Re: Low Audio, CP2 Proximity sensitivity
I'm sure Farrukh and Dennis can give a more precise answer, but I'm pretty sure it's because you put the white smoke back in.
Jack, W8TEE
From: "Aaron Heverin aaronhev@... [SoftwareControlledHamRadio]"
To: SoftwareControlledHamRadio@...
Sent: Thursday, April 28, 2016 10:33 PM
Subject: Re: [SoftwareControlledHamRadio] Re: Low Audio, CP2 Proximity sensitivity
?
Gents, This is indeed a puzzler.. and there's something else I want to bring up on the odd chance that somehow it's related. As you know, I blew out my original D882 output transistor. While I was waiting for the replacement, I reset the peak-to-peak voltage output of R1 so that I wouldn't smoke the replacement transistor. I also did some testing on the LM386 chip to see if I could improve the quality of the audio as a whole, and if needed, build an outboard audio circuit independent of the 49-er. The results of this testing aren't in yet... and of course, my 49-er was suffering from very low audio. Yesterday, the replacement D882s arrived from Tayda Electronics. I constructed a pretty nifty heatsink for it... making it large enough to dissipate heat, but not so horribly ugly and out-of-place looking. With my mod in place, I fired up the radio.?
Now I think I'm a pretty level-headed guy even though I tend to get a little skittish about throwing that power switch for the first time because I don't like letting the smoke out. I also don't always completely understand how a circuit works without dozens of hours of study and a little help from my very knowledgable friend when I get stuck. But darned if when the 49-er came up it sounded different! I mean, it was loud! Signals were all over the place and I could actually hear band noise for the first time. I actually made a few contacts with it even though NOW I was only putting out 3 watts of power. Good thing. :-)
So my question is this... is there a logical explanation why the D882 would affect the audio output - or the signal output/input - of the 49-er? I see that the collector (pin 2) of the D882 is tied to C14, then L4 to pin 1 of the antenna connector - which would be the center conductor of a piece of coax. The base (pin 3) of the D882 is getting fed from the preamp circuit through C-15 with D3 tied to ground. I'm just sitting here scratching my head because I'm stumped on trying to completely understand the preamp and final part of the circuit and how it could possibly be tied to the RX RF section and the audio chain. But perhaps it's not the audio chain at all that's causing the "low audio" problems folks are having. If the D882 is in line with the antenna jack, and it's got problems, it stands to reason that the incoming signals are weak and that's what is causing the "low audio."
My 49-er is an entirely new radio. It's darned loud now. I'm just trying to get my hand around a logical reason for it.?
Aaron - N2HTL
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Re: Low Audio, CP2 Proximity sensitivity
Gents, This is indeed a puzzler.. and there's something else I want to bring up on the odd chance that somehow it's related. As you know, I blew out my original D882 output transistor. While I was waiting for the replacement, I reset the peak-to-peak voltage output of R1 so that I wouldn't smoke the replacement transistor. I also did some testing on the LM386 chip to see if I could improve the quality of the audio as a whole, and if needed, build an outboard audio circuit independent of the 49-er. The results of this testing aren't in yet... and of course, my 49-er was suffering from very low audio. Yesterday, the replacement D882s arrived from Tayda Electronics. I constructed a pretty nifty heatsink for it... making it large enough to dissipate heat, but not so horribly ugly and out-of-place looking. With my mod in place, I fired up the radio.?
