker the audio circuit or alternatively add cheap amplified speakers.
Il 19/set/2018 19:24, "Joe Puma" < kd2nfc@...> ha scritto: Daniel the speaker I used is a 4 ohm 6watt speaker. It came from a old surround sound system made up of 4 small speakers and the sub woofer. The speaker is still in its small enclosure. It sounds decent. I had an issue where I thought my sound was weak too but I realized I had a bad antenna connection and the center pin on the BNC connector on the cable I was using. Fixed that up and it was sounding good.?
My next tasks will be to improve mic audio. I¡¯m using a dynamic mic, the Yaesu MH-31. So I have to mod the mic pre-amp circuit a little for it. Either that or mod the mic and put an electic mic in.? Other thoughts we¡¯re adding a powered mic preamp circuit. I have some high sensitivity powered mic¡¯s that are used for security cameras and surveillance. It powers up with 12v, I hooked it up to the mic path and holy cow it was so loud it picked up everything. I suppose I would have to put a potentiometer inline somewhere to back down the sensitivity but I would have to figure that out. My EE knowledge is just a speck in the universe compared to others on this group.?
Joe KD2NFC?
Joe KD2NFC? Hey! I like the way you put the uBitx in the case. Well done! I have a uBitx V4.3 which I tested few days ago. Can you tell me please what's the impedance and the power of the speaker you use? Because I barely can hear mine. I used a portable, self powered audio amplifier connected in the place of the speaker but I can say it's still under any normal expectation. On the V 4.3 there is no IC for audio. Only discrete components.?
|
On Mon, Sep 17, 2018 at 04:14 PM, David S wrote:
Signal Levels
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?RMS
? ? ? ? ? ? ? ? ?dBm? Voltage? Power
Audio? to Mod Max = -6? ? ?-3? ? 0.158? ? ?0.0005? W? Signal??
I would rather see that closer to -10db? lower than the 12mhz osc... more on that.
If we over drive the mod the the worst is we have in band (whatever the filter bandwidth is)
IMD and it may even be audible.? Usually level here is 1/6th to 1/10th the oscillator injection.
12MHz OSC? ? ? ? ? ? ? ? ? ? ? ? 4? ? ?0.354? ? 0.0025? W? OSC
First problem.? 2.5mW is low we want near 7dbm (easily twice that).
Its low because of the attenuator between 5351 and the modulator.
Modulator O/P? Loss = -6? ? -2? ? 0.178? ? 0.00063 W? Signal
That would actually be signal in - modulator (mixer) loss or about 5-6db less
or -11dbm.? This is the point where levels are important as it determines
best possible carrier to modulation.
There? is also a attenuator before the crystal filter of some 4db.? And the
filter has a loss of under 4db.? So some gain is needed but not 18+db,
I'd design for maybe 11db of gain. or pull that pre crystal filter attenuator
and use about 7db gain.??
12Mhz TLA? ? ? ?Gain? ? ?0? ? -2? ? 0.178? ? 0.00063 W? Signal
TLA?? ?is that the attenuator I just referred to?
12MHz Filter? ? ?Loss? ? -6? ? -8? ? 0.089? ? 0.00016 W? Signal
Your loss number is high.? Measured was 4db.
Where is the TIA?? that's about 18db? The feedback?
components suggest that.
57MHz OSC? ? Input? ? ? ? ? ? 4? ? ?0.354? ? 0.0025? ?W? OSC
Again not enough LO by 50%
1st Mixer I/P? ? ?Max = -6? ? ?-8? ? 0.089? ? 0.00016 W? Signal
Ip for the mixer should be about 5-7db below the lo power?
However its can fll off faster for insufficient LO.
1st Mixer O/P?Loss? -6? ? ?-14? ?0.045? ? 0.00004 W? Signal
About right on loss.
45MHZ Filter? ? Loss? -6? ? ?-20? ?0.0224? ?0.00001 W? Signal
Measured 4db again.
