It's Alive !
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You've been writing about this for over a week. Have you tried what has been suggested (i.e., replacing the LM386, checking the transistors, etc.)? Have you tried different sets of headphones rather than external speakers? Are the voltages on the transistors correct? Jack, W8TEE From: "wp3dx@... [SoftwareControlledHamRadio]" To: SoftwareControlledHamRadio@... Sent: Monday, April 11, 2016 3:18 PM Subject: [SoftwareControlledHamRadio] Re: It's Alive ! Hi! I played with the radio for a while yesterday and I'm having some difficulty copying other stations. I hear them very low, like "far away" , fainting.?I'm noticing a lot of the "hiss" noise that Aaron described earlier.?I double checked the antenna connection and everything is OK.? I switched to my FT817 and there were some strong signals that I could barely hear with the 49er.? No noise when I turn the radio On ?and the antenna is not connected. The noise appears right after the splash screen and it becomes louder if I increase the volume on the external speaker.? I did tried transmitting and was able to hear myself on another radio. Everything seems to be working fine except for that little issue I'm having when receiving other stations.?Any suggestions ??? I'm using a 12v battery.? Regards Norbert PS - My 49er is from ebay (vendor tianlo_go)
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Another possibility that I think I remember me doing was putting an electrolytic in backwards and that cut the audio in the next stage. We I heard that, I said: "No way...I'm too careful." Way. I had one in backwards. I replaced it and things were as they should have been. Jack, W8TEE From: "Aaron Heverin aaronhev@... [SoftwareControlledHamRadio]" To: SoftwareControlledHamRadio@... Sent: Monday, April 11, 2016 6:01 PM Subject: Re: [SoftwareControlledHamRadio] Re: It's Alive ! Norbert, One test I did make was to disconnect the speaker, plug in the headphones, and pull the DDS board and check for hiss. It was still there. The I pulled the oscillator chip - U2 (LM 602) and still had hiss. So my thinking is that the DDS board and the local oscillator are clean and the hiss is coming directly from the LM-386 or some part in the audio amplifier circuit. I'm picking up a couple of spare LM-386 chips from a friend at our club's hamfest tomorrow so I'll give a replacement a try and report back. My problem is I tend to take a lot of these electronic components at face value... meaning if they're new, they must be perfect. I've found many times that this isn't always the case.? I'm actually putting the radio together as part of a class a friend and I will be teaching at our radio club. In the past he's found several LM386 chips that have been brand new, but not very strong and the source for either distortion or hiss. We actually built an audio distribution amplifier for several operators to be able to wear headphone while working a special event like Field Day or Museum Ships Weekend. Had had a single input into the amp with three outputs... each controlled with a small LM386 amplifier. Sure enough, one of the outputs was lousy very distorted and hissy. I replaced the chip and all was well. I'm not saying that this is the cause of the hiss I'm experiencing, but without switching out a component or two, you're just guessing.? Also, on the DDS board, make sure you're feeding pin J6 on the 49-er from pin J3 on the DDS board. In case you didn't see this part in Jack's manual, it's on page 20, second paragraph. I have to admit, I missed this the first time and relied solely on the schematic for the hook-up procedure. Likewise, make sure you've got the antenna connections to the 49-er correct. If you're holding the 49-er with the sockets J2 and J4 directly in front of you, J4 will be on the left side. If you refer to the A10 in the assembly instructions, you'll see a layout of the 49-er board and then we'll both be on the same page. The center conductor for the antenna output at J4, will be the RIGHT pin, the ground connection is the left pin. Try reversing the the connection you made - if you haven't done so already and see if that brings in the signals.? On 40 right now, the band is flooded with very strong CW signals. I've got somebody at 7.050 that's about 10 over (could be W1AW for that matter). I've made several contacts with the rig this afternoon and am really pleased. In fact, I just worked K3SEW and we were both 59+. Now if only the snow and rain would stop I'd take this thing outside, throw a wire up into a tree, and make the world go away for an hour or so while I enjoy QRP CW bliss. Aaron - N2HTL On Mon, Apr 11, 2016 at 3:53 PM, Jack Purdum jjpurdum@... [SoftwareControlledHamRadio] <SoftwareControlledHamRadio@...> wrote:
Aaron
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jjpurdum