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Re: Help with troubleshooting Bitx40 - no transmit.
#bitx40help
It's good you posted this information with such a clear photo.
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But I have a thing about giving credit where credit is due, especially if that source can give needed additional details. The back-to-back diode mod comes from Raj: ??/g/BITX20/message/19105 Note that he suggested adding an incandescent lamp, which can be quite effective: /g/BITX20/message/21901 Here's a few more notes about what can blow in that transmitter: /g/BITX20/message/31352 As mentioned previously, I believe Don Cantrell is the source of the 100pf mod to the LPF. His blog post gives considerable detail, including before and after plots: ??? Jerry, KE7ER On Wed, Oct 25, 2017 at 06:31 am, Al Duncan VE3RRD wrote:
Don't forget to add the two 1N4148 protection diodes as shown at . Worthwhile added insurance for your BITX40. |
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Re: I made a mistake
You can put them back if you wish after testing, but "they aren't serving any purpose and can be removed from the board"
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means you don't have to. K1 is one of the two big black boxy things on your board, a relay (which could be called a solenoid switch). The relays are labeled K1 and K2 in the schematic at ? ? Perhaps a bit confusing as each one has two double pole switches plus a coil in the schematic, and while close together they don't have a box around them. ?Each relay has pins into the board labeled in the schematic as??1,3,5,8,9,12,14,16 If you put amps through a part of your DVM that was expecting milliamps, that part of it is probably blown. At least the shunt resistor used for milliamps is blown. ?Could be the damage went further. Test your meter somehow. ?For example, a 12v battery through a 1k resistor will give 12v/1000ohms = 0.012 amps = 12 milliamps and the resistor will have to dissipate 12v*0.012a = 0.144 watts, so a quarter watt resistor should do fine. And 12v/10ohms = 1.2 amps, but that 10 ohm resistor will be dissipating 12*1.2=14.4 watts, so you would want at least a 5 watt resistor for a quick one second test. ?That resistor will get very hot very quickly. On Wed, Oct 25, 2017 at 03:26 am, Barrett O wrote:
Since D7 and C130 ?aren't wired up right, they aren't serving any purpose and can be removed from the boardYou mean remove just temporary for testing?? |
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Re: Help with troubleshooting Bitx40 - no transmit.
#bitx40help
Don't forget to add the two 1N4148 protection diodes as shown at . Worthwhile added insurance for your BITX40.
73, AL? VE3RRD |
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Re: uBITX Questions
the comment is here under quote
"When I first built the LO system I did not pay attention to setting the VFO output level and for reasons I can't remember, the VFO output was 0 dBm. After connecting the LO to the receiver mixer I found a number of spurs that shouldn't have been there. Wes, W7ZOI came to my rescue explaining the importance of not driving the RF port of a balanced mixer with more than -10 dBm. After decreasing the VFO output to -10 dBm the spurs disappeared. The VFO is built into a box made of PC board material. The 10 crystals oscillators and LO mixer are built into the top half of a box made of PC material. The bottom half of the box contains the 10 BPF's and an amplifier to boost the LO output power to the desired level." ?Link http://www.ve7ca.net/Hbr200.htm read just abovesubheading 6.rf filters all the best ?reagards ?sarma vu3zmv |
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Re: uBITX Questions
In a mixer , if the carrier level is above -10dbm,? spurs do occur. we can try to reduce the level by changing the? attenusator and try . I had read this today as a comment by weshaywards.regards Sarma ? On Wed, Oct 25, 2017 at 5:02 PM, Jean-Matthieu F5RCT via Groups.Io <f5rct.jm@...> wrote: Hello ! |
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Re: uBITX Questions
Hello !
I'm sorry but the spurs are getting worse if I terminate all outputs to 50 Ohms ! If only one ouptut is activated the signal is clean ! Does someone did similar measurments on Raduino in configuration with the 3 ouputs activated ? I'm spending time on the ubitx software? (? ) the actual version is not finalized and some function as RIT VFOA/B are not yet functional. Now I updated tis software to be compatible with the latest Si5351 libraries, and it make it more simple ! 73 de F5RCT ???? |
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Re: Help with troubleshooting Bitx40 - no transmit.