45MHz TLA?Gain? 12? ? ?-8? ? 0.089? ? 0.00016 W? Signal
That agrees with measured but varies all over the map due to?
variations in 3904s being used at Fmax for the gain desired.
The feedback values are for the same gain as the 12mhz amp
or about 18+db.? ?12Db make the gain marginal high.
Final OSC? ? ? ?Input? ? ? ? ? ? ?4? ? 0.354? ? 0.0025? W? ?OSC
Again low injection power.? This also lowers the intercept point.
So the overload threshold is lower.? Here we do not want to
exceed that value as spurs are a result as the filtering? after
this mixer is low pass only so difference spurs are a risk.
2nd Mixer I/P? ?Max = -6? ? ?-8? 0.089? ? 0.00016 W? Signal
Much less than -6 again... as above.
2nd Mixer O/PLoss? -6? ? ?-14? ? 0.045? ?0.00004 W? Signal
Measurement did confirm that loss.
Amp? ? ? ? ? ? ? ? Gain? 17? ? ? ?3? ? 0.316? ? 0.002? ? W? Signal
You mean Q90!? 16-17 db gain is desired and more would be good.
the problem is 3904 at 10M is at best going to do maybe 10-12db.
Its the first stage to sag with frequency.
Attenuator? ? ? ?Loss? -2? ? ? ? 1? ? 0.251? ?0.00126 W? Signal
This is RV2 and could be more of less but its at minimum
100 ohms parallel to the predriver input so it has no less than 2-3db loss
Pre Driver? ? ? ?Gain? 14? ? ? 15? ? 1.26? ? ?0.032? ? ?W? Signal
On a good day and 80M.? Bad day at 10M you are wishing.
Measured at 80M near 16db, at 10M barely 10-11.
Driver? ? ? ? ? ? ? Gain? 13? ? ? 28? ? 5.62? ? ?0.631? ? W? Signal
Same problem only worse.
Transistor that can't deliver thepower and gain across the full 3-30mhz
and a circuit that by layout, matching (transformers) and feedback
used makes it worse.? At this point we have three stages causing?
significant gain tilt.
PA? ? ? ? ? ? ? ? ? ?Gain? 12? ? ? 40? ? 22.4? ? ? ?10? ? ? ?W? Signal
Due to structure and transformers it varies.? We want 12-13db.
At 80M it can be easily? 16-18db and at 10M due to circuit its hanging
at about 12-13db but can be lower. for this stage gain issues are due
to poor matching and layout the device is doing the job.
If these figure are anyway near correct it would seem that the 12MHz TIA could be bypassed completely if the audio level is raised some..
No.? ? First the TIA are more parts and complexity than needed.? But for RX the gain could be higher
especially for the 45mhz amp!? For TX much lower for both.? IF we modify the three attenuators for?
mod and mixers we get more lo power we would like to see 7-10dbm.? The 5351 can do 7 with 1-2db
of attenuator structured to present a higher resistance to the 5351 and something near 50 ohm to the
three mixers (FYI the modulator is a mixer).? Then pull the pre 12mhz attenuator(r114, 115, 116) as
that is unneeded and more to the unused pins 1 and 6 of the transformer it saves parts and space.
The TX 12 IF must be very low gain and need not be the TIA form as two transistors can do that.
From the second mixer on out we almost have it save for the 45mhz is weak and we want more
RX gain? but TX gain can and must be lower.? That path is mixer two output? -4db for the filter
and target? -10db for the 1st mixer (45mhz to signal) at -10dbm.
Allison
|
Harmonics are an issue on all bands. There are several ways to get rid of them, the easiest using plug and play external low pass filters for each or two close bands. Spurs are not an issue on 20 and 40m bands as far as I know.
