None taken,
Send me a recording of that happening in your uBitx. What is the marking on the audio chip ?
In bitx40 there is a 100 Ohms and a diode in series with the LM386 which has packed up in one of my
boards. The diode was slowly charging the capacitor and audio would return and drop out.
Raj
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Show quoted text
At 29/05/2018, you wrote: Raj,
I meant no insult. I was confused. I see it turns out I was not being clear. I apologize. Can we please start over?
What was your idea, on the uBITX audio problem I described?
Thanks,
Dave
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Re: Simple sound card interface
#ft8
Wow, you went all out. I just used the volume controls on the sound card and the Kenwood. For the isolation transformers I am pretty sure they are Radio Shack audio transformers with one side being called 8 ohm and the other either 1000 or 500 ohm depending on the taps used.
I think it depends on where you tap into the audio out from the rig. I didn¡¯t feel like drilling another hole in my case, so I use the headphone out. To do that, I had to use a low to high impedance transformer. After that, I used a Jfet buffer and a volume pot. For the transmit side I only use a buffer and volume control. Already worked several stations on FT-8 and PSK-31.
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Re: Simple sound card interface
#ft8
I think it depends on where you tap into the audio out from the rig. I didn¡¯t feel like drilling another hole in my case, so I use the headphone out. To do that, I had to use a low to high impedance transformer. After that, I used a Jfet buffer and a volume pot. For the transmit side I only use a buffer and volume control. Already worked several stations on FT-8 and PSK-31.
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Re: Simple sound card interface
#ft8
Its been 8 years since I used PSK modulation and I remember that isolation transformers were a good idea but perhaps not absolutely necessary. I think I made a pair for both line-in and line-out. I still have them. At that time nothing else was required for I was using a Kenwood TS-440-SAT which had a jack in the back to use in lieu of the microphone. I also remember that PSK could be obtained by directly placing the computer's speaker against the microphone with the PTT held down so I am thinking that nothing is necessary for PSK beyond using isolation transformers and I don't think things have changed.?
For the other forms of digital modulation that have arrived in the past 8 years I am clueless.
On Mon, May 28, 2018, 11:13 PM Praba Karan < vu3dxr@...> wrote: I want try my ubitx for digital modes with external usb sound card and usb rs232 cable. Suggest simple interface setup for this. Are audio isolation transformers necessary in audio line?
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Simple sound card interface
#ft8
I want try my ubitx for digital modes with external usb sound card and usb rs232 cable. Suggest simple interface setup for this. Are audio isolation transformers necessary in audio line?
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Re: RF power chain mods and improvements..
I think I am confusing T10 and T11...
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Re: RF power chain mods and improvements..
Did a few more tests this morning on my 'proto' uBITX driver section. Have now hooked up the finals, RD16HHF1.?? The final stage is verbatim from the G6ALU 20W PA. Easily found with Google. To re-cap, First two stages are MPSH10's.? FET driver is a pair of 2N5109's.?? Finals RD16HHF1 pair. Mods:? 330pF across all emitter stages of the MPSH10's.? 2N5109 stage: 10R + 1nF across the 22R emitters.? All transformers as per uBITX and G6ALU. Result with -30dBm input and ~12.1V dc on the setup, measured at PA.? With ~13vdc at PA, output on 80M for example is around 20W and 18.3W on 10M. Clearly more volts is better. Power was measured with a 200MHz scope at the PA output pins.
| ? |
-30dBm in |
| 1.8MHz |
14.2w |
| 3.5 |
15.23 |
| 7 |
16.00 |
| 14 |
13.94 |
| 28 |
13.00 |
I measured harmonic output also at above levels.? All look pretty good.? If the input level is increased by 2dB then it's obvious the PA is starting to compress and harmonic levels rise rapidly. So I think around the -30dBm input level and the power above is about optimum. The following pictures are harmonic plots, 80, 40, 20 & 10M bands.. NOTE the GREEN line should be 10dB lower, representing 0dB gain.