Now I think I'm a pretty level-headed guy even though I tend to get a little skittish about throwing that power switch for the first time because I don't like letting the smoke out. I also don't always completely understand how a circuit works without dozens of hours of study and a little help from my very knowledgable friend when I get stuck. But darned if when the 49-er came up it sounded different! I mean, it was loud! Signals were all over the place and I could actually hear band noise for the first time. I actually made a few contacts with it even though NOW I was only putting out 3 watts of power. Good thing. :-)
So my question is this... is there a logical explanation why the D882 would affect the audio output - or the signal output/input - of the 49-er? I see that the collector (pin 2) of the D882 is tied to C14, then L4 to pin 1 of the antenna connector - which would be the center conductor of a piece of coax. The base (pin 3) of the D882 is getting fed from the preamp circuit through C-15 with D3 tied to ground. I'm just sitting here scratching my head because I'm stumped on trying to completely understand the preamp and final part of the circuit and how it could possibly be tied to the RX RF section and the audio chain. But perhaps it's not the audio chain at all that's causing the "low audio" problems folks are having. If the D882 is in line with the antenna jack, and it's got problems, it stands to reason that the incoming signals are weak and that's what is causing the "low audio."
My 49-er is an entirely new radio. It's darned loud now. I'm just trying to get my hand around a logical reason for it.?
Aaron - N2HTL
?
Keep us posted...this is a puzzle...
Jack, W8TEE
?
In the interim, I've ordered another forty-9er kit from a different supplier. I'm going to check each component and compare the two boards. I'll build the new one and try and still figure out what's wrong with the other..
Steve NS3L
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Re: Low Audio, CP2 Proximity sensitivity
Keep us posted...this is a puzzle...
Jack, W8TEE
From: "ns3l@... [SoftwareControlledHamRadio]"
To: SoftwareControlledHamRadio@...
Sent: Thursday, April 28, 2016 6:43 PM
Subject: Re: [SoftwareControlledHamRadio] Re: Low Audio, CP2 Proximity sensitivity
?
In the interim, I've ordered another forty-9er kit from a different supplier. I'm going to check each component and compare the two boards. I'll build the new one and try and still figure out what's wrong with the other..
Steve NS3L
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Re: Low Audio, CP2 Proximity sensitivity
In the interim, I've ordered another forty-9er kit from a different supplier. I'm going to check each component and compare the two boards. I'll build the new one and try and still figure out what's wrong with the other..
Steve NS3L
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Re: Low Audio, CP2 Proximity sensitivity
Hi Steve. My understanding is that the 2SK30A is installed as a TX Mute transistor.? Aaron - N2HTL
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Aaron,
If I'm not mistaken isn't the 2SK30A "Q1" the preamp in the audio chain? When I looked over the circuit diagram then and looked up the 2SK30A, it's listed as a pre-amp.. Just thumbing around at this point. Have you checked to see that Q1 is working correctly? If It's low or bad, and since it's prior to the LM386 is there any possibility this could be part of the problem?
Steve NS3L?
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Re: Low Audio, CP2 Proximity sensitivity
I'm still thinking some component is bad or perhaps a break somewhere in the board. There are just too many others who have the rig working for it not to work adequately. With your external amp, probe backwards from the 386 input and see if there's a point where you get signal amplification. Clearly you can only go back so far, but it's worth a shot.
Jack, W8TEE
From: "Aaron Heverin aaronhev@... [SoftwareControlledHamRadio]"
To: SoftwareControlledHamRadio@...
Sent: Monday, April 25, 2016 12:35 AM
Subject: Re: [SoftwareControlledHamRadio] Re: Low Audio, CP2 Proximity sensitivity
?
Evening all. I wanted to toss this out in order to get some feedback on the low audio/hiss issue from the 49-er.
I put together a basic amplifier using a spare LM-386 chip. Once the amp was finished, I powered it with a 9-volt battery and fed it with audio from my iPod. When it first powered up, I thought I had hooked something up incorrectly on the breadboard because I didn't hear anything... no hiss, no noise, no popping... just plain silence. Fed the circuit some audio from the iPod and was completely surprised. It sounded really good! I was using an 8 ohm small car stereo speaker I had laying around the shop. The bass response was pretty good and I was getting a really comfortable listening level. I noticed that you can't turn the volume up too high or else it will distort, but I wasn't going for sound to blast me out of the room... just a good level and CLEAN signal.
