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s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
hi,
i'm noticing a discrepancy between the s-meter readings of these three radios. all three radios are connected to the same antenna for the test and signals can be heard equally well on all three, but the kenwood r-5000 always has the highest signal levels, by quite a bit - followed by the palstar and then the drake. the palstar and the drake are the closest. when i turn the pre-amp on the drake closes in on the palstar, but still a little low. are s-meter readings standardized - is this a fair way to test for a radios sensitivity. |
s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
In article .com,
"john" wrote: hi, i'm noticing a discrepancy between the s-meter readings of these three radios. all three radios are connected to the same antenna for the test and signals can be heard equally well on all three, but the kenwood r-5000 always has the highest signal levels, by quite a bit - followed by the palstar and then the drake. the palstar and the drake are the closest. when i turn the pre-amp on the drake closes in on the palstar, but still a little low. are s-meter readings standardized - is this a fair way to test for a radios sensitivity. Yes and no. Some radios have the same sensitivity and the relative S-meter reading, which is usually a reading of the AGC circuit would be of a similar value. Radios of dissimilar sensitivity would not normally have the same readings. An exception would be radios that have a signal strength meter in dBm, which is an absolute scale. -- Telamon Ventura, California |
s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
On Fri, 05 Jan 2007 02:17:32 GMT, Telamon
wrote: In article .com, "john" wrote: An exception would be radios that have a signal strength meter in dBm, which is an absolute scale. Millivolts? |
s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
David wrote: On Fri, 05 Jan 2007 02:17:32 GMT, Telamon wrote: In article .com, "john" wrote: An exception would be radios that have a signal strength meter in dBm, which is an absolute scale. Millivolts? actually the palstar and the drake scales are in Decibels, while the kenwoods scale is in Db at the top and millivolts at the bottom. also before anyone asks my rf gain is fully clockwise on both the drake and kenwood. the palstar doesn't have a rf gain control. |
s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
In article m,
"john" wrote: David wrote: On Fri, 05 Jan 2007 02:17:32 GMT, Telamon wrote: In article .com, "john" wrote: An exception would be radios that have a signal strength meter in dBm, which is an absolute scale. Millivolts? actually the palstar and the drake scales are in Decibels, while the kenwoods scale is in Db at the top and millivolts at the bottom. also before anyone asks my rf gain is fully clockwise on both the drake and kenwood. the palstar doesn't have a rf gain control. No. decibels where 0 dBm = 0.001 Watt or 1 milliwatt. However in a 50 ohm system the equivalent would be 225 millivolts. -- Telamon Ventura, California |
s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
In article m,
"john" wrote: David wrote: On Fri, 05 Jan 2007 02:17:32 GMT, Telamon wrote: In article .com, "john" wrote: An exception would be radios that have a signal strength meter in dBm, which is an absolute scale. Millivolts? actually the palstar and the drake scales are in Decibels, while the kenwoods scale is in Db at the top and millivolts at the bottom. also before anyone asks my rf gain is fully clockwise on both the drake and kenwood. the palstar doesn't have a rf gain control. The RF gain control just sets maximum sensitivity of the radio and does not change the gain of the radio so by turning all the way down you are at the radios published maximum sensitivity. As you turn it up you are desensitizing the radio. If you turn the control so it rests at S3 then you would only be able to hear signals greater then S3. The AGC would work on signals higher then than S3. The radio will behave exactly the same for any signal greater than S3. -- Telamon Ventura, California |
s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
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s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
In article ,
BDK wrote: In article m, says... David wrote: On Fri, 05 Jan 2007 02:17:32 GMT, Telamon wrote: In article .com, "john" wrote: An exception would be radios that have a signal strength meter in dBm, which is an absolute scale. Millivolts? actually the palstar and the drake scales are in Decibels, while the kenwoods scale is in Db at the top and millivolts at the bottom. also before anyone asks my rf gain is fully clockwise on both the drake and kenwood. the palstar doesn't have a rf gain control. You can't even be sure identical radios will have the same S-Meter readings, in most cases. The reading is pretty meaningless, except to compare antennas, or if a preselector is used, to adjust for max reading. Nonsense. -- Telamon Ventura, California |
s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
Telamon wrote: In article , BDK wrote: In article m, says... David wrote: On Fri, 05 Jan 2007 02:17:32 GMT, Telamon wrote: In article .com, "john" wrote: An exception would be radios that have a signal strength meter in dBm, which is an absolute scale. Millivolts? actually the palstar and the drake scales are in Decibels, while the kenwoods scale is in Db at the top and millivolts at the bottom. also before anyone asks my rf gain is fully clockwise on both the drake and kenwood. the palstar doesn't have a rf gain control. You can't even be sure identical radios will have the same S-Meter readings, in most cases. The reading is pretty meaningless, except to compare antennas, or if a preselector is used, to adjust for max reading. Nonsense. -- Telamon Ventura, California so a stronger s-meter reading on one radio indicates the more sensitive radio? in this case the kenwood? |
s-meter readings - drake r8 vs.palstar r30cc vs. kenwoodr-5000.
