Re: click fix and squeal on transmit
#ubitx
Thanks, Don! In a surprise move, the problem turned out to be uncarefulness on my part. My confidence was misplaced, since I'd used wrong capacitors in a total of four places: both caps in the circuit were 10¦Ìf, not 10 nf, and my replacements for C50 and C63 were not polarized. Now that I've replaced all four with the correct caps, the squeal is gone. The click is still audible in the headphones when the volume pot is turned way up, but it's much less than before. I think I'm going to declare this a qualified success and put the radio back in its enclosure.
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Re: Off Topic: Gap Antennas
If you can, put in 8.8.8.8 for your first name server and see if that does it. That's google's name server.
Vince - K8ZW.
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On 08/02/2018 04:02 AM, DaveC wrote: Thanks guys, Don't think it has anything to do with the EU privacy
issues also cleared out all cookies etc and no change.
It looks like a DNS issue and somewhere in the chain from the masters an
update error is occurring.
73 Dave G8PGO
--
Michigan VHF Corp.
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I went a slightly different direction and picked up a cheap temp fan relay from Amazon:
I superglued the probe to one of the finals heatsink and then played with ON temp and hysteresis temp, I settled on 50deg ON and 35deg OFF.? It was $5 for the fan relay + probe and ~$8 for a 12v 2wire fan.? Works great.
73 Rob de AG5OV
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Re: click fix and squeal on transmit
#ubitx
When the rig is not powered or in the receive mode there should be continuity from the Rx connection point to 12V. through relay K1 contacts 3 and 5. That is normal. The squeal is not!
First step in diagnosis is to check the voltage on the gate of Q3 when in transmit mode. It should be below 1 volt referenced to the ground connection on that board. If not, check to see that the ground connection there has the same potential as the ground plane of the BITX. Then track down the voltage discrepancy. The operation depends on Q3, acting as a gate, being turned off, thus opening that gate. If that gate is allowing the I/O (when in transmit, it is the microphone pre-amp output) to be leaking into the audio output then you will get enough feedback to oscillate. If the gate of Q3 is below 1 volt referenced to the source during transmit then Q3 may be bad. If there is voltage on the source, check your solder connections of R4.
Keep us informed, please. 73, -Don
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Re: Ubitx will be here tomorrow. Any suggestions for a Bitx newbie
#ubitx
Hi there..
do step 3 before step 2. Install that resistor first. Then apply power.
4. The software is already 'loaded'.
After you install in a case you will have left me behind. I am not interested in touch screens, etc. Enjoy your new radio:)
73,
Bill KU8H
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On 08/02/2018 01:38 PM, Truffies wrote: I just received my ubitx building this weekend on cardboard to see if works.
Questions on steps
1. build on cardboard
2. power
3 place 4.7k in key jack
4 ? do you need to load software?
5. Final listern test to see bands turning rec.
6. Test in dumb load transmit
7. OK build into a case
8. now ready to modify - AGC
9. LCD touch screen add software first to use screen?
(load hex and how to do in steps please where to find) dumb all new to me
-----Original Message-----
From: ajparent1/KB1GMX
Sent: Aug 2, 2018 1:22 PM
To: [email protected]
Subject: Re: [BITX20] Ubitx will be here tomorrow. Any suggestions
for a Bitx newbie #ubitx
ITs been said but I will repeat.
Build it first and test. Insure you have the 4.7K in place on the
key jack. Double check wiring.
If you are bench testing before boxing it. Use care to avoid
accidental shorts or wires touching
the wrong thing and outside events like ESD (carpet static!). One
example seen was taped to
a piece of card board to keep everything from moving around, worked
well too.
Use 13.8 volts for testing as its likely a V4 board (discrete
transistor audio amp).
If all goes well you may want mods and to pick out what your box is
to look like.
Good luck!
Allison
--
bark less - wag more
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Re: Harmonic performance - SSB vs CW
Allison
I will try lowering the drive to see if it corrects the problem but I am skeptical. I first noted the problem when probing TP1 with the PA unpowered. The discrepancy is already visible at that point. It is pretty clear the harmonics are being generated at the unbalanced mixer.