Il 19/set/2018 16:11, "Daniel" < gonewiththeego@...> ha scritto: Hi everyone! I'm not sure I totally understand what are the spurs and harmonics, I have a faint idea, anyway. What I read on the net is that are no known issues about spurs and harmonics in the 40m and 20m bands. Can some of you confirm that or not? Thank you !
|
Thank you very much, Allison. Now you made some more light in my perception about these things. So, for the moment I'll stick to the lower bands (20m, 40m) the main reason being the power of the uBitx which is dropping hard on 10m. I understood that is around 2-3 W, so for sure I can't cross the Galaxy with this output. Now it's time for me to do some research on harmonics, as you said, in the lower bands these can be the issue.?
|
Re: Started my uBitx build
Daniel the speaker I used is a 4 ohm 6watt speaker. It came from a old surround sound system made up of 4 small speakers and the sub woofer. The speaker is still in its small enclosure. It sounds decent. I had an issue where I thought my sound was weak too but I realized I had a bad antenna connection and the center pin on the BNC connector on the cable I was using. Fixed that up and it was sounding good.?
My next tasks will be to improve mic audio. I¡¯m using a dynamic mic, the Yaesu MH-31. So I have to mod the mic pre-amp circuit a little for it. Either that or mod the mic and put an electic mic in. ?Other thoughts we¡¯re adding a powered mic preamp circuit. I have some high sensitivity powered mic¡¯s that are used for security cameras and surveillance. It powers up with 12v, I hooked it up to the mic path and holy cow it was so loud it picked up everything. I suppose I would have to put a potentiometer inline somewhere to back down the sensitivity but I would have to figure that out. My EE knowledge is just a speck in the universe compared to others on this group.?
Joe KD2NFC?
Joe KD2NFC?
toggle quoted message
Show quoted text
On Sep 19, 2018, at 10:03 AM, Daniel < gonewiththeego@...> wrote: Hey! I like the way you put the uBitx in the case. Well done! I have a uBitx V4.3 which I tested few days ago. Can you tell me please what's the impedance and the power of the speaker you use? Because I barely can hear mine. I used a portable, self powered audio amplifier connected in the place of the speaker but I can say it's still under any normal expectation. On the V 4.3 there is no IC for audio. Only discrete components.?
|
Re: UBITX Q90 mod with BFR106
hey everyone,
ka9koj here.
ive been reading the posts on the harmonics and maybe we should just isolate the rf signal prior to any preamplification.break the flow before amplification, and insert some filters. ? just a thought.the 2n3904s and 2n2222 have been the backbone for all ham transceivers for along time. granted , the circuits may be either overdrivien or laid out in such a way to promote imd and harmonics to no fault of anyone. i installed the 45 mhz filter i bought off ebay and seems to do a decent job. the harmonics, short of rebuilding the rig, im installing external filters. just like the good old days. even today this practice will clean up 98 percent of harmonics if a proper filter for a given band is used.The term spurious emissions refers to any signal which comes out of a transmitter other than the wanted signal. In modern equipment there are three main types of spurious emissions: harmonics ,out of band mixer products which are not fully suppressed and leakage from the local oscillator and other systems within the transmitter.could be the combination of the chosen if and local oscillator is causing this problem ,maybe some shielding, and change the mixer circuit ,etc.short of redesigning this radio, im going to use external filters and turn the drive down a little so if any circuits are being overdriven , it will cut down on the distortion being passed thru.just a thought. But, i also think ashar has done an incredible job offering this radio kit for the price it is. incredible. i am loving my ubitx alot.the receive is great and the audio is crisp.granted its not an elecraft, or a ft857, or flex1500. this radio was built by someone who loves our community of ham radio. making the opportunity of getting on the air possible with only a small cash output. i have also heard and seen newer high dollar rigs put out alot of garbage. every go to field day? take a good communications receiver with you and a scanner for higher vhf/uhf frequencies and you will be horribly surprised to find out that those newer 1000 dollar rigs are putting out harmonics more than this little rig is doing. in fact one year i really upset several hams by suggesting they need to stop transmitting. i was quite away from the field day site and could tune in the harmonics of several high dollar rigs on the air.one was an elecraft, another was an alinco which i really like, and the icom which was bought for about 900 dollars right from the dealer.in fact one was transmitting in the aircraft band and i made a recording and a video of it and showed the operator. this guy was shocked. he quit immediately but became angry ,not at me but at the dealer who sold him this high dollar harmonic generator. we checked his setup and how his rig was set on settings .perfect.this was a ham who lives in southern indiana.im also going to install some either band reject or bandstop filters to help get rid of the bad ones.my setup now, is a switchable filter box with manual switch. each band has a filter. and if i dont want to transmit but just listen to shortwave or whatever i have a toggle to bypass the filters so i can listen to everything..this toggle is connected to an led with internal 9 volt battery to give me status of filter,.but short of redesigning the rig, this is my fix and the 45 mhz filter in place of r27 seems to work great. I also think its great we have a pool of technologically capable individuals who can identify and design fixes for these problems. this is what makes this fourm so great.