#bitx40help
Amendment: *your* multimeter ... I assumed it to be a modern digital one. The old analog 'originals' measured Current - again, always - a completely different philosophy that relied on the current through the coil of the meter movement to deflect the attached pointer over its scale. The usage of the leads remained the same. 73 de ZL2DEX |
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Re: Help with troubleshooting Bitx40 - no transmit.
#bitx40help
Here's an old post on diode RF probes and AC measurements in the Bitx40 power amp:
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? ?/g/BITX20/message/22764 And the bottom paragraph here; ?? ? ?/g/BITX20/message/21941 A few other webpages on rf probes: Stephen wrote: ? > ?If your meter is set to 10A shouldn't you be plugging the leads in to COM and 10A? I think he nailed it. Jerry On Tue, Oct 24, 2017 at 06:30 pm, Arv Evans wrote:
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Re: Help with troubleshooting Bitx40 - no transmit.
#bitx40help
Point of basics: the multimeter measures *Voltage* - always! When measuring Current it is measuring the voltage dropped by its internal (small) resistor in series with whatever load you conned.. As such your Red lead (to 10A ) goes to your battery Positive, and the black lead (COM) to the Rig (BitX, the 'load') positive, and it will measure + voltages as above and display them suitably scaled as positive (+) currents.
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Re: l7805cv Gets hot!
#bitx40help
yup...it does!? I also added the external resistor On Mon, Oct 9, 2017 at 11:57 PM, Dexter N Muir <dexy@...> wrote:
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Paul Mateer, AA9GG Elan Engineering Corp. NAQCC 3123, SKCC 4628 |
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Re: Temp Monitoring
FYI it has 3 filter caps and a 6v tranzorb on the power line and a feed-thru cap on the data line... On Tue, Oct 17, 2017 at 9:35 PM, Jack Purdum via Groups.Io <jjpurdum@...> wrote:
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Paul Mateer, AA9GG Elan Engineering Corp. NAQCC 3123, SKCC 4628 |
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Re: Help with troubleshooting Bitx40 - no transmit.
#bitx40help
Here's Wayne's 100pf hack: ?
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But I think credit for that should go to Don Cantrell: ? Regarding current measurements, if things are strange I suggest backing off to something simpler. Perhaps practice measuring the current through a 100 ohm resistor from a 9v battery. I assume you are supplying 12v to the PA-PWR1 connector when attempting to transmit. > ?How do I confirm that POS and GRND are connected to the proper side of the connector (board)? With an ohmmeter. ?Make sure board ground is connected to BNC shell. ?Make sure board antenna connection is connected to BNC pin. ?And make sure there is no connection (as seen by the ohmmeter) between the two. Jerry On Tue, Oct 24, 2017 at 06:11 pm, Neris Biciunas wrote:
OK. ?So a few more facts for the puzzle.? |
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Re: Help with troubleshooting Bitx40 - no transmit.
#bitx40help
¿ªÔÆÌåÓýIf your meter is set to 10A shouldn't you be plugging the leads in to COM and 10A?On 10/24/2017 09:11 PM, Neris Biciunas
wrote:
OK. ?So a few more facts for the puzzle. |
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Re: Help with troubleshooting Bitx40 - no transmit.
#bitx40help
David? WA7NJB If you can add an RF detector probe to your test equipment inventory it might be very useful for measuring RF levels at various points in the transceiver.? There are kits for RF detector probes but they are so simple that you can easily build your own from on-line articles and schematics.? To maximize the value of an RF detector probe you do need to understand how it works and what it is trying to tell you.? Arv? K7HKL _._ On Tue, Oct 24, 2017 at 3:41 PM, Neris Biciunas <nbiciunas@...> wrote: There are many things that I don't know, and I sincerely thank all of you for the resource that is growing here in this group. |
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Re: Help with troubleshooting Bitx40 - no transmit.
#bitx40help
Neris Biciunas
OK. ?So a few more facts for the puzzle.