WA8TOD
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Re: Ubitx will be here tomorrow. Any suggestions for a Bitx newbie
#ubitx
I just received my ubitx building this weekend on cardboard to see if works.
Questions on steps
1. build on cardboard 2. power 3 place 4.7k in key jack 4? ? do you need? to load software? 5. Final listern test to see bands turning rec. 6. Test in dumb load transmit 7. OK build into a case 8. now ready to modify - AGC 9. LCD touch screen add software first to use screen? ? (load hex and how to do in steps please where to find)? dumb all new to me
-----Original Message-----
From: ajparent1/KB1GMX
Sent: Aug 2, 2018 1:22 PM
To: [email protected]
Subject: Re: [BITX20] Ubitx will be here tomorrow. Any suggestions for a Bitx newbie #ubitx
ITs been said but I will repeat.
Build it first and test.? Insure you have the 4.7K in place on the key jack.? Double check wiring.
If you are bench testing before boxing it.? Use care to avoid accidental shorts or wires touching
the wrong thing and outside events like ESD (carpet static!).? One example seen was taped to
a piece of card board to keep everything from moving around, worked well too.
Use 13.8 volts for testing as its likely a V4 board (discrete transistor audio amp).
If all goes well you may want mods and to pick out what your box is to look like.
Good luck!
Allison
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Re: Ubitx will be here tomorrow. Any suggestions for a Bitx newbie
#ubitx
ITs been said but I will repeat.
Build it first and test.? Insure you have the 4.7K in place on the key jack.? Double check wiring.
If you are bench testing before boxing it.? Use care to avoid accidental shorts or wires touching
the wrong thing and outside events like ESD (carpet static!).? One example seen was taped to
a piece of card board to keep everything from moving around, worked well too.
Use 13.8 volts for testing as its likely a V4 board (discrete transistor audio amp).
If all goes well you may want mods and to pick out what your box is to look like.
Good luck!
Allison
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Re: Harmonic performance - SSB vs CW
Warren,
During my sessions testing the amp it was noticed but the 20Mhz and up spur was higher?
on the priority list.
Another thing I ran into with a friend was defective low pass filters.? The toroids had different?
numbers of turns from other units.??
First try lowering the drive (RV1) and look again.? If it drops its the amp flat topping (overdrive)
(can be any stage in the amp up to including the finals.).? That can be voltage starving (less than?
12V at the board) or other problem unnoticed.
It is possible that the first amp Q90 is being over driven as well and reducing RV1 will not help then.
Generally the CW drive was found to be higher than clean levels of SSB drive so it could?
be amp overdrive.? Lowering the DC bias to the mixer during CW TX can help that.? The
Mixer (DBM) is?being used as a switch but they can also be used as a variable attenuator
as well.? R114 is the?point of adjustment.? Non linear action by the diodes is not an issue
as the driving waveform?is square to start with which is why the odd harmonics are stronger
on the display.? Add to?that the push pull amps (driver and final) are balanced so the second
and forth are better?suppressed but 3 and fifth tend to be the push pull amps weak spot.
Also sweep the 3-5mhz filter to insure its working as expected.? Easy to do with power off
and tracking generator?as its then isolated.? Also make sure the correct filter is being
selected, TX-A/B/C should?all be selected (relay active).
If the TX amp is at or near compression try turning up the DC power a Volt or so (caution TA2822!).
If the TA2822 is on separate regulated power its safe to go far higher than 13V.
Test first as there are many possible solutions depending on the problem.
Allison
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Re: Harmonic performance - SSB vs CW
That's an interesting finding, and seems quite likely correct.
Thanks for looking into that.
One possible solution would be to unbalance either the modulator (as done on the Bitx40 by Allard's mods)?
or the second mixer at D3,D4.? In either case, those harmonics should be stripped out by the 45mhz filter
(also the 12mhz filter, in the case of unbalancing the modulator).? Would require minor hacks to the
firmware to set up the si5351 correctly for CW transmissions after this mod.