Sort of like fuel gages/sending units in cars,they can be off by quite a
bit. cuhulin |
s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
In article .com,
"john" wrote: Telamon wrote: In article , BDK wrote: In article m, says... David wrote: On Fri, 05 Jan 2007 02:17:32 GMT, Telamon wrote: In article .com, "john" wrote: An exception would be radios that have a signal strength meter in dBm, which is an absolute scale. Millivolts? actually the palstar and the drake scales are in Decibels, while the kenwoods scale is in Db at the top and millivolts at the bottom. also before anyone asks my rf gain is fully clockwise on both the drake and kenwood. the palstar doesn't have a rf gain control. You can't even be sure identical radios will have the same S-Meter readings, in most cases. The reading is pretty meaningless, except to compare antennas, or if a preselector is used, to adjust for max reading. Nonsense. -- Telamon Ventura, California so a stronger s-meter reading on one radio indicates the more sensitive radio? in this case the kenwood? It could. Like I posted earlier the readings would be comparable if the radio has an absolute scale such as dBm instead of a relative scale. -- Telamon Ventura, California |
s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
How do you figure that this is nonsense? Typically, SWL radios would have
their S-Meter calibrated at 14MHz, so that S9 would equal 50uV. You are correct when you mention S-Meters that are calibrated in dBm as being absolute, as long as the system in in calibration for gain distribution, etc. Receivers that have this function do provide for setting up the gain distribution. Now, the mystery continues.................what exactly do you mean by the following statement? "The RF gain control just sets maximum sensitivity of the radio and does not change the gain of the radio so by turning all the way down you are at the radios published maximum sensitivity. As you turn it up you are desensitizing the radio." The above statement, in quotes, is a new one to me. Could be showing my young 54 year old age. The RF gain control only sets the maximum sensitivity of the radio when it is controlling the bias to the RF stage in addition to the I.F. stages, and this usually isn't the case, except for some of the older tubed equipment. Most RF gain controls USUALLY only set the gain of the I.F. stage. This has nothing to do with the sensitivity of the system, if we are talking about noise figure (I realize that you didn't mention that, so I won't put words in you mouth on this one). When you turn up the RF gain control, you don't desense the radio, but you do give the AGC loop more gain. Maybe this is what you meant. Pete |
s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
No.