Next, I went to the 49-er and pulled the LM-386 chip out because I wanted to bypass the 49-er's audio output entirely. Following the schematic, I hooked a ground lead from the "SPK" ground to my amp, then I took a probe and tapped the negative side of CP10 which, unless I'm missing something, is the input to the LM-386 on the 49-er. Immediately, I started hearing the signals of 40m... but they were incredibly faint! I raised the volume on my amp as high as it would go and tapped CP10 once again. The volume was a bit higher... but still so darned low that if you were to breath too hard you'd never hear it.
So at this point, my conclusion is that the audio going to the LM-386 on the 49-er is just too low for it to be amplified to any good level... meaning it may need a preamp of some kind. The audio coming from my iPod was MUCH higher and was able to hit the LM-386 with enough gain to be amplified to a good level. Not so with the audio from the 49-er. I'm going to try connecting my Radio Shack mini amplified speaker directly to CP10 and ground and see what happens there. I suspect that if I get good audio using this hookup, then it should get pretty close to proving that the signal from the 49-er is just not powerful enough to be amplified by the LM-386 without a mod.?
Hopefully someone else can chime in one this.
Aaron - N2HTL
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Re: Low Audio, CP2 Proximity sensitivity
Aaron,
While my 49er has some transmitter problems, the receiver audio level is fine. I am moderately hard of hearing, so a low audio condition would effect me even more than a person with normal hearing, so I don't think it is a design problem that is causing your low audio.? What I have found is that the antenna being used effects the perceived receiver sensitivity and audio levels considerably.? I have an 8 band Hustler vertical with radials that works fine with the receiver.? I also have 80/40 meter Butternut vertical without radials that when used, the receiver is plagued by broadcast band interference that masks the actual 40 meter signals.? But in either case, the audio is OK using a Yamaha CM500 headset.? The sidetone audio is earsplitting loud, however, that is unrelated to the actual received signal audio level.
As I had mentioned once before, I have some harmonic and dirty signal problems that I was able to confirm on a digital spectrum analyzer.? I only have about 400 mW of dirty looking RF output that has harmonics that are only about 30 db down from the 40 meter signal.? I am still investigating that problem but I don't suspect it is a design problem.? The 49er that I am using is one that I had started modifying for another project, then changed directions mid-mod when this QST article came along, so I suspect I have something jumbled up somewhere in the transmitter chain.
Good luck with your troubleshooting.
Dave, W0DF
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Re: Low Audio, CP2 Proximity sensitivity
Interesting....I thought it was my head cold that caused the low audio output. I built an audio signal tracer a while ago that uses a 386 and that output is great....going back to the bench to look at this 49'er audio output again.
don
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Re: Low Audio, CP2 Proximity sensitivity
Aaron,
If I'm not mistaken isn't the 2SK30A "Q1" the preamp in the audio chain? When I looked over the circuit diagram then and looked up the 2SK30A, it's listed as a pre-amp.. Just thumbing around at this point. Have you checked to see that Q1 is working correctly? If It's low or bad, and since it's prior to the LM386 is there any possibility this could be part of the problem?
Steve NS3L?
|
Re: Low Audio, CP2 Proximity sensitivity
Evening all. I wanted to toss this out in order to get some feedback on the low audio/hiss issue from the 49-er.
I put together a basic amplifier using a spare LM-386 chip. Once the amp was finished, I powered it with a 9-volt battery and fed it with audio from my iPod. When it first powered up, I thought I had hooked something up incorrectly on the breadboard because I didn't hear anything... no hiss, no noise, no popping... just plain silence. Fed the circuit some audio from the iPod and was completely surprised. It sounded really good! I was using an 8 ohm small car stereo speaker I had laying around the shop. The bass response was pretty good and I was getting a really comfortable listening level. I noticed that you can't turn the volume up too high or else it will distort, but I wasn't going for sound to blast me out of the room... just a good level and CLEAN signal.
