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Hi. Completed a build a few days ago, but haven't heard any signals at all, not even weak CW. There are a few heterodynes & birdies but nothing else.?
Transmit is fine into a dummy load and I can hear myself on the right Freq on a radio. Current readings are in line with the values in the instructions. I'm just using a 1/4 wave out of the window thru a 9:1 balun which I know isn't optimal but I'd expect to hear at least something.
The noise level is minimal without the antenna, and comes up strongly when I connect it. Power is 12v from a decent quality switch mode PSU. The rig is mounted in a metal case. I've checked all the connections are per the instructions - many times - and especially that the brown wire goes to the centre pin on the antenna connector.
I will try out the steps in Ashhar's video. Just wanted to know if there are any other troubleshooting tips I can try first.
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Tim
4X5TS
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Check soldering of L 1, 2 & 3
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At 12-10-2017, you wrote: Hi. Completed a build a few days ago, but haven't heard any signals at all, not even weak CW. There are a few heterodynes & birdies but nothing else.
Transmit is fine into a dummy load and I can hear myself on the right Freq on a radio. Current readings are in line with the values in the instructions. I'm just using a 1/4 wave out of the window thru a 9:1 balun which I know isn't optimal but I'd expect to hear at least something.
The noise level is minimal without the antenna, and comes up strongly when I connect it. Power is 12v from a decent quality switch mode PSU. The rig is mounted in a metal case. I've checked all the connections are per the instructions - many times - and especially that the brown wire goes to the centre pin on the antenna connector.
I will try out the steps in Ashhar's video. Just wanted to know if there are any other troubleshooting tips I can try first.
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Tim
4X5TS
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Tim, your description of the change in background noise when you attach the antenna sounds appropriate. Without the antenna connected the RX is very quiet, attach the antenna and there is a significant increase in RX noise.?
What time of the day are you listening? Here in VK we have many groups that use 40 meters in the mid to late afternoon, then again around dusk there is another increase in activity. It may be you are listening at the wrong time.
Do you have another receiver that you can use on 40 meters to compare the BitX40 with? I suppose not otherwise you wouldnt have posted the question. Raj's sugestion of checking L1,2 and 3 is good advise. Also check that the windings are not shorted together. Some of the early boards were not packed as well as later ones and some of the torroids were pushed around a bit during transport and this caused some windings to become shorted. It is easy to fix by moving the wires apart with a tooth pick or a match etc. Good luck getting it going they are a heap of fun to work with.
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Mike VK3XL
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Thanks Raj and Mike.
I did hook up a (fairly deaf) receiver to the same antenna and heard many CW and sideband QSOs, the most distant around 2000km. Went back to the BitX, and got absolutely nothing. Hopefully I'll have time later today to dive in and check the coils. I really appreciate the advice!
-- Tim 4X5TS
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Hi.
if you can, measure the frequency and output signal of the VFO and BFO.
73
?4X1LM?
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Tim,
If Tx power is normal then your issue is only with Q16, relay K2 (M1-M2 continuity) and U1 audio amp.
Check all the voltages first.
Raj
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At 12-10-2017, you wrote: Transmit is fine into a dummy load and I can hear myself on the right Freq on a radio. Current readings are in line with the values in the instructions. I'm just using a 1/4 wave out of the window thru a 9:1 balun which I know isn't optimal but I'd expect to hear at least something.
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Thanks Raj (and toda Michael!). I'm hearing CW and some weak SSB now.?
I checked the BPF coils from the underside of the board. All were electrically connected ok but L2 had come unglued somewhere along the line. I reattached it and resoldered it to the board. I also separated out the windings on all 3 coils as much as possible where they were touching. I'm still not 100% convinced the receiver is performing at it's best, but will do another compare Vs the deaf Degen DE1103 later.?
Thanks again guys.
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Tim
4X5TS
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I second Mike's opinion. There are many times here (this morning being a good example), when the band is noisy and the signals are weak. Given the current solar flux, conditions are far from optimum. If you haven't done so already, try after dark. If you are getting a noise increase when you connect the antenna, the receive chain is fundamentally working.
Brent
VE3CUS
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If you still suspect the BFP at L1,L2,L3 you might go around it.
Just AC couple the antenna into the base of Q1.
Assuming our standard 5mhz VFO, without the 7mhz BFP you will get an image
from incoming radio signals at 5+12=17mhz. ?
So twice as many radio signals to listen to!
Jerry
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On Fri, Oct 13, 2017 at 09:27 am, Tim Scrimshaw wrote:
I checked the BPF coils from the underside of the board. All were electrically connected ok but L2 had come unglued somewhere along the line. I reattached it and resoldered it to the board. I also separated out the windings on all 3 coils as much as possible where they were touching. I'm still not 100% convinced the receiver is performing at it's best, but will do another compare Vs the deaf Degen DE1103 later.?
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Jerry, I think the current lack of sunspots will create an all natural, environmentally friendly image filter. :)
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Thanks Brent. It's already after dark here ;)
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Tim
4X5TS
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I switched off the rig for an hour, and when I powered it up again, it's gone back to being totally deaf :(
So I'm thinking the BPF wasn't the problem, but working on the board temporarily fixed something else. Raj, tomorrow I'll check the relay, audio amp and transistor as you suggested.?
