Yesterday, I set up a separate antenna for the uBitX on my front porch, to test battery operations, potentially to use the rig in the field. The antenna I set up was not ideal, and my Elecraft T1 ATU would not tune it. But now I'm not so sure. I was powering the uBitX from a Stanley automotive jump and power box, the kind that has a lighter-type socket on the front, and automotive battery clamps on the back for jumping a car. The voltage is 13.7v, not a lot higher than what I was putting into it on the bench, which was 12.5v, but the available amperage was of course much higher -- this is a BIG jump box that I purchased for jump-starting my wheelchair van in an emergency.
I haven't measured the available amperage on the lighter socket, but I suspect it's much higher than the 1.5A I limited my bench power supply to giving. The bench supply has been set to 12.5v @ 1.5A, and with those settings I get almost exactly 5W out on both 40 and 20m into a big dummy load (the MFJ paint can model). But when I power it from the battery box, I get well over 5w, around 20 watts from whistling into the mike. The key gives a very high output power as well. It may be that it was too much output power for the tuner to handle, and it wouldn't such a strong signal.
My bench supply takes 19vdc in from a switching supply that gives 19v @ 3.5A, and allows the user to set a buck-boosted output between 0 and 18v, with commensurate amperage. The DC in socket I installed is the same size as the one on the uBitX, and most of my other projects, as I thought ahead to powering them. I just tested connecting the jump box to the bench supply, and the bench supply to the uBitX, and can keep the higher power from the battery from overpowering the radio. I'm going to order an extra bench supply module -- cheap on Ebay -- and install it permanently on the back of the uBitX to give me controllable flexibility in the output power. Running the uBitX at 12.5v @ 1A limit brings the output power into the dummy down to 2w.
Is there a point below which I might damage the radio from running it too low? Has anyone else had similar experience with too much amperage?
I'm going to rethink the speaker I have mounted in the case, as it doesn't have enough oomph to make it worthwhile. Or, I may add a small audio amp for the speaker. I have several in my junque box. Listening with a pair of headphones sounds great. I'm having no trouble with the audio on phones, just on speaker, and the incoming signals sound good. If nothing else, I have a 10w musical instrument amp from Monoprice on its way. I was going to use it for amplifying my harmonica, but I can use it for this without difficulty. It's a battery-powered model, so I'll be able to take it into the field as well.
I have some antenna kits on the way, including the multi-band antenna on the QRPGuys site and the parts for a "flimsy" W3EDP antenna on the way (I didn't have a 4:1 unun on hand; that's on order as well), and will report my results with them. I'm starting with a Sotabeams 40m end-fed with their "Pico Tuner", which I will be building today.
Gwen NG3P
|
Re: uBitxr4 audio distortion fix
Don鈥檛 forget those emitter resistors, that Add additional voltage drop.
Someone suggested using a bit of feedback, I didn鈥檛 look at the circuits, but wouldn鈥檛 that be one solution?
toggle quoted message
Show quoted text
Farhan,
It was too much! Q72 started to get hot but not Q73. Means they are not matched.
Iq went up almost 100mA. So I used a pot where 47 Ohms seems fine.
What may work that instead of these diodes use the same transistor BE junctions!
Then just two may work, need to experiment on this.
Raj
At 29-06-18, you wrote:
What if we use three diodes instead?脗
On Fri, 29 Jun 2018, 13:35 Raj vu2zap, < rajendrakumargg@...> wrote:
- Got back to town and plugged in the uBitxr4 and found the audio distorted.
- Poking around the finals I found that the two diodes D15 and D16 gave only a drop of 1.2V total
- but the final transistors needed more like 1.5V. i.e. 0.75v each.
- I simply cut the track between D5 and D16 and soldered a 100 ohms multiturn preset as shown
- in picture below. (Preset leads used is center and one side)
- Start with the two soldered connections of the preset set to ZERO ohms.
- Power on and tune to a station at low volume and slowly increase the preset till the audio
- becomes clear. In my board the RX power consumption increased by 25mA at the best sound.
- Just check and see that the output transistors are not getting hot.
- My board sounded great with 47 Ohms between D15 D16 and I run at 13.6V. If you run at the
- same supply voltage then you can try a fixed resistor. For 12V supply you could try a higher value
- like 56/62 or even 68 Ohms.
- Cheers
- --
- Raj, vu2zap
- Bengaluru, South India.
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Re: Known issues on uBITX r4
#ubitx
It seems there are still people who complain about the audio. Since most of the mods can be done post-construction, I'd put it together and judge for yourself. It's not an issue for me as the JackAl board has its own audio amp.