Next, I went to the 49-er and pulled the LM-386 chip out because I wanted to bypass the 49-er's audio output entirely. Following the schematic, I hooked a ground lead from the "SPK" ground to my amp, then I took a probe and tapped the negative side of CP10 which, unless I'm missing something, is the input to the LM-386 on the 49-er. Immediately, I started hearing the signals of 40m... but they were incredibly faint! I raised the volume on my amp as high as it would go and tapped CP10 once again. The volume was a bit higher... but still so darned low that if you were to breath too hard you'd never hear it.
So at this point, my conclusion is that the audio going to the LM-386 on the 49-er is just too low for it to be amplified to any good level... meaning it may need a preamp of some kind. The audio coming from my iPod was MUCH higher and was able to hit the LM-386 with enough gain to be amplified to a good level. Not so with the audio from the 49-er. I'm going to try connecting my Radio Shack mini amplified speaker directly to CP10 and ground and see what happens there. I suspect that if I get good audio using this hookup, then it should get pretty close to proving that the signal from the 49-er is just not powerful enough to be amplified by the LM-386 without a mod.?
Hopefully someone else can chime in one this.
Aaron - N2HTL
?
Hi Frank,
Yes I got the parts and used them.. Thanks very much..
As far as everything else I'm going to change parts one by one if needed..
Steve NS3L..
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Hi,
With the plethora of Ebay kit sources and problems with questionable parts quality from some, can anyone recommend a kit provider that you like?
73 Dave KF5OCP
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Re: Low Audio, CP2 Proximity sensitivity
Hi Frank,
Yes I got the parts and used them.. Thanks very much..
As far as everything else I'm going to change parts one by one if needed..
Steve NS3L..
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Re: Low Audio, CP2 Proximity sensitivity
Steve:
???? I replaced most of the?Forty-9er components with my own parts.? The?parts in the kit?just didn't appear to be of high quality.? With exception of the D882,?only a few of the supplied parts were installed.? It worked very well from the start.? The audio was low, but a high quality head phone solved that problem.? The frequency was off by 200 Hz, but a small change in the tuning?constant put it right on.? Say, did you receive the parts?? I was not sure of the address.
Frank Moskal
-----Original Message-----
From: "ns3l@... [SoftwareControlledHamRadio]"
Sent: Apr 24, 2016 3:57 AM
To: SoftwareControlledHamRadio@...
Subject: [SoftwareControlledHamRadio] Re: Low Audio, CP2 Proximity sensitivity
?
Right now I believe this is a bad component causing the problem. I have a signal generator that I was able to hear the tone clearly but very low, The DDS-VFO was only 10hz off in freq, I can fix that in the firmware setting, but the audio is so low I can't tell at this point how well the receiver is doing as far as sensitivity. I have known good antenna's so I'm not concerned with that. The low audio issue hopefully will be resolved soon..
One thing I have noted is that many of these kits are supplied by multiple companies on ebay, and you never know what quality the parts are going to be. It's hit or miss..
I would like to know what others have done as far as the two wire plastic modular antenna connector supplied with the kit.. How many have just simply soldered in RG174 right to the board out to a bnc chassis mount?
Other than that I can't find anything else that is causing the problem.. Possibly the replacement 386 chip will solve things.. At lease then I can chase the audio circuit and see if any other item is acting up.. Then I'll move on to setting up the transmitter side.. Small steps...?
Steve NS3L?
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Re: Low Audio, CP2 Proximity sensitivity
Steve, I just tried four different LM386 chips from a bunch I purchased from Tayda Electronics. Every one of them exhibited the same low audio qualities and excessive hiss coming from either headphones or my mini amplified speaker. One thing I do want to point out about using the speaker is that it simply takes what comes out of the headphone jack on the 49-er and boosts it... obviously. With no output to the speaker, it's very quiet. Basically, the speaker is simply amplifying the junk it hears from the 49-er and is not adding any noise on its own accord.
