Ah thanks for the post, I thought I had a fault! ?Now I know I'll get used to it as it does make sense! ?

73 de Mike, G0JXX

I asked the same question. ?It looks like you can inject a signal into the mic input and then use an outboard CW filter on receive. ?It might be simple to build a 1kHz sine oscillator using a few discrete components, a few circuits on Facebook?

73 de Mike, G0JXX

I agree. Some of the below displays may be somewhat different as there will be harmonics at most points before the low pass filter.

I found the web page I was looking for.

This should give plenty of information to isolate a problem in the pa.

Leonard

Rule of thumb says the scope bandwidth should be about 10 times the signal displayed

I suppose I could mostly agree with that, though a 20 mhz analog scope should be good enough to diagnose this problem.

I assume his transmitter is running at 14 mhz. If you want to check signal shapes to see if there's a harmonic present at 14*3 or 14*7 mhz, then yes. ?If you just want to see if a 14 mhz signal is present and get a fair idea of the amplitude, then a scope with a bandwidth of 14 mhz or more is sufficient. ?A 14 mhz signal through a device with 14 mhz of bandwidth will be 3db down. At 3db down the displayed voltage on the scope will be down by sqrt(2), if it was really 1.414 volts pk-pk the scope would show 1 volt pk-pk. ?Good enough.?

Now if we're talking a cheap digital scope claiming a 20 mhz sample rate, then yes, likely not good for looking at a signal much faster than 2 to 4 mhz. ?Sample rate and bandwidth are two different things. ?A good quality digital scope will sample at 10 times the bandwidth of the vertical amplifier, the cheaper ones might limit the bandwidth to 5 times the sample rate.

Jerry, KE7ER

?

I would be real suspicious of T1 or T2 not phased right if the problem is in the pa. Also, a mike input of 25-50 mv's is plenty. With 25-50 mv's into the mike jack you should get 1 volt or so at the input to the pa when the 2 boards are connected together. I would guess you are over driving the mike input trying to correct for a different problem. I have a series of pictures at the common points for the pa board but I'll have to put them into web page format so it will take me a couple of days. In the mean time, try checking the linear as shown in the video. You should get meaningful information with your scope.

Leonard

This video is from an older version 3 linear

but it should perform about the same. It shows about 1-2 volts in will drive it well. Also it shows a couple of different ways of looking at it when you get to fancier equipment. This was cw testing so your scope would need to be around 50 mhz or more to accurately display the cw signal. Rule of thumb says the scope bandwidth should be about 10 times the signal displayed.

Leonard raises a good point. ?I assume Mark is supplying audio at an appropriate level when measuring power out, and not just measuring residual carrier. ?The standard Raduino firmware should generate an audio tone on one of the digital outputs so we have a known audio level to conduct tests like this with.

Yes, could look at the modulation envelope. ?I was concerned that if the max sweep speed was 0.5us/div, the bandwidth would likely be down around 5 MHz. ?But if he really has a 20 mhz scope, then he's all set.

What's the gain of the Q1 stage work out to? ?With a 2v pk-pk signal going in, anyone care to guess what ac signal he should see at he gate of Q2?

Jerry, KE7ER

When testing the modulation envelope the scope sweep speed should be set around 1ms per division so the modulation envelope and not the usb frequency will be displayed. With the scope set at around 1 usec and no modulation, the carrier balance would be set to minimum out. You should end up with less than 1 volt displayed. Most of the ones I've worked on was between 250 mv and 500mv.