Jack, W8TEE
On Friday, June 29, 2018, 12:14:56 AM EDT, hirosmb JAZZ <hirosmb@...> wrote:
Jack,
Thanks for ur quick reply.
I read some articles of mods, but couldn鈥檛 recognize which are necessary mods for uBITX r4 board.
Does the r4 board still need to be fixed for the distortion issue?
// hiro
2018/06/29 12:38銆丣ack Purdum via Groups.Io < jjpurdum@...&驳迟;銇儭銉笺儷:
Most of the mods that have been made are summarized at:
Jack, W8TEE
On Thursday, June 28, 2018, 11:31:43 PM EDT, < hirosmb@...> wrote:
Hi, all.
I鈥檓 really new to uBITX and planning to place my order to very soon.
Then please share its known hardware issues of uBITX r4 that I need to modify or solder.
Thanks in advance and hope to QSO with my uBITX soon.
// hiro, JJ1FXF
|
Re: RFI from uBitx TX after AGC and other mods installed
Thanks Mark. I've usually try to use 14 AWG wire (or larger) for power feed and a nice big capacitor right after the power switch. In the BITXs I use an 8 volt pre-regulator to feed the Raduino. Probably why I have few problems. I'm hoping to hear from the others to see if their issues were related. Having that signal present on the power throughout the transceiver could create some real mysteries. 73, Don
|
Re: Latest Build, Mods and results.
Mike: Thanks for the link. Great job!
73,
Alan N4AYE
|
Re: uBitxr4 audio distortion fix
we will probably have to increase the emitter resistors in that case too. The other option would be to use slightly higher bias voltage rectifiers like the 1N4001s. - f
On Fri, Jun 29, 2018 at 4:17 PM, Raj vu2zap <rajendrakumargg@...> wrote:
Farhan,
It was too much! Q72 started to get hot but not Q73. Means they are not
matched.
Iq went up almost 100mA. So I used a pot where 47 Ohms seems
fine.
What may work that instead of these diodes use the same transistor BE
junctions!
Then just two may work, need to experiment on this.
Raj
At 29-06-18, you wrote:
What if we use three diodes
instead?脗
On Fri, 29 Jun 2018, 13:35 Raj vu2zap,
<
rajendrakumargg@...> wrote:
- Got back to town and plugged in the uBitxr4 and found the audio
distorted.
- Poking around the finals I found that the two diodes D15 and D16 gave
only a drop of 1.2V total
- but the final transistors needed more like 1.5V. i.e. 0.75v
each.
- I simply cut the track between D5 and D16 and soldered a 100 ohms
multiturn preset as shown
- in picture below. (Preset leads used is center and one side)
- Start with the two soldered connections of the preset set to ZERO
ohms.
- Power on and tune to a station at low volume and slowly increase the
preset till the audio
- becomes clear. In my board the RX power consumption increased by 25mA
at the best sound.
- Just check and see that the output transistors are not getting
hot.
- My board sounded great with 47 Ohms between D15 D16 and I run at
13.6V. If you run at the
- same supply voltage then you can try a fixed resistor. For 12V supply
you could try a higher value
- like 56/62 or even 68 Ohms.
- Cheers
- --
- Raj, vu2zap
- Bengaluru, South India.
![Emacs!]()
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|
Re: uBitxr4 audio distortion fix
Farhan,
It was too much! Q72 started to get hot but not Q73. Means they are not
matched.
Iq went up almost 100mA. So I used a pot where 47 Ohms seems
fine.
What may work that instead of these diodes use the same transistor BE
junctions!
Then just two may work, need to experiment on this.
Raj
At 29-06-18, you wrote:
toggle quoted message
Show quoted text
What if we use three diodes
instead?脗
On Fri, 29 Jun 2018, 13:35 Raj vu2zap,
<
rajendrakumargg@...> wrote:
- Got back to town and plugged in the uBitxr4 and found the audio
distorted.
- Poking around the finals I found that the two diodes D15 and D16 gave
only a drop of 1.2V total
- but the final transistors needed more like 1.5V. i.e. 0.75v
each.
- I simply cut the track between D5 and D16 and soldered a 100 ohms
multiturn preset as shown
- in picture below. (Preset leads used is center and one side)
- Start with the two soldered connections of the preset set to ZERO
ohms.
- Power on and tune to a station at low volume and slowly increase the
preset till the audio
- becomes clear. In my board the RX power consumption increased by 25mA
at the best sound.