One thing I should point out is that 40m seems really dead this morning so it's probably not a good time for a signal test.
So with the same low audio and bad hiss coming from the 49-er using a different LM386, I'm thinking another component in the audio chain may be bad... or perhaps not a suitable value for the amplifier circuit. I've got several LM386 amplifier schematics I've downloaded from the internet. I'm going to put a few of them together - now that I have spare LM386 chips - and see if I get anything that sounds better than what's on the 49-er. Perhaps a mod is in order.
Aaron - N2HTL
?
Right now I believe this is a bad component causing the problem. I have a signal generator that I was able to hear the tone clearly but very low, The DDS-VFO was only 10hz off in freq, I can fix that in the firmware setting, but the audio is so low I can't tell at this point how well the receiver is doing as far as sensitivity. I have known good antenna's so I'm not concerned with that. The low audio issue hopefully will be resolved soon..
One thing I have noted is that many of these kits are supplied by multiple companies on ebay, and you never know what quality the parts are going to be. It's hit or miss..
I would like to know what others have done as far as the two wire plastic modular antenna connector supplied with the kit.. How many have just simply soldered in RG174 right to the board out to a bnc chassis mount?
Other than that I can't find anything else that is causing the problem.. Possibly the replacement 386 chip will solve things.. At lease then I can chase the audio circuit and see if any other item is acting up.. Then I'll move on to setting up the transmitter side.. Small steps...?
Steve NS3L?
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We had one member who thinks that his kit contained faulty/mis-labeled parts. If anyone else feels this way, please let me know the name of the supplier and I'll start a list of "questionable" suppliers and post it here.?
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Re: Low Audio, CP2 Proximity sensitivity
Right now I believe this is a bad component causing the problem. I have a signal generator that I was able to hear the tone clearly but very low, The DDS-VFO was only 10hz off in freq, I can fix that in the firmware setting, but the audio is so low I can't tell at this point how well the receiver is doing as far as sensitivity. I have known good antenna's so I'm not concerned with that. The low audio issue hopefully will be resolved soon..
One thing I have noted is that many of these kits are supplied by multiple companies on ebay, and you never know what quality the parts are going to be. It's hit or miss..
I would like to know what others have done as far as the two wire plastic modular antenna connector supplied with the kit.. How many have just simply soldered in RG174 right to the board out to a bnc chassis mount?
Other than that I can't find anything else that is causing the problem.. Possibly the replacement 386 chip will solve things.. At lease then I can chase the audio circuit and see if any other item is acting up.. Then I'll move on to setting up the transmitter side.. Small steps...?
Steve NS3L?
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Re: Low Audio, CP2 Proximity sensitivity
Hi Steve,
I experienced a similar low audio issue when I connected my radio for the first time. I could barely hear the stations and they sounded "far away". It all came down to the antenna. I found a bad connection on my dipole. Big difference after I fixed it, now I can hear stations pretty good. I was so focused on the radio that I totally overlooked the antenna.
73s
Norbert
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Re: Low Audio, CP2 Proximity sensitivity
I've had mine going for almost a year now and I've heard people all over the US and even a few in Europe, and that's with a crap antenna, so I know that the receiver can hear signals. My farthest contact is south GA, but I haven't tried that hard...too many other things to do! Still, it's a worthwhile rig and I think you'll find it fun to use once it's healthy.
Jack, W8TEE
From: "ns3l@... [SoftwareControlledHamRadio]"
To: SoftwareControlledHamRadio@...
Sent: Saturday, April 23, 2016 5:02 PM
Subject: Re: [SoftwareControlledHamRadio] Low Audio, CP2 Proximity sensitivity
?
Thanks Jack,
I pulled the LM386 and checked all the connections then reseated the chip.. As a backup I just ordered a couple and then I'll know if that is part of this. I don't know about the NE612 that came with it so I have a couple of them coming as well as backup.