Would like to see somebody verify my results. AND: Has anybody measured the response of the uBITX Low pass Filters? glenn vk3pe
    
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Re: Receive FM Radio Station
#bitx40
Well, it shows that if you research the Baofeng microphone/speaker it can be made to work with the rig. It also pays to be careful for the little speaker/microphones that you can buy for handheld 2 meter radios often have to have what radio they are being purchased for specified because of impedance issues. I have one where I specified the radio it was for and MFJ sent the wrong one so yes, it works but you have to turn the volume full up to hear it and yell into the microphone to be heard.
Personally, I run the audio from the speaker/headphone jack of the radio into the line-in RCA inputs meant for audio visual input found on the back of my stereo. The volume is plenty adequate and the bass output is superior to a small speaker.
On the microphone I am hearing that the gain of the amp it feeds which is a 2n3904 transistor based amp with a voltage divider biasing network is too weak. Some of the guys soldered in a resistor parallel to Re in the biasing network to increase the gain with great results. I don't have steady enough hands to make that fix so I am going to see if I can increase the signal into the base of the 2n3904 with an outboard pre-amp for the Mic. I think that I will simulate the circuitry before I assemble anything and I am in no hurry because my listening time far out weighs my PTT time.
Needless to say I am glad you have audio now and again I don't know what to tell you above what I have to solve your FM interference issue.
On Mon, May 28, 2018, 7:02 PM Jerry Gaffke via Groups.Io <jgaffke= [email protected]> wrote: I just searched this forum for Baofeng, got dozens of hits from people using it with *Bitx* rigs.
Here's one of many threads:? /g/BITX20/topic/4554574
The microphone element is electret, just like the element suppied with the *Bitx*.
If the Baofeng element doesn't sound quite right, could patch in the one supplied with the rig.
Such a tiny speaker is bound to be a compromise, I wouldn't expect much from that.
The PTT switch arrangement looks pretty good, that alone is well worth $3.
Some of the Baofeng mikes on ebay are apparently even cheaper cones, there are some differences.
There is a bunch of stuff in that mike you don't need.
I'd replace the cable, using one with 3 wires for ground, ptt, and mike into a 3.5mm phone jack.
The ground goes to the ground side of the mike, also to one side of the ptt switch.
And of course the mike wire goes to the other side of the mike, the ptt wire goes to the other side of the ptt switch.
On Mon, May 28, 2018 at 01:33 pm, Mike aka KC2WVB wrote:
I just googled the Baofeng speaker. I see it is a combination microphone/speaker that is probably used on VHF portables.
?
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Re: A steal for Arduino Experimenters
May I suggest you buy "Beginning C for Arduino, Second Edition" by Jack Purdum. He is a member of this group.? I learned a lot from it.? I found mine on Amazon. -- Lee - N9LO? "I Void Warranties"
?
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Yes certainly the impedance is going to change as voltage is getting increased. A rule of thumb to calculate the impedance at the transiter's drain / collector is
Vcc squre / 2Pout so as Vcc i.e. supply voltage is almost getting doubled the
impedance is going to change
On Tue, May 29, 2018 at 5:35 AM, <vu3dkk@...> wrote: Hi all,recently I saw an IRFP250 based push pull amplifier circuit.In that design they use 13.8V power supply, but I have a 27V(40A) supply in my bench.My questions are
1)Will the impedance of the amplifier change when changing the power supply?
2)If it changes.then how to calculate the load impedance of the amplifier,and thus how to design a new output coupling transformer?
(I am going to use this for 40m)
Thanks in advance ............73
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Re: A steal for Arduino Experimenters
I ordered and received the Basic Starter Kit from Bangood.? The kit, however, has no 'help' manual but a later post included a web address from Bangood to send for the free PDF starter guide.? That link did not work.? I wrote Bangood and, after two requests, received a 75mb zipped file.? I tried to unzip it and was given the message that the file couldn't be unzipped as it was corrupted.
Several requests to Bangood to send re-send the file have fallen on deaf ears.
