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Re: uBitX CW bandwith
It's funny, I have been working on getting my Laserbeam set up. Yesterday I wired it up pretty much the same (minus the extra components as they were not mentioned in the set up for the LB) But I have a DPDT for the power, and switching it into the circuit, and a SPST switch for the 1-4dB gain. The only difference was that he put it before the pot, not after like I had done. So... Today I put it before the pot. It's still not right though. When I switch it into the circuit it's like the audio gets sucked out of the thing. My LED indication is all wrong too. I have also noticed that since I put it in, I have a birdy farm. I am going to have to rethink how I have it, and where I have it. I have my uBitx in an extruded aluminum case, so I might raise the board up a couple levels and get the Laserbeam right next to the volume knob so there's very little wire between the ins and outs. Right now there's too much wire. But I also need to sort out why it's not working.? When it's switched in, it's like the audio is no longer being amplified. If I switch in the +4 gain, It's just minimal audio. I have the LEDs set up on an RGB led, red being peak, Blue being Band width, and green being center freq.? |
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?B K1 Relay, RF Side
Good Evening, All.
My K1 relay was getting intermittently sticky on TX, so I decided to replace it.? I used an AXICOM with the same pinouts as the stock Hongfa.? I'm not very good at desoldering and tore up some of the pads on the board. A little finagling and everything on the DC side of the relay seems to be working. The connections labeled TX on the schematic are getting 12V, and the connections labeled RX are getting 12V when they're supposed to and 0V when they're not supposed to. ?
But it's not transmitting.? After studying the schematic for what might be a problem with the new relay install, I'm wondering what's the purpose of the RF side of K1?? It appears that when T/R is off, then the signal from the BNC connector center goes through K3 and through K1 to the first set of filters, and so on.? When T/R is high (5V from the Raduino signalling for transmitting), then K3 disconnects the received signal trace from the BNC connector.? K1 grounds the trace coming from K3.? Is this to prevent transmission RF energy from bleeding into C80, causing some potentially nasty feedback??
And what would this have to do with the rig not transmitting?? The antenna signal is getting into the receive section, because RX appears fine.? If I'd done something wrong and K1 wasn't interrupting the path from K3, then it should transmit anyway? Am I missing something? It's possible I damaged one of the delicate toroidal transformers I suppose. Any ideas will be appreciated! 73, Arvo |
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Re: UbitX no RF out SSB and CW
Oh dran!
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Any idea where the sparks came from? Any obvious scorch marks? Sounds like you bumped L8. Look at the schematic, L8 feeds 12v from PA-PWR into the left side IRF510. I have no idea what "bumped" means, but if you shorted the wire that L8 is wound with to ground somehow, that will burn out the trace between L8 and PA-PWR. It's possible you burnt the coil, does the wire look discolored? Just holding the red voltmeter probe against L8 while the black probe is on ground would not do this, because very little current would flow through the voltmeter.. With the power supply disconnected entirely, short the PA-PWR wire to ground then short each IRF510 tab to ground.? This is to make sure any caps are discharged. Then set the DVM to the lowest ohms scale and measure ohms from PA-PWR? to each IRF510 tab in turn.? Both tabs should be close to zero ohms to PA-PWR. If one reads a lot more than zero ohms then either the coil (L8 or L9) or the traces got burned. A scorched trace could be easily repaired by soldering down a piece of wire. I doubt you blew the IRF510's or any other semiconductors. The gates should not be zero volts when you are transmitting, should be about 4 volts. ff they were zero volts when transmitting, then that was your original problem Otherwise the rig was working. Might be a good idea to lug it off to a local ham club, explain your adventure to some of the others attending see if somebody there is curious enough about the uBitx? to look it over with you and show you the ropes. Jerry On Wed, Aug 22, 2018 at 05:37 PM, Evan Clark (OSC) wrote: Ok, crap. I WAS measuring 12v at the tabs and 0v at the gates. BUT I think I bumped the inductor in front of the left final. Puff of smoke, a few visable sparks. Now measuring .84 volts either tab. Feeling quite disheartened. |
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Re: UbitX no RF out SSB and CW
Drain voltage dropped to 10 mv, now slowly increasing at 50mv On Wed, Aug 22, 2018 at 5:37 PM Evan Clark (OSC) <evanclarkie@...> wrote:
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Re: UbitX no RF out SSB and CW
Ok, crap. I WAS measuring 12v at the tabs and 0v at the gates. BUT I think I bumped the inductor in front of the left final. Puff of smoke, a few visable sparks. Now measuring .84 volts either tab. Feeling quite disheartened. On Wed, Aug 22, 2018 at 5:21 PM Dexter N Muir <dexy@...> wrote: I was thinking, Jerry, with Gate at 0V, Tab to either 0 or Gate would be 12V - *and* no RF out. :) |
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Re: UbitX no RF out SSB and CW
Dexter, welcome to the asylum.