-One of the extra capacitors is 100 pF in parallel with L7. ?As per Wayne NB6M as written up in BitX Hacks Blog. -I tried to measure mA again, and something is really odd. First, I am running power from a battery box, 12.85v. ? All connections are Powerpoles. ?I checked the power at the power distribution block (inside the radio, behind the fuse) 12.90v. ?My multimeter is a Mastech MS8264. ?Black lead is plugged into "COM", red lead into "mA". ?The dial is set to 10 A ?DC. ?The value that I see is -1.10 A, rising slowly to -0.45 A. ?Yes, I said negative values, ?No, I don't have my wires crossed. ?What the heck! Jerry, Thanks for all of the good leads. ?It will take me bit to figure out some of them. ?A few I can respond to now. "If all you are doing is pressing the PTT button, you won't see any RF going out. On a single sideband rig, you only get RF to the antenna wen there is audio into the microphone." ? ? ? Yep, I have tried "hallooooing" into the mic - not apparent effect. "Put tape over the ends of all the extra leads coming out of that Raduino" ? ? ?My leads are pretty tidy. ?Not promising that I did't already short something, but I usually keep things pretty tidy. "Make sure your antenna connector is wired up properly. Don't laugh, it happens." ? ? ?Well, I have replaced the separate leads as supplied by HFSigs, with a short piece of tiny coax to a BNC. ?I am using the supplied connector. ?How do I confirm that POS and GRND are connected to the proper side of the connector (board)? It will take me a bit to figure out the rest of your feedback. ?Thank you very much!? |
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Re: Help with troubleshooting Bitx40 - no transmit.
#bitx40help
You're probably very close to a working rig.
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If all you are doing is pressing the PTT button, you won't see any RF going out. On a single sideband rig, you only get RF to the antenna wen there is audio into the microphone. If you don't trust your wattmeter, maybe put a 1 watt 50 ohm resistor (or 4 1/4 watt 200 ohm resistors, etc) on the antenna jack, see if they get hot when attempting to transmit. ?If transmitting 5 watts into a 1 watt resistor, don't transmit for more than a few seconds or you will cook the resistor. Be very careful as you mess around, take a break when you get tired. Put tape over the ends of all the extra leads coming out of that Raduino, don't want them to brush against anything they should not, such as the IRF510 heatsink. If the IRF510 heatsink is not electrically isolated from the IRF510 tab, don't short anything to that heatsink as it is at 12vdc. Make sure your antenna connector is wired up properly. Don't laugh, it happens. On receive, it should be on the order of 150ma (I don't remember exactly) for main bitx40 plus Raduino. With ptt pressed and no audio, it will go up a bit from there, Should see about 100 ma (within 20%) ?into the IRF510 drain (connector PA-PWR1) when ptt is pressed. If it is more than 100ma into the IRF510 with no audio into the mike, stop quickly before it smokes. If it is less, measure the dc voltage at the IRF510 gate when pressing ptt, and tell us the current into the irf510 and the voltage at the gate. Be careful if you choose adjust the 10k pot at rv1 as in the wireup instructions, it is very touchy and if you turn it up too hi the irf510 will smoke. What's worse, it's wired up backwards, so turning it counter-clockwise will increase the bias into the irf510. Safest thing is to remove power from PA-PWR1 and monitor the voltage at the IRF510 gate while fiddling with rv1 to get a feel for how it works. ?The 100ma point will be at around 3 or 4 volts, the smoking IRF510 point will be maybe 0.5v above that. Then adjust that bias back down to zero volts, connect back up PA-PWR1 to a 12v source with a 2 amp fuse, and slowly turn rv1 back up? (counterclockwise!) till get get to that magic 100ma spot. On Tue, Oct 24, 2017 at 02:41 pm, Neris Biciunas wrote:
-I have a QRP dummy load (), and the voltage measured (between ground and VRMS pin is something like 0.57) (RF power = (0.57^2)/50= .0065 watts) when the mic is keyed. |
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Re: Raduino question.
Vince Vielhaber
My bench is only good to 1GHz, unless I can figure out a way to put these scopes in series!
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Vince. On 10/24/2017 06:48 PM, Gordon Gibby wrote:
Well, I sure am grateful for people with great test equipment!!!! --
Michigan VHF Corp. |
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Re: Raduino question.
Vince Vielhaber
Disregard this, I see you found it.
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Vince. On 10/24/2017 06:46 PM, Vince Vielhaber wrote:
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Michigan VHF Corp. |
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Re: Raduino question.
Gordon Gibby
Well, I sure am grateful for people with great test equipment!!!!
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Sent from my iPhone On Oct 24, 2017, at 6:46 PM, Vince Vielhaber <vev@...> wrote: |
Jean-Matthieu F5RCT
AA9GG
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