Jerry, KE7ER
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On Thu, Aug 2, 2018 at 09:26 AM, Warren Allgyer wrote:
I am noting a significant difference in the harmonic suppression in SSB mode versus CW mode.?
The two signals are generated in a very different way. SSB is generated at 45 MHz and mixed down to the final transmit frequency by combining with the first oscillator in the balanced first mixer to make the SSB transmission. In CW the 45 MHz path is disabled and the first oscillator is simply moved to the transmit frequency. The first mixer is unbalanced with a DC bias to allow the first oscillator signal to leak through.
It appears the act of unbalancing this mixer produces harmonics, particularly high order odd harmonics that are clearly in excess of the -43 dBc requirement.
The screenshot shows? the harmonics of an 80 meter transmission at 10 watts. The purple trace is the CW and the blue trace is SSB. Signal source for SSB is a approximately -40 dBV 1 KHz tone with the level adjusted to match the CW carrier level. The SSB signal harmonic suppression is just adequate (green display line) however the CW signal is clearly non-compliant.
I am not sure what to do about it yet but wanted to raise the point. I have done a search on this board since I am new and I do not find this has been reported before..... perhaps I missed it?
WA8TOD
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Harmonic performance - SSB vs CW
I am noting a significant difference in the harmonic suppression in SSB mode versus CW mode.?
The two signals are generated in a very different way. SSB is generated at 45 MHz and mixed down to the final transmit frequency by combining with the first oscillator in the balanced first mixer to make the SSB transmission. In CW the 45 MHz path is disabled and the first oscillator is simply moved to the transmit frequency. The first mixer is unbalanced with a DC bias to allow the first oscillator signal to leak through.
It appears the act of unbalancing this mixer produces harmonics, particularly high order odd harmonics that are clearly in excess of the -43 dBc requirement.
The screenshot shows? the harmonics of an 80 meter transmission at 10 watts. The purple trace is the CW and the blue trace is SSB. Signal source for SSB is a approximately -40 dBV 1 KHz tone with the level adjusted to match the CW carrier level. The SSB signal harmonic suppression is just adequate (green display line) however the CW signal is clearly non-compliant.
I am not sure what to do about it yet but wanted to raise the point. I have done a search on this board since I am new and I do not find this has been reported before..... perhaps I missed it?
WA8TOD
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click fix and squeal on transmit
#ubitx
Hi -- I have had my v3 ubitx working fine, and thought I would install the T/R click fix version 2 from . I'm fairly confident in the circuit I assembled, slightly less confident in the jumpers, trace-cutting, and attachment to the board. The click is still audible in the relay but not in headphones on either transition, and I get a loud squeal on transmit into a dummy load when the volume pot is more than slightly turned up. What should I be looking at to diagnose this? I noticed continuity between the 12v line and the point marked Rx connection in this section after cutting the trace, which seemed odd: 
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Re: RFI Problem related by routing audio through K3 (uBitx)?
Printed Wiring Board,? a.k.a. circuit board.
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Re: ND6T AGC and Click kit wiring notes
Looks very nice Nick, good luck with it.
You might also label the "+" via on the 5V input since we had some confusion there, and the other grounds (audio, etc).
73 Kees K5BCQ
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Re: Ubitx will be here tomorrow. Any suggestions for a Bitx newbie
#ubitx
Use the Groups wiki site...? /g/BITX20/wiki/home??and make corrections and additions if you feel its needed.? And what they said, build it vanilla first. Enjoy, its a fun rig, W7PEA | Patrick
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Mike :
It certainly sounds like RF getting into where it doesn't belong. ?End-fed wires are notorious for bringing RF into the shack.
I would suggest trying to put a ferrite choke on the power leads and keeping them as short as possible.
?
Any external wires (PTT, Mic, key, power, headphones) might be acting like an antenna and allowing
RF in where it isn't wanted.?
Is there any way that you can try a different coax fed antenna ? Maybe try the same configuration at a friends place where they?
have different antenna setup ? ?That would at least allow you to rule out some internal issue in the radio. ?If you can't reproduce the
issue elsewhere with a real antenna on it then it is likely something specific to your use of the end-fed wire and resulting RFI.?