A data sheet for the IRF510 would come in handy so you can identify source,gate and drain pins.? As Jerry stated, the tab is also connected to the drain, although he choose an 'alternate' spelling. (Jerry is indeed a team player, 'there is no I in dran') Best of luck with the uBITX, Gary |
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Re: UbitX no RF out SSB and CW
Evan,
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Not a stupid question.? All voltages are relative.?? In most cases, unless otherwise stated, relative to ground. So black lead on ground, red lead on one of the gates. Same goes for looking at the voltage on the IRF510 mounting tabs, that's relative to ground too. If you see 12v on your meter both when looking at the IRF510 tabs and when looking at the IRF510 gates relative to the +12 supply, that means they are probably both at 0 volts relative to ground. And that's bad. The IRF510 tabs should be 12v relative to ground whenever power is on. Each gate should be about 4v above ground when the transmitter is keyed. The gates can be? different, but should both be close to 4v. Do not jump ahead and try adjusting the gate voltage without understanding the correct procedure. Otherwise you almost certainly will blow the IRF510's due to excessive drain current. Jerry On Wed, Aug 22, 2018 at 04:29 PM, Evan Clark (OSC) wrote:
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Re: UbitX no RF out SSB and CW
Sorry for this, all, but just glimpsed this exchange: Evan, have you ANY electrical knowledge at all? You seem to be too junior in Hamdom to realize that a Bitx of any sort requires that much background at least. But here goes: |
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Re: Intermodulation Performance
¿ªÔÆÌåÓýAllison: ? So, then, are bandpass filters the only option? Are there in-band spurs? ? David A Posthuma, WD8PUO ? From: [email protected] <[email protected]> On Behalf Of ajparent1/KB1GMX ? David,
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Re: UbitX no RF out SSB and CW
Jerry, I'm still a little confused. When measuring the voltage on the gate for example, am I putting one end on the power input and one on the gate pin of the final? Sorry for such a noobish question. If that is the case, I'm reading 12 volts on the gate as well as the tabs. On Wed, Aug 22, 2018 at 3:53 PM Jerry Gaffke via Groups.Io <jgaffke=[email protected]> wrote: Do you see 12v on the tabs of the two IRF510's? |
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Re: UbitX no RF out SSB and CW
Do you see 12v on the tabs of the two IRF510's?