Leonard

Are these the correct sources for the most recent Raduino sketch for the Bitx40 and for the Si5351 library?

https://github.com/afarhan/bitx40

https://github.com/etherkit/Si5351Arduino

I noticed that there are a number of forks of the Si5351 library and it might explain the following errors when trying to verify raduino.ino:

raduino.ino: In function ‘void calibrate()’:
raduino.ino:281:91: error: no matching function for call to ‘Si5351::set_freq(long long int, long long unsigned int, si5351_clock)’
raduino.ino:281:91: note: candidate is:
In file included from raduino.ino:38:0:
/home/paul/sketchbook/libraries/Si5351/si5351.h:285:10: note: uint8_t Si5351::set_freq(uint64_t, si5351_clock)
? uint8_t set_freq(uint64_t, enum si5351_clock);
????????? ^
/home/paul/sketchbook/libraries/Si5351/si5351.h:285:10: note:?? candidate expects 2 arguments, 3 provided
raduino.ino: In function ‘void setFrequency(long unsigned int)’:
raduino.ino:312:75: error: no matching function for call to ‘Si5351::set_freq(long long unsigned int, long long unsigned int, si5351_clock)’
raduino.ino:312:75: note: candidate is:
In file included from raduino.ino:38:0:
/home/paul/sketchbook/libraries/Si5351/si5351.h:285:10: note: uint8_t Si5351::set_freq(uint64_t, si5351_clock)
? uint8_t set_freq(uint64_t, enum si5351_clock);
????????? ^
/home/paul/sketchbook/libraries/Si5351/si5351.h:285:10: note:?? candidate expects 2 arguments, 3 provided
raduino.ino:315:75: error: no matching function for call to ‘Si5351::set_freq(long long unsigned int, long long unsigned int, si5351_clock)’
raduino.ino:315:75: note: candidate is:
In file included from raduino.ino:38:0:
/home/paul/sketchbook/libraries/Si5351/si5351.h:285:10: note: uint8_t Si5351::set_freq(uint64_t, si5351_clock)
? uint8_t set_freq(uint64_t, enum si5351_clock);
????????? ^
/home/paul/sketchbook/libraries/Si5351/si5351.h:285:10: note:?? candidate expects 2 arguments, 3 provided
raduino.ino: In function ‘void setup()’:
raduino.ino:589:48: error: no matching function for call to ‘Si5351::init(int, long int)’
raduino.ino:589:48: note: candidate is:
In file included from raduino.ino:38:0:
/home/paul/sketchbook/libraries/Si5351/si5351.h:283:7: note: void Si5351::init(uint8_t, uint32_t, int32_t)
? void init(uint8_t, uint32_t, int32_t);
?????? ^
/home/paul/sketchbook/libraries/Si5351/si5351.h:283:7: note:?? candidate expects 3 arguments, 2 provided
raduino.ino:601:62: error: no matching function for call to ‘Si5351::set_freq(long int, long long unsigned int, si5351_clock)’
raduino.ino:601:62: note: candidate is:
In file included from raduino.ino:38:0:
/home/paul/sketchbook/libraries/Si5351/si5351.h:285:10: note: uint8_t Si5351::set_freq(uint64_t, si5351_clock)
? uint8_t set_freq(uint64_t, enum si5351_clock);
????????? ^
/home/paul/sketchbook/libraries/Si5351/si5351.h:285:10: note:?? candidate expects 2 arguments, 3 provided

开云体育

2v pk-pk sounds about right to me, though I don't really know.

Output pk-pk voltage should be about the same with or without the filter and that seems to be pretty much the case, you have trouble elsewhere.

I assume you have the bias voltage into the gate of that IRF510 set correctly, what is your current draw when the transmitter is quiet?

I'd be really curious what the DC and AC voltages are on the IRF510 gate.

With the output filter and the filter at the IRF510 gate both removed, this amp should be very broadband.

Maybe create a source of a couple MHz at 2v pk-pk and feed that into the amp, that might let you better see what's going on with a slow scope.

Might be able to use your VFO, adding a bunch of caps to lower the frequency.

Weird that you can tell the amplitude "is pushing 2v pk-pk" if the scope is otherwise too slow to display it, a simple diode RF probe might be

a more suitable instrument to measure RF voltages. ? ?

Hopefully somebody out there more familiar with Sunil's design can give you some better pointers.

Jerry, KE7ER