"john" wrote in message oups.com... Telamon wrote: In article , BDK wrote: In article m, says... David wrote: On Fri, 05 Jan 2007 02:17:32 GMT, Telamon wrote: In article s.com, "john" wrote: An exception would be radios that have a signal strength meter in dBm, which is an absolute scale. Millivolts? actually the palstar and the drake scales are in Decibels, while the kenwoods scale is in Db at the top and millivolts at the bottom. also before anyone asks my rf gain is fully clockwise on both the drake and kenwood. the palstar doesn't have a rf gain control. You can't even be sure identical radios will have the same S-Meter readings, in most cases. The reading is pretty meaningless, except to compare antennas, or if a preselector is used, to adjust for max reading. Nonsense. -- Telamon Ventura, California so a stronger s-meter reading on one radio indicates the more sensitive radio? in this case the kenwood? |
s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
"Telamon" wrote in message ... In article .com, "john" wrote: Telamon wrote: In article , BDK wrote: In article m, says... David wrote: On Fri, 05 Jan 2007 02:17:32 GMT, Telamon wrote: In article s.com, "john" wrote: An exception would be radios that have a signal strength meter in dBm, which is an absolute scale. Millivolts? actually the palstar and the drake scales are in Decibels, while the kenwoods scale is in Db at the top and millivolts at the bottom. also before anyone asks my rf gain is fully clockwise on both the drake and kenwood. the palstar doesn't have a rf gain control. You can't even be sure identical radios will have the same S-Meter readings, in most cases. The reading is pretty meaningless, except to compare antennas, or if a preselector is used, to adjust for max reading. Nonsense. -- Telamon Ventura, California so a stronger s-meter reading on one radio indicates the more sensitive radio? in this case the kenwood? It could. Like I posted earlier the readings would be comparable if the radio has an absolute scale such as dBm instead of a relative scale. -- Telamon Ventura, California If the radio has a meter that is calibrated in dBm, it should have identical readings with another radio that has a meter calibrated in this manner. But.....................it is possible that one of the radios can hear weak signals better. Most of the radios that have an S-Meter calibrated in dBm are millitary radios that are built to a certain spec. True, there may be some differences in perceived signal quality, but generally, you can take a Rockwell HF-2050, HF-8000 series, a Harris RF-590, Racal 6790, a WJ 8718, and they will all sound very similar. The design spec is going to call for a certain amount of gain, overload rejection etc. If the receiver doesn't meet these specs, the manufacturer can lose the contract. Pete |
s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
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RADIOS : "Relative" S-Meter Readings -vice- What-Your-Ears-Tell-You !
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s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
In article .com,
says... Telamon wrote: In article , BDK wrote: In article m, says... David wrote: On Fri, 05 Jan 2007 02:17:32 GMT, Telamon wrote: In article .com, "john" wrote: An exception would be radios that have a signal strength meter in dBm, which is an absolute scale. Millivolts? actually the palstar and the drake scales are in Decibels, while the kenwoods scale is in Db at the top and millivolts at the bottom. also before anyone asks my rf gain is fully clockwise on both the drake and kenwood. the palstar doesn't have a rf gain control. You can't even be sure identical radios will have the same S-Meter readings, in most cases. The reading is pretty meaningless, except to compare antennas, or if a preselector is used, to adjust for max reading. Nonsense. -- Telamon Ventura, California so a stronger s-meter reading on one radio indicates the more sensitive radio? in this case the kenwood? Now THAT would be nonsense. Even supposedly identical receivers have differing S-Meter readings. You can set the meter level to whatever you want. They supposedly are normally calibrated to something like S-9 = 50 Microvolts. Supposedly. But like any other adjustment, it can be off. BDK |
s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
In article telamon_spamshield-2557A0.23063004012007
@newsclstr03.news.prodigy.net, lid says... In article .com, "john" wrote: Telamon wrote: In article , BDK wrote: In article m, says... David wrote: On Fri, 05 Jan 2007 02:17:32 GMT, Telamon wrote: In article .com, "john" wrote: An exception would be radios that have a signal strength meter in dBm, which is an absolute scale. Millivolts? actually the palstar and the drake scales are in Decibels, while the kenwoods scale is in Db at the top and millivolts at the bottom. also before anyone asks my rf gain is fully clockwise on both the drake and kenwood. the palstar doesn't have a rf gain control. You can't even be sure identical radios will have the same S-Meter readings, in most cases. The reading is pretty meaningless, except to compare antennas, or if a preselector is used, to adjust for max reading. Nonsense. -- Telamon Ventura, California so a stronger s-meter reading on one radio indicates the more sensitive radio? in this case the kenwood? It could. Like I posted earlier the readings would be comparable if the radio has an absolute scale such as dBm instead of a relative scale. And most SW and ham radios don't. BDK |
s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
In article telamon_spamshield-F6523C.20501704012007
@newsclstr02.news.prodigy.com, lid says... In article , BDK wrote: In article m, says... David wrote: On Fri, 05 Jan 2007 02:17:32 GMT, Telamon wrote: In article .com, "john" wrote: An exception would be radios that have a signal strength meter in dBm, which is an absolute scale. Millivolts? actually the palstar and the drake scales are in Decibels, while the kenwoods scale is in Db at the top and millivolts at the bottom. also before anyone asks my rf gain is fully clockwise on both the drake and kenwood. the palstar doesn't have a rf gain control. You can't even be sure identical radios will have the same S-Meter readings, in most cases. The reading is pretty meaningless, except to compare antennas, or if a preselector is used, to adjust for max reading. Nonsense. Wanna bet? In most cases, side by side, identical models have different meter readings. Usually it's slight, but sometimes it's huge. My JRC NRD-515 has a "tight" meter. SSB audio can be clearly heard with the meter at the left peg. Another 515 I had here for interconnect repair was just as sensitive as mine, but the same signal would read S-2 or 3. Same thing has happened with Kenwood R5000's, R2000's, and JRC NRD-525s. (The first ones had a "spastic" S-Meter, later ones were cured of this) In "pro" radios it might be true, but in hobby receivers, it's not true that S-meters have any real correlation with signal strength in comparing one radio to another. BDK |
s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
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RADIOS : "Relative" S-Meter Readings -vice- What-Your-Ears-Tell-You !