T.
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Tim
4X5TS
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there is usually a birdie from the DDS around 7196.? Also check the VFO drive using the fun. Sw.?? the VFO cable from the DDS is wired OK... That is Hot side brown to hot side on main board and black wire is ground.? Most likely OK since you hear your transmitted signal on another receiver. Do you hear a pop in the speaker when you press PTT switch. I would expect the audio as noise controlled by the vol pot. When you power up do you see the Sketch version like 1.1 Just some suggestions listed. 73
On Fri, Oct 13, 2017 at 1:08 PM, Tim Scrimshaw <tscrimshaw@...> wrote: I switched off the rig for an hour, and when I powered it up again, it's gone back to being totally deaf :(
So I'm thinking the BPF wasn't the problem, but working on the board temporarily fixed something else. Raj, tomorrow I'll check the relay, audio amp and transistor as you suggested.?
T.
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Tim
4X5TS
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Hi Larry,
There's plenty of audio, plenty of birdies - including one that drifts around. Just no actual signals. The frustrating thing is that after taking out the board and resoldering a BPF coil it was working for a couple of hours. And then it stopped again :(.?
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Tim
4X5TS
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Strange, When you mentioned "Works again" do you mean receiving actual stations? (then it stops?)
I have had problems with the connectors provided on this and other PCB's over the years. ? I would look at the DDS connector on the main board.? also the coils.? You may have 'through hole" problem (known as VIA) where the PCB holes are not continuous plated connection from PCB Top to PCB bottom.? (VIA meaning viaduct). ?? Try soldering the top of the coil connections and the bottom of the same connection on each coil (and be gentle)
For grins take a magnifying glass and inspect the solder connections on the coils and components.? it seem like a pain but it's not that time consuming. Check for solder bridges while your at it.
I gather these PCB's are not robotic made but human made/assembled.? if I stuffed these PCB's i'd suspect myself as well ;) Hi Hope this helps 73 WA9DOH PS do you have access to a signal generator in the 7mHZ range?
I think if you generate a strong signal on-air signal (transciver) and you have a separate? wire antenna hook to the BITX you can blow the BITX front end.
On Fri, Oct 13, 2017 at 10:19 PM, Tim Scrimshaw <tscrimshaw@...> wrote: Hi Larry,
There's plenty of audio, plenty of birdies - including one that drifts around. Just no actual signals. The frustrating thing is that after taking out the board and resoldering a BPF coil it was working for a couple of hours. And then it stopped again :(.?
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Tim
4X5TS
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Tim,
Now I conclude that there is no problem with audio stages.
Hearing birdies means everything after the first mixer is fine!
Concentrate on Q1 and Q4 amp and filters. I suspect that there is an SMD that is not soldered well
in the first bidi amp. When you heated the coil you got that lose connection going again.
Gently pressing with a finger on the first amp may show you what is not soldered properly. Sometime
SMD cap ends break off and become intermittent.
Raj
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At 14-10-2017, you wrote: Hi Larry,
There's plenty of audio, plenty of birdies - including one that drifts around. Just no actual signals. The frustrating thing is that after taking out the board and resoldering a BPF coil it was working for a couple of hours. And then it stopped again :(.
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Tim
4X5TS
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Follow the schematic and check continuity on all the BPF inductors. You might have a broken wire. No biggy, just unsolder, unwind one winding, and solder it back making sure to burn off the enamel by holding the heat until you see it boil off when you solder it in. It's also easy to check continuity all the way from the antenna to the BPF and past the BPF to the first mixer stage.? -- Ryan Flowers W7RLF
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?<-- Learn how to go digital on the BITX40
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Ryan,
With all the inputs, he also says Tx is fine which means problem is not the filter but has to be in the Q1 amp stage.
Raj
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At 14-10-2017, you wrote: Follow the schematic and check continuity on all the BPF inductors. You might have a broken wire. No biggy, just unsolder, unwind one winding, and solder it back making sure to burn off the enamel by holding the heat until you see it boil off when you solder it in. It's also easy to check continuity all the way from the antenna to the BPF and past the BPF to the first mixer stage.
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Ryan Flowers W7RLF
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?If you have a tune-able? HF RX?, hookup a piece of wire to it and try to "listen" to the BITX's VFO.? It may be out of range and/drifting.? MIKE?
Ryan,
With all the inputs, he also says Tx is fine which means problem is not the filter but has to be in the Q1 amp stage.
Raj
At 14-10-2017, you wrote:
>Follow the schematic and check continuity on all the BPF inductors. You might have a broken wire. No biggy, just unsolder, unwind one winding, and solder it back making sure to burn off the enamel by holding the heat until you see it boil off when you solder it in. It's also easy to check continuity all the way from the antenna to the BPF and past the BPF to the first mixer stage.
>
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>Ryan Flowers W7RLF
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Thanks Mike.? When the DDS shows 7.000, I'm hearing the VFO at 5.000MHz. Tuning to 7.010, the VFO is on 4.990, and at 7.020 I can hear the VFO at 4.980.? It isn't drifting.
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Tim
4X5TS
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Raj vu2zap
Brent Seres/ VE3CUS