So......has anyone received the PDF that could forward me a copy?? It would be greatly appreciated as this nubee needs all the help he can get in experimenting with the Arduino.?
Thanks,
Keith AG?H
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I doubt it's related.
toggle quoted message
Show quoted text
On Mon, May 28, 2018 at 05:54 pm, Bo Barry wrote:
Its gone now. Evidently linked to the free books confusion which has been deleted.
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Re: Need help understanding a line of code in ubitx_si5351.cpp (msxp2 = ...)
#radiuno
The SI5340 datasheet says a step size of 0.001 ppb? (parts per billion).
So if creating a signal at 440mhz, you can adjust it in steps of 440e6 * 0.001/1e9 = 0.00044 hz.
Better have a stable reference osc into the Si5340 to see that kind of performance.
An Si5351 on some serious steroids.
?
Jerry, KE7ER
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Show quoted text
On Mon, May 28, 2018 at 05:46 pm, Jerry Gaffke wrote:
resolution of ppb,
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Its gone now. Evidently linked to the free books confusion which has been deleted.
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Or my phone. When I reply to the group I get a popup for some winning or freebie that only has a OK exit.
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Re: Need help understanding a line of code in ubitx_si5351.cpp (msxp2 = ...)
#radiuno
I have no idea at what point phase noise will be an issue for the si5351 across?
the various modes of operation, be it SSB, CW, FM,? or digital.
I do know that it works to 200mhz, you can push it to almost 300mhz.
Phase noise and resolution of the si5351 will be 10x worse at 200mhz than at 20mhz.?
Bringing on an Si5340 would be a nice handy sledge hammer for prototyping,?
goes up to 1028mhz, resolution of ppb, and has very low jitter.??
Likely cheaper and lower power ways to do what you need, but it's a nice part.
Not many hobbyists are using it, you might be writing your own code, and that could get nasty,
The Si5338 is a bit cheaper, and lower performance.?
But better than the Si5351.
Again, you might be writing your own code.
Both cost a fair bit more than the $1 Si5351, and are surface mount with a bunch of pins.
Jerry
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Show quoted text
On Mon, May 28, 2018 at 03:21 pm, Terry Morris wrote:
Both the question and the response/answer are intriguing to me. Mostly the answer. I don't comprehend most of the answer but I think I get the gist of it. Regarding the latter part of Jerry's conversation speaking about the Si5338, Si5340, and Si5341 is there any other downside other than the loss of about 1 w at 1.8v? I am presuming from your explanation of these devices that there is a positive advantage to using them, not only for 2 meter capability, but for better phase noise suppression and better crosstalk reduction. In an example that I might understand better, would using any of those 3 devices be like the performance difference between an analogue HW-9 and any of the modern commercial transceivers?
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Re: RF power chain mods and improvements..
¡°? There seem to be many combinations listed for that balun core for the turns and capacitor.I have seen capacitors listed from 33 pf to 330 pf. ¡°
Some with IRF510¡¯s, others with RD16¡¯s, and with different driver transistors and mods to the surounding caps and resistors. It¡¯s quite a tangle. I suspect the ideal cores and turns and, if needed, cap across the primary might be different for the different finals and might change depending on what they are being matched to on the driver side. So many possiblities. I check frequently to see what prgress has been made and thank the empiricists for trying what they had on hand and sharing the results. And hope Allison will get better soon.
jerry aa1of
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Re: RF power chain mods and improvements..
?Wow.....Kee's kits are an incredible list of projects.? ?I'm blown away by his productivity.? ? Perhaps when I retire I'll be able to do more kit building!!!
gordon
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Show quoted text
Calculating the impedance, the transformer has to be closer to
1:2 for this device at 13.6V.? I use a ?BN61-002 and it seems to be the winner for me so far (more efficient than the 43 type material), but others have found that a 1:2 BD43-302 works ok too.? Doesn¡¯t heat up at full power and is extremely wide banded¡? You
should look at the references on Kees website (K5BCQ Kits) regarding his 20W RD16HHF1 transistorized amplifier.?? They will give you good information.