I did follow all the previous messages regarding the correct number of windings done right as far as I know.. 11 on the black core, and 16 on the red core.. So I hope that's not contributing to the low receive audio..
I would think that if I can hear the signal tone from the SG that would go some distance to show the receiver is hearing.. Whether this is a audio amp failure I won't know for a few days until the chips get here. If the chip is bad and the audio comes back strong, then I'll be able to get a better sense of how it hears..?
I've only concentrated on the receive side and not done anything on the transmit side.. When that time comes, I have a Tek 2213 & 2210 along with a Tek 2710 SA to be able to get some readings to share.
I hope to be able to get this working soon..
Steve NS3L?
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Re: Low Audio, CP2 Proximity sensitivity
Hi Steve. There's nothing worse than someone replying to a cry for help on a forum with something like "I have the exact same problem... were you able to find a solution(?)". This is especially true if you're desperate for a resolution to a troubling problem and you get no responses other than that single one. Unfortunately, I have to chime in and say "I have the exact same problem." :-)
I did some research on the LM386 chip and found that while it's a pretty good amplifier, it's not without issues. I had mentioned this in another thread where the biggest problem is noise... but I've also found that it's susceptible to "motor-boating" and other forms of garbage because of the components hooked up to it and other inherent qualities of the chip itself. Mine, in fact, exhibits a slight "thumping" sound which seems to happen completely at random. While I didn't encounter any anomalies while getting close to CP2, I did find right off the bat that the audio coming from my 49-er was extremely low in several sets of headphones or earbuds. As I said earlier, I have my 49-er hooked up to an amplified mini-speaker from Radio Shack... and while this certainly brings up the level of signals coming from the radio, it also brings up the noise so that it sounds like a waterfall. I've received a dozen new LM386 chips that I can replace the original with, but I haven't had a minute to try a different one to see if that makes a difference. Stay tuned, I guess.
So my point to all of this is that you're not alone in the low audio level coming from your 49-er. But how is the signal to noise ratio? Do you hear an excessive amount of hiss?
Aaron - N2HTL
?
Thanks Jack,
I pulled the LM386 and checked all the connections then reseated the chip.. As a backup I just ordered a couple and then I'll know if that is part of this. I don't know about the NE612 that came with it so I have a couple of them coming as well as backup.
I did follow all the previous messages regarding the correct number of windings done right as far as I know.. 11 on the black core, and 16 on the red core.. So I hope that's not contributing to the low receive audio..
I would think that if I can hear the signal tone from the SG that would go some distance to show the receiver is hearing.. Whether this is a audio amp failure I won't know for a few days until the chips get here. If the chip is bad and the audio comes back strong, then I'll be able to get a better sense of how it hears..?
I've only concentrated on the receive side and not done anything on the transmit side.. When that time comes, I have a Tek 2213 & 2210 along with a Tek 2710 SA to be able to get some readings to share.
I hope to be able to get this working soon..
Steve NS3L?
|
Re: Low Audio, CP2 Proximity sensitivity
Thanks Jack,
I pulled the LM386 and checked all the connections then reseated the chip.. As a backup I just ordered a couple and then I'll know if that is part of this. I don't know about the NE612 that came with it so I have a couple of them coming as well as backup.
I did follow all the previous messages regarding the correct number of windings done right as far as I know.. 11 on the black core, and 16 on the red core.. So I hope that's not contributing to the low receive audio..
I would think that if I can hear the signal tone from the SG that would go some distance to show the receiver is hearing.. Whether this is a audio amp failure I won't know for a few days until the chips get here. If the chip is bad and the audio comes back strong, then I'll be able to get a better sense of how it hears..?
I've only concentrated on the receive side and not done anything on the transmit side.. When that time comes, I have a Tek 2213 & 2210 along with a Tek 2710 SA to be able to get some readings to share.
I hope to be able to get this working soon..
Steve NS3L?
|
jjpurdum