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You don't have to key the transmitter to see this, just have the receiver running. When you key the transmitter, the IRF510 gates rise up from ground to turn things on. What is the gate voltage at each IRF510 when you key the transmitter? You can make these measurements with a DC voltmeter. See 12v on the tabs (drans) of the IRF510. Something like 4v on the gates, but only when transmitting Jerry On Wed, Aug 22, 2018 at 03:30 PM, Evan Clark (OSC) wrote: orry if the last bit of the previous post was phrased oddly. I have connected the brown wire on the power in to the red one, so I am getting 12v to the finals. I now have 12v between pins 1 and 2 as well as 2 and 3. I'm still not seeing even a budge on the power meter, though. |
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Re: UbitX no RF out SSB and CW
Sorry if the last bit of the previous post was phrased oddly. I have connected the brown wire on the power in to the red one, so I am getting 12v to the finals. I now have 12v between pins 1 and 2 as well as 2 and 3. I'm still not seeing even a budge on the power meter, though. On Wed, Aug 22, 2018 at 2:55 PM Evan Clark (OSC) <evanclarkie@...> wrote:
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Re: Intermodulation Performance
Iz oos,
Its rare that distortion is heard on frequency. Is the guy 3khz up or down from you that would like to not hear you and you sputter and splatter. So with the good radio listen to your audio then flip its sideband and listen for stuff likely unintelligable and then move up or down and listen.?? Did this onece on 6M (deserted part of the band) to prove a point tto someone that? felt it was great ausio even though he had the knobs set to 11 on the scale of 10. My commercial 6M rig if I run the audio up the image on the SA gets wide yet no one on frequency hears much other than, its louder.? If I add over driving the power amp its the same!? However at the extreme tested on the air one time The band width at 15db down was 60khz and yet the guy maybe 10 miles away was sounds great and he even knows my voice from club meetings. Good audio reports are very misleading about all the stuff their receiver is filtering out but the other poor guy trying to share the band is not enjoying it. Allison |
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Re: UbitX no RF out SSB and CW
Ok I may be onto something. I removed the DC connector and opted for Anderson Power Poles for battery power usage. I did not do the proper research apparently (took 5 seconds to look at the wireup). In my swap, I connected the red to red and black to black. This left the brown wire (PA power) unconnected... not sure what my thought process was there. Anyways, I have not had 12 volts on the finals. Despite this, I still have 12 volts on the finals. On Wed, Aug 22, 2018 at 2:26 PM Jerry Gaffke via Groups.Io <jgaffke=[email protected]> wrote: Do a thorough visual inspection of the power amp, everything from Q90 out to the antenna jack. |
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Re: Intermodulation Performance
David,
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Re: 80 meter bandpass filter
Yes ...Since the relays at input and output are released and need be operated to tie to final/antenna, I just tack soldered some short pigtails to SMB connectors thence to TR502/7L13 JimOn Wed, Aug 22, 2018 at 12:12 PM, Kees T <windy10605@...> wrote: Jim, |
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Re: UbitX no RF out SSB and CW
Do a thorough visual inspection of the power amp, everything from Q90 out to the antenna jack.
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Including the antenna jack. The toroids and hand wound and installed by hand. A bad solder job due to enamel remaining on the magnet wire could do this, you could check for that with an ohmmeter. Or a broken wire due to jostling when shipped Try hooking a 50 ohm dummy load and wattmeter between T11 pin 5 and ground. That way we go around the transmit low pass filters and the relays at KT1,2,3 that select one of the filters. Jerry On Wed, Aug 22, 2018 at 02:20 PM, Jerry Gaffke wrote: I would not just randomly replace stuff. |
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Re: UbitX no RF out SSB and CW
I would not just randomly replace stuff.
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You have dozens of parts to suspect. And it worked when shipped. Do you have 12v applied to the IRF510's when transmitting? You should see 12v to ground on the tabs of the IRF510's when transmitting. Could be as simple as not having 12v wired to the PA-PWR pin of that 3 pin uBitx connector as shown in the WireUp diagram on hfsignals.? You should have a 50 ohm dummy load hooked up when testing the transmitter. Output is typically 10 watts, but if you only use it for short periods at less than 50 percent of the time, a 5 watt dummy load won't get too hot. I doubt it will damage anything to test the transmitter without a dummy load, but it could. Jerry On Wed, Aug 22, 2018 at 02:06 PM, Evan Clark (OSC) wrote:
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Arvo W0VRA
David Posthuma
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