- Just check and see that the output transistors are not getting
hot.
- My board sounded great with 47 Ohms between D15 D16 and I run at
13.6V. If you run at the
- same supply voltage then you can try a fixed resistor. For 12V supply
you could try a higher value
- like 56/62 or even 68 Ohms.
- Cheers
- --
- Raj, vu2zap
- Bengaluru, South India.
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|
Re: uBitxr4 audio distortion fix
What if we use three diodes instead?聽
Got back to town and plugged in the uBitxr4 and found the audio
distorted.
Poking around the finals I found that the two diodes D15 and D16 gave
only a drop of 1.2V total
but the final transistors needed more like 1.5V. i.e. 0.75v
each.
I simply cut the track between D5 and D16 and soldered a 100 ohms
multiturn preset as shown
in picture below. (Preset leads used is center and one side)
Start with the two soldered connections of the preset set to ZERO
ohms.
Power on and tune to a station at low volume and slowly increase the
preset till the audio
becomes clear. In my board the RX power consumption increased by 25mA at
the best sound.
Just check and see that the output transistors are not getting
hot.
My board sounded great with 47 Ohms between D15 D16 and I run at 13.6V.
If you run at the
same supply voltage then you can try a fixed resistor. For 12V supply you
could try a higher value
like 56/62 or even 68 Ohms.
Cheers
--
Raj, vu2zap
Bengaluru, South India.
|
Oms
Kindly share us the RX & TX reports of uBitx set ,Operated on original boards聽
i am expecting on the original boards results.
de
vu3pen
蝉谤颈诲丑补谤听
|
Re: A Breadboard Technique for the uBITX
Jack,
I鈥檓 taking this idea for which thank you.
What about the noise level which other radios or PCs places around the uBITX receive?
// hiro, JJ1FXF聽 2018/06/29 14:58銆丄ndy V. Borisenko via Groups.Io < rw9rn@...&驳迟;銇儭銉笺儷:
toggle quoted message
Show quoted text
nice job!
Jon,聽are there any problems with interference due to the display outside the board raduino?
|
Re: Known issues on uBITX r4
#ubitx
Yes, you are right, Raj.
I鈥檒l set up the uBITX as it comes at first.
My only concern was if I need to solder or mod at my first setting-up bcoz v4 is rather new design, I鈥檒l easily get confused what I do is ok or not.
Thanks for ur advice, Raj.
// hiro, JJ1FXF
2018/06/29 17:07銆丷aj vu2zap <rajendrakumargg@...&驳迟;銇儭銉笺儷:
toggle quoted message
Show quoted text
Hiro,
First connect up the board and get it working in stock condition and when all is
well and running look for mods that you may want to try.
I have posted the audio distortion fix just now. Its very simple to do.
Raj
At 29-06-18, you wrote:
Hi, all.
I鈥檓 really new to uBITX and planning to place my order to hfsignals.com very soon.
Then please share its known hardware issues of uBITX r4 that I need to modify or solder.
Thanks in advance and hope to QSO with my uBITX soon.
// hiro, JJ1FXF
|
Re: Known issues on uBITX r4
#ubitx
Hiro,
First connect up the board and get it working in stock condition and when all is
well and running look for mods that you may want to try.
I have posted the audio distortion fix just now. Its very simple to do.
Raj
toggle quoted message
Show quoted text
At 29-06-18, you wrote: Hi, all.
I抦 really new to uBITX and planning to place my order to hfsignals.com very soon.
Then please share its known hardware issues of uBITX r4 that I need to modify or solder.
Thanks in advance and hope to QSO with my uBITX soon.
// hiro, JJ1FXF
|
uBitxr4 audio distortion fix
Got back to town and plugged in the uBitxr4 and found the audio
distorted.
Poking around the finals I found that the two diodes D15 and D16 gave
only a drop of 1.2V total
but the final transistors needed more like 1.5V. i.e. 0.75v
each.
I simply cut the track between D5 and D16 and soldered a 100 ohms
multiturn preset as shown
in picture below. (Preset leads used is center and one side)
Start with the two soldered connections of the preset set to ZERO
ohms.
Power on and tune to a station at low volume and slowly increase the
preset till the audio
becomes clear. In my board the RX power consumption increased by 25mA at
the best sound.
Just check and see that the output transistors are not getting
hot.
My board sounded great with 47 Ohms between D15 D16 and I run at 13.6V.