73s and good dxing.
ka9koj
|
Re: JackAl System Preview
Hi Al & Jack
Can we tell us the hardware changes to make to a factory uBitx to get all these nice features?
Thanks again Al & Jack
73 QRO Gilles F1BFU /FR
Jack, I am also VERY interested in your board, when complete. Please add? me to the list.
On Wednesday, September 19, 2018 9:05 AM, F1BFU - Fr - 79 <gilles.f1bfu@...> wrote:
Hello Al & Jack
Very good project. I'm interested. Please add me also to buyer¡¯s?with TFT 7" option.
Paypal Invoice to gilles.f1bfu(at)?(please replace (at) by @) Very good stuff 73¡¯s Gilles ¨C F1BFU /FR
|
Re: UBITX...getting to legal ???
Tim,
IMD happens anytime the slope of the gain equation for the amplifier
becomes non-linear.
Nailed it!? It is the fundamental measure of the linearity and distortion?
level of an amplifier.
For general amplifier it is the IP3 value that gets looked at.
The bottom line is for SSB amplifiers must be linear.? That explicitly means
every stage in the chain.
Allison
|
Re: uBITX schema relay K1
#ubitx
Brian, Fred, all,
THe use of K1 and 3 as in the schematic may work but the physical layout also interacts.
They are on opposing edes of the board and that interconnect for RX runs the width of
the board. It does pick up RF!
FYI the isolation of the contacts from set to set about 50db and from open contact to
wiper/other contact about 20-25db.? Contrast to the gain of the amp at about 60db.
Its a unsatisfactory arrangement and during amplifier improvement leads to oscillation.
Allison
|
Re: uBITX schema relay K1
#ubitx
Alf Baranda,
That is desirable.? The problems is the wire from the K3 relay.? That wire runs the full width of
the ubitx board and picks up rf. but if it were coax it would likely not.
Allison
|
Danial,
For the last 4 months this has been a significant discussion.? ubitx.net for one has it, the wiki has it
and the local wiki.
Spurs are when two or more signal mix and the products of that is the desired and many undesired signals.
Harmonics are simpler and are just the multiple of the signal as in *2 or *3 and can extend higher.
The answer is the low bands 80--20m have high harmonic output and the higher bands (17-10m) have spurs.
The spur issue is harder to get a good handle on.? There is a maybe solution but unconfirmed as yet.
The worst case spurs occurs when using 10M and results in a signal in an undesired signal around
16-17mhz (varies when where the tuning is in the 10M band).
The harmonic issues is simple, the existing harmonic filters are compromised by the board layout and
switching.? The fixes are use an external low pass filter for the desired band either switched or
manually inserted int he coax..? The other is surgery on the board to correct the circuit and rewire
so it works as intended.
Allison
|
Re: UBITX Q90 mod with BFR106
I'm thoroughly enjoying this discussion BUT how can I collect and save it all for later when I start on my attempt to flatten out or increase slightly the output power. Hopefully soon.
I found some better transistor sockets and a fantastic electric desoldering tool along with some genuine Motorola 2222a's for the project.
Is anyone collecting this info?
Bo W4GHV?
|
YO8UFO