?
?
?
?
?
?
Dr. William J. Schmidt - K9HZ
?
From: [email protected] [mailto:[email protected]]
On Behalf Of Ralph Mowery
Sent: Monday, May 28, 2018 10:56 AM
To: [email protected]
Subject: Re: [BITX20] RF power chain mods and improvements..
?
I have replaced the finals with the RD16hhf1 from RF Parts, capacitors across R 87,88,? feedback on finals to 1 K and the binocular output transformer.? I have seen several values of capacitors across the transformer
and tried a couple.? Right now I am using 150 pf .? I am using the 2 turns/ 3 turns on the output.
I take it from what you are saying, I should go from maybe 1 turn and 2 turns on the transformer ?? What value of capacitor do you recommend if I do that ?
Here is what I am getting now with the drive pot cut back some and either 250 or 300 ma for the bias, forgot which.
band? power? ?Amp ( 175 ma in the receive mode)
80? ? ? ?16 watts? ?3.4 amps
40? ? ? ?13.5? ? ? ? ?2.7
20? ? ? ? 8.5? ? ? ? ? 2.1
15? ? ? ? 7.0? ? ? ? ? 1.5
10? ? ? ? 8.7? ? ? ? ? 1.9
This was with an IFR 1200s and Fluke multimeter with 13 volts measured at the power connector on the circuit board .? The power supply is an Astron 50 amp.
Seems the efficiency is only about 35 % in rough numbers.
I do have a very large heat sink as the ubitx just fit in an old BUD box and I had originally cut a hole in the back so the original heat sinks would fit.
I do have a good electronic understanding in general, but not much experience with RF design.? I am more of a technician than engineer.? I bought this ubitx to play with and learn.? Thanks to Mr Farhan for the
design and kit.
Other than playing and learning with it, I plan on using it with some of the vhf/uhf converters off ebay from the Ukraine.? I have? a 2 meter one and it seems to receive very well.? Have not tested the transmit
yet as I am still modifying the ubitx.
?
?
On Mon, May 28, 2018 at 10:49 AM, ajparent1/KB1GMX <kb1gmx@...> wrote:
>>R86 20uH added in series<<
Why 20uh?? something more like 3.3 or 4.7uh is more reasonable and avoids a self resonance
around 16mhz or so depending on the inductor used.
Also what is the input current at 80M and 10W (at 12.6v) it should be near 2A (1.9 to maybe 2.1)?
I found with a 2:3 transformer its was nearly 3A (poor efficiency) and with 2:4 it was also?
high 2.5A.? Poor efficiency show as heating in the finals.? High currents and low output indicate
the transformer is not doing the job likely due to load mismatch.
I'm not a fan of the plastic 2n2222 parts.? Every time I've used them instead of the metal
I got inferior results.? ?They just do not behave the same at higher currents at higher
frequencies.?
Soon as the stiffness in my hands subsides I'm back on the bench to do some testing.
Allison
?
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Re: RF power chain mods and improvements..
I didn¡¯t say there would be a lot of power, but it does work¡ and the most obvious answer is a fifth filter.
?
?
Dr. William J. Schmidt - K9HZ
?
From: [email protected] [mailto:[email protected]] On Behalf Of ajparent1/KB1GMX
Sent: Monday, May 28, 2018 12:35 PM
To: [email protected]
Subject: Re: [BITX20] RF power chain mods and improvements..
?
Ralph,
Ok 13.8V at 3A (allow about 450 for the relays and all) is 41W in and 16 out and that means
the rest is heat in the finals.? That efficiency is way low blow 35%.? For a push pull at HF
45% is the bottom (start looking for reasons) as id expect about 55%.? ?Granted it can vary
with frequency but usually it decreases with higher frequency.
The output transformer may be either not enough inductance, turns or wrong ratio.
you say your using IFR1200?? IFS that a service monitor.