Cheers
Michael VE3WMB?
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Re: uBITX HF transceiver and blue MBITX metal case.
Eddie, ? ? ? ? ? ? Check this out(from Google)
https://appletoolbox.com/2015/10/how-to-extract-rar-files-on-mac-osx/
7
Sunil Sankaranarayanan VU2MTM
?
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Re: ubitx and case for sale
FET 2N4091 metal case JFET or equivalent. Must be metal case for freq stab.? Bipolars : MPSH 10 or better use? the? BSX-20 which has a FT of 500 Mhz and very low input capacitance c/w 2n2222.? and get rid of the silly 9v regulator chain use an LM 78L09 regulator chip or similar. TEF
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My QTH is the east coast of Ireland, so will be very lucky to receive the 5, 10Mhz WWV?transmissions, for Zero Beat calibration, given the propagation conditions lately.
I'll have to tune to a local AM broadcast channel.
Thanks for the suggestion anyway.
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Re: ubitx and case for sale
I am not interested in purchase but if you do sell and want to stay in the hobby , without much more money you could buy a CS? SSB transceiver from?
He has an agent in Nth America.? Unless he forces you to go direct to the US agent? then you can purchase at USD 120, 10 shipping and about $25 assly charge as I am guessing you would not be willing to assemble and test because of risk of it not working and then your getting stuck.? ?THIS is a MONO band transmitter and it is blind. you know you are in band because it it DDS controlled , ie a local oscillator from a quartz time based? but unless you build yourself a marker generator you don't know where exactly you are (you can however put a calibration cheat around the dial). These use a generic IRF 530 Mosfet as the final? so if the final blows you can replace it for around $1.50 or so. It is theoretically possible to convert this transceiver so it can do CW as well though it would give the internal relays a? bit of a hammering. You may never want CW.? ?The other option is another monobander from OzQRP? which is Run by Leon in Canberra area.? He sells a sort of Bitx .. all anlogue and you can either make your own VFO or use his CVS I think he calls it.. which sells for USD 45 equivalent and is a very slick looking unit with a multiline illuminated pixel display doodad.? If you want to roll your own VFO you can use one of? A Farhan's designs .. I will attach a rather sleek one .. you can get the FET from either Rockby electronics in Melbourne? or from Dan's kits and parts in Mo in US.? There are several sources for air variables NOS on the web INcluding ONe I saw in the US for less than $10. Contact me directly for details. What you could do is set yourself the target of getting a VFO going and if that fails go for a? built up transceiver and if you pass then you can buy either? of the above transceivers as a kit...with the OzQRP unit you already have an agricultural VFO going and you need only buy the base transmitter kit sans vfo.? Eventually you will get fed up with the analogue vfo and will buy the CVS and integrate that in? your box. The Farhan design shown needs to be rejigged to tune 2.8 to 3 Mhz so it produces 7 to 7.2 Mhz when subtracted from the IF frequency of 10 Mhz that Ozqrp use. If you treated your tecnician licence study seriously you can do those calcs. It really needs the coil rebuilt as a T50-6 toroid. You can most likely get one of those as a one off from Fred at Far circuits, or you can get it and a few other toroids and semis as a bunch from? the Toroid King in Florida.? The Farhan schematic has a few idiocies. Firstly there is a resistor with a missing value. Anything from 50 to 100 R will work . THere is an electrolytic wit no value , use 10uF and the tapping point on the coil is not show, use 1/3 turns up from the grounded end.? If you are to do any experimentation at all you will need a frequency counter and I have just heard of one that? as? bare unit sounds plausible. 6 digits? eg 14 020 1 Mhz ie down to the 100s of hertz resolution $ 13 USD. Obviously ex PRC.? It will be an extension of the Wolf Buscher design. ..almost for sure.? have a look at ? ? ?site and good luck with what you try to do. Subs. BFW11 Unavailable . Use 2N xxxx I am dead tired and might muck up and lose this post so contract me direct for trans and FET subs if you are going lto built the VFO.
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Don, ND6T
Frank_EI8HIB