If you run at the
same supply voltage then you can try a fixed resistor. For 12V supply you
could try a higher value
like 56/62 or even 68 Ohms.
Cheers
--
Raj, vu2zap
Bengaluru, South India.
|
Re: Known issues on uBITX r4
#ubitx
Many, many thanks for ur comments, Andy.
Now I understand that either a cheap speaker or bypassing built-in amp is the solution of the synchronized noise issue.
Since this fix isn鈥檛 hard one for me, now I鈥檓 placing my order sooner.
Again, thanks, Andy.
// hiro, JJ1FXF
2018/06/29 15:49銆丄ndy V. Borisenko via Groups.Io < rw9rn@...&驳迟;銇儭銉笺儷:
toggle quoted message
Show quoted text
in the message #52671聽solution a problem: "gentlemen, the question is closed.
I connected the cheapest computer speakers with a built-in amplifier and sent a signal to them bypassing the amplifier uBitx.
I got a good audio.
and "A re-setting of the BFO should fix this" did not have to do with it.
You just need not use the audio amplifier in uBitx. he is no good at all.
for me it's a fact!I previously wrote about problems with the audio amplifier v4.
I will build and instal in uBitx a wonderful audio filter and audio amplifier QCX from QRP-Labs.
best regards to all!
Andy V. Borisenko RW9RN"
#52684
"Farhan has an engineering error in the audio amplifier. I do not speak English well enough to explain this in detail. I will say simply: do not use the built-in amplifier in this form. It's easier and cheaper to signal bypass, to an external audio amplifier. this can be done by sending a signal from the yellow (signal) through the condenser 47-100 microfarad and green (ground), to an external audio amplifier."
|
Re: Known issues on uBITX r4
#ubitx
in the message #52671聽solution a problem: "gentlemen, the question is closed.
I connected the cheapest computer speakers with a built-in amplifier and sent a signal to them bypassing the amplifier uBitx.
I got a good audio.
and "A re-setting of the BFO should fix this" did not have to do with it.
You just need not use the audio amplifier in uBitx. he is no good at all.
for me it's a fact!I previously wrote about problems with the audio amplifier v4.
I will build and instal in uBitx a wonderful audio filter and audio amplifier QCX from QRP-Labs.
best regards to all!
Andy V. Borisenko RW9RN"
#52684
"Farhan has an engineering error in the audio amplifier. I do not speak English well enough to explain this in detail. I will say simply: do not use the built-in amplifier in this form. It's easier and cheaper to signal bypass, to an external audio amplifier. this can be done by sending a signal from the yellow (signal) through the condenser 47-100 microfarad and green (ground), to an external audio amplifier."
|
Re: Known issues on uBITX r4
#ubitx
I want to say that聽synchronized noise聽is a problem with an audio amplifier 聽v4.
tonight I will try to make a video where the built-in audio amplifier is turned off, and the sound goes through an external amplifier.
|
Re: Known issues on uBITX r4
#ubitx
Very much appreciated, Andy.
I鈥檇 like to compare its before/after.
What do u mean by 鈥渘o problem of audio鈥�?
Do u mean to say the synchronized noise is the spec of uBITX?
// hiro, JJ1FXF 2018/06/29 15:03銆丄ndy V. Borisenko via Groups.Io < rw9rn@...&驳迟;銇儭銉笺儷:
toggle quoted message
Show quoted text
Hiro
if necessary, I can shoot the video with an external (bypassing the built-in) audio amplifier.
but believe me, there is no problem with audio.
|
Re: Known issues on uBITX r4
#ubitx
Hiro
if necessary, I can shoot the video with an external (bypassing the built-in) audio amplifier.
but believe me, there is no problem with audio.
|
Re: Known issues on uBITX r4
#ubitx
Do all of the v4 have this distortion issue? Or 聽only for the certain lots?
Thanks, Andy.
Ur videos helped me to understand what the distortion issue is like.
// hiro, JJ1FXF
2018/06/29 14:47銆丄ndy V. Borisenko via Groups.Io < rw9rn@...&驳迟;銇儭銉笺儷:
toggle quoted message
Show quoted text
I have 聽v4.
big problems with sound.
if you bypass the built-in audio amplifier, then you can use it.
for example, a video from my uBitx v4
|
Re: Known issues on uBITX r4
#ubitx
I have 聽v4.
big problems with sound.
if you bypass the built-in audio amplifier, then you can use it.
for example, a video from my uBitx v4
|
Gwen Patton
Don, ND6T
Raj vu2zap