William,
If I see power at 6M there is a problem!? ?Translation is that at 6M i'd expect the output
to be at least 30db down from 10M or the low pass filter is very broken.? Also the low pass
filter L1-L4 with associated caps is not working as the cutoff is around 35mhz.
The problem is with only 4 filters what cutoff frequencies can you use that allow sufficient
second and third harmonic suppression that includes 6M?? And Meet the VHF requirements..
Doing 6M with only 4 filters pretty much means giving up bands and likely then other issues?
come to the forefront.
Allison
?
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Re: RF power chain mods and improvements..
Calculating the impedance, the transformer has to be closer to 1:2 for this device at 13.6V.? I use a ?BN61-002 and it seems to be the winner for me so far (more efficient than the 43 type material), but others have found that a 1:2 BD43-302 works ok too.? Doesn¡¯t heat up at full power and is extremely wide banded¡? You should look at the references on Kees website (K5BCQ Kits) regarding his 20W RD16HHF1 transistorized amplifier.?? They will give you good information.
?
?
?
?
?
?
Dr. William J. Schmidt - K9HZ
?
From: [email protected] [mailto:[email protected]] On Behalf Of Ralph Mowery
Sent: Monday, May 28, 2018 10:56 AM
To: [email protected]
Subject: Re: [BITX20] RF power chain mods and improvements..
?
I have replaced the finals with the RD16hhf1 from RF Parts, capacitors across R 87,88,? feedback on finals to 1 K and the binocular output transformer.? I have seen several values of capacitors across the transformer and tried a couple.? Right now I am using 150 pf .? I am using the 2 turns/ 3 turns on the output.
I take it from what you are saying, I should go from maybe 1 turn and 2 turns on the transformer ?? What value of capacitor do you recommend if I do that ?
Here is what I am getting now with the drive pot cut back some and either 250 or 300 ma for the bias, forgot which.
band? power? ?Amp ( 175 ma in the receive mode)
80? ? ? ?16 watts? ?3.4 amps
40? ? ? ?13.5? ? ? ? ?2.7
20? ? ? ? 8.5? ? ? ? ? 2.1
15? ? ? ? 7.0? ? ? ? ? 1.5
10? ? ? ? 8.7? ? ? ? ? 1.9
This was with an IFR 1200s and Fluke multimeter with 13 volts measured at the power connector on the circuit board .? The power supply is an Astron 50 amp.
Seems the efficiency is only about 35 % in rough numbers.
I do have a very large heat sink as the ubitx just fit in an old BUD box and I had originally cut a hole in the back so the original heat sinks would fit.
I do have a good electronic understanding in general, but not much experience with RF design.? I am more of a technician than engineer.? I bought this ubitx to play with and learn.? Thanks to Mr Farhan for the design and kit.
Other than playing and learning with it, I plan on using it with some of the vhf/uhf converters off ebay from the Ukraine.? I have? a 2 meter one and it seems to receive very well.? Have not tested the transmit yet as I am still modifying the ubitx.
?
?
On Mon, May 28, 2018 at 10:49 AM, ajparent1/KB1GMX <kb1gmx@...> wrote:
>>R86 20uH added in series<<
Why 20uh?? something more like 3.3 or 4.7uh is more reasonable and avoids a self resonance
around 16mhz or so depending on the inductor used.
Also what is the input current at 80M and 10W (at 12.6v) it should be near 2A (1.9 to maybe 2.1)?
I found with a 2:3 transformer its was nearly 3A (poor efficiency) and with 2:4 it was also?
high 2.5A.? Poor efficiency show as heating in the finals.? High currents and low output indicate
the transformer is not doing the job likely due to load mismatch.
I'm not a fan of the plastic 2n2222 parts.? Every time I've used them instead of the metal
I got inferior results.? ?They just do not behave the same at higher currents at higher
frequencies.?
Soon as the stiffness in my hands subsides I'm back on the bench to do some testing.
Allison
?
|
Raj vu2zap
Lee
Satish Chandorkar
K9HZ
