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View Full Version : BitX20 almost done...



N2CHX
12-25-2013, 12:08 PM
I started putting it together the other day. Good thing I have a lot of spare parts and such, because it was missing some things and I have to cobble together some mods. Anyway, this version is supposed to put out 12-15 watts, not 6, so if I can get it done then maybe I'll have a QSO or two next week. Today is gonna be lazy, tomorrow is gonna be lazy but I have to work Friday and Saturday I have a wedding to attend, so...

K7SGJ
12-25-2013, 02:19 PM
I started putting it together the other day. Good thing I have a lot of spare parts and such, because it was missing some things and I have to cobble together some mods. Anyway, this version is supposed to put out 12-15 watts, not 6, so if I can get it done then maybe I'll have a QSO or two next week. Today is gonna be lazy, tomorrow is gonna be lazy but I have to work Friday and Saturday I have a wedding to attend, so...

I'm sure that wherever the wedding is being held, ac outlets for your soldering equipment will be available. Good God Girl, were talking ham radio, here.

N8YX
12-26-2013, 06:16 PM
What are you going to use for a case, Kelli?

I think one of the locals has that rig. I'm due for a visit to his place soon so I'll check it out.

N2CHX
12-26-2013, 08:49 PM
What are you going to use for a case, Kelli?

I think one of the locals has that rig. I'm due for a visit to his place soon so I'll check it out.

I'm not. This is the second kit I've bought in the last year that I wish I hadn't. Like the rockchip that was unstable as fuck, this thing is just horrid. I've wasted the last two days trying to get it to work right and I've just had it. Now that I no longer work in the field, I have no desire or patience to work on shit that should just work. No, there were no solder bridges (went over it 100 times), everything was put together according to the book, and it was just horridly unstable and terribly weak receive. So I'm done with it. I have zero desire to work on electronics anymore. Everyone and their brother asks me to work on this, fix this, fix that, fix my computer, yada yada and after 20 years of this, I'm pretty damn sick of fixing shit.

So... until I get an out of the box radio that just fucking works and I can enjoy instead of wasting 20 hours troubleshooting, I'm done. Over and out.

N8YX
12-26-2013, 08:59 PM
That rig is direct-conversion, correct?

N2CHX
12-26-2013, 09:02 PM
That rig is direct-conversion, correct?

Yes. It *should* be a simple fix. It's not rocket science. I just zero patience right now.

N8YX
12-26-2013, 09:23 PM
SWAGging here...but:

1) I'm assuming the LO is some form of DDS which is controlled by a PIC or similar embedded controller that outputs a serial data stream to the device. How does the supply voltage to the DDS look in terms of ripple and jitter?

2) Look at the output of the DDS with a scope. Is it within acceptable limits?

3) If the output appears slightly low in amplitude, what happens to the output waveform if you disconnect the DDS from the bandpass filter network and terminate it with a resistance equal to the input impedance of the filter?

Link a schematic to this post and let me examine it further, if you try the above and it sheds no light on the problem.

N2CHX
12-26-2013, 09:32 PM
SWAGging here...but:

1) I'm assuming the LO is some form of DDS which is controlled by a PIC or similar embedded controller that outputs a serial data stream to the device. How does the supply voltage to the DDS look in terms of ripple and jitter?

2) Look at the output of the DDS with a scope. Is it within acceptable limits?

3) If the output appears slightly low in amplitude, what happens to the output waveform if you disconnect the DDS from the bandpass filter network and terminate it with a resistance equal to the input impedance of the filter?

Link a schematic to this post and let me examine it further, if you try the above and it sheds no light on the problem.

Local oscillator is free-running @ 3.8-4.8 mHz. The BFO is 10 mHz. No PIC's, no fancy shit. RX output was low and there was a lot of scratchiness in it, and voltages were jumping all over the place with no rhyme or reason for it. It's probably something simple, but here's the deal... I'm a Mom of three at home. I work full time and run a side business. I just don't have the time or patience for such things anymore. I would home-brew completely if I had the time. I don't, so as a compromise between spending $$ and spending a lot of time home-brewing I bought a shitty kit from India. I can tell you the board isn't exactly robust and that's probably half the problem, if not THE problem. There are probably places where the board isn't plated through properly.

I. Just. Have. No. Patience. For. That.

I want to enjoy ham radio -- the on the air aspect of it -- not spend days I don't really have, to fix some shitty kit that may or may not work well anyway. There are some things I am willing to spend time on. This isn't one of them. I want to get on the air, not spend copious amounts of time troubleshooting a piece of crap.

N8YX
12-26-2013, 09:45 PM
Link a schematic of your actual kit into this thread. I want to check it.

I found the following which shows a DDS input for the tuning oscillator and an 11MHz BFO:

http://ic.pics.livejournal.com/bitx20a/12755134/7438/7438_original.gif

WØTKX
12-27-2013, 08:49 AM
AC0KC, a good pal of mine, just built a "son of the softrock" SDR, and it didn't work very well. Quite deaf on RX.

Took him a few days to find a solder problem on an op amp. It looked good and tested fine with the ohm meter.
But with current running thru it, the voltage was off on the op amp. Total PITA. Whew.

I don't have much time to fix stuff, and when I do, it's for the brokedown palace, or computer stuff. ;)

N2CHX
12-27-2013, 09:08 AM
Link a schematic of your actual kit into this thread. I want to check it.

I found the following which shows a DDS input for the tuning oscillator and an 11MHz BFO:

http://ic.pics.livejournal.com/bitx20a/12755134/7438/7438_original.gif

I'll have to scan it. I bought it from India. It's not like any other BitX circuits I've seen. All 2N3904 transistors, no FET's. But honestly, I just don't care at this point. I've got my eye on an Icom 730.

N2CHX
12-27-2013, 09:12 AM
AC0KC, a good pal of mine, just built a "son of the softrock" SDR, and it didn't work very well. Quite deaf on RX.

Took him a few days to find a solder problem on an op amp. It looked good and tested fine with the ohm meter.
But with current running thru it, the voltage was off on the op amp. Total PITA. Whew.

I don't have much time to fix stuff, and when I do, it's for the brokedown palace, or computer stuff. ;)

Oh yeah, one solder bridge and you're done. That's why I spent most of yesterday going over the board and making sure everything was right. I don't have much time to fix stuff either. I rarely spend any time on anything other than my kids, this house or work stuff. If I'm on here or FB it's shorties here and there in between brainstorms or working on coding. I gifted myself the time to get that radio up and running. I've built hundreds of projects between personal and work related stuff and these last two, kits, are the most frustrating things I've ever worked on. Who's got time for that? Not me. I'd rather actually be on the air.

NY4Q
12-27-2013, 03:06 PM
I've been pondering getting the Genesis G11 and sling it together. Y'unz seen it?

http://www.genesisradio.com.au/

N8YX
12-27-2013, 03:53 PM
If that thing had an optional control head I would be very interested.

As it stands, G6LBQ's Multiband BitX has piqued my interest as a bicycle mobile rig. I think I'm going to pick one up along with a smallish LDG tuner then build the whole thing into a waterproof enclosure which will fit into a Topeak DX saddlebag. A 12v, 10A gel cell should fit in the rearmost part of the bag and a portable solar array could charge the battery at a rest stop.

If I can get something that covers 10-12-15-17-20M TX and from 14-30MHz RX, that would serve my purposes better than a full-blown 9-band rig. The 102" whip I'm planning to use on the bike isn't going to load up all that well on frequencies below 20M.