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s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
In article ,
"Pete KE9OA" wrote: How do you figure that this is nonsense? Well let's quote the the statement that I responded to OK? In article , BDK wrote: You can't even be sure identical radios will have the same S-Meter readings, in most cases. The reading is pretty meaningless, except to compare antennas, or if a preselector is used, to adjust for max reading. You already answered one exception to this blanket statement about radios calibrated in an absolute scale. Here is another exception, you can be reasonably sure that the same model radio will have similar readings. Typically, SWL radios would have their S-Meter calibrated at 14MHz, so that S9 would equal 50uV. You are correct when you mention S-Meters that are calibrated in dBm as being absolute, as long as the system in in calibration for gain distribution, etc. Receivers that have this function do provide for setting up the gain distribution. Now, the mystery continues.................what exactly do you mean by the following statement? "The RF gain control just sets maximum sensitivity of the radio and does not change the gain of the radio so by turning all the way down you are at the radios published maximum sensitivity. As you turn it up you are desensitizing the radio." The above statement, in quotes, is a new one to me. Could be showing my young 54 year old age. The RF gain control only sets the maximum sensitivity of the radio when it is controlling the bias to the RF stage in addition to the I.F. stages, and this usually isn't the case, except for some of the older tubed equipment. Most RF gain controls USUALLY only set the gain of the I.F. stage. This has nothing to do with the sensitivity of the system, if we are talking about noise figure (I realize that you didn't mention that, so I won't put words in you mouth on this one). When you turn up the RF gain control, you don't desense the radio, but you do give the AGC loop more gain. Maybe this is what you meant. Man, you are ancient. No I pretty much meant what the user would experience using the radio. Looking at the radio as a black box and not understanding how all the circuits inside actually operate I described what would happen as the RF gain control is operated with the AGC circuit on. The perspective here is what to expect from the operation of the RF gain control not unlike what to expect from the S-meter, which is the subject of the thread. -- Telamon Ventura, California |
s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
In article ,
"Pete KE9OA" wrote: "john" wrote in message oups.com... Telamon wrote: In article , BDK wrote: In article m, says... David wrote: On Fri, 05 Jan 2007 02:17:32 GMT, Telamon wrote: In article s.com, "john" wrote: An exception would be radios that have a signal strength meter in dBm, which is an absolute scale. Millivolts? actually the palstar and the drake scales are in Decibels, while the kenwoods scale is in Db at the top and millivolts at the bottom. also before anyone asks my rf gain is fully clockwise on both the drake and kenwood. the palstar doesn't have a rf gain control. You can't even be sure identical radios will have the same S-Meter readings, in most cases. The reading is pretty meaningless, except to compare antennas, or if a preselector is used, to adjust for max reading. Nonsense. so a stronger s-meter reading on one radio indicates the more sensitive radio? in this case the kenwood? No. I would go with a big maybe. -- Telamon Ventura, California |
s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
In article ,
BDK wrote: In article telamon_spamshield-2557A0.23063004012007 @newsclstr03.news.prodigy.net, lid says... In article .com, "john" wrote: Telamon wrote: In article , BDK wrote: In article m, says... David wrote: On Fri, 05 Jan 2007 02:17:32 GMT, Telamon wrote: In article s.com, "john" wrote: An exception would be radios that have a signal strength meter in dBm, which is an absolute scale. Millivolts? actually the palstar and the drake scales are in Decibels, while the kenwoods scale is in Db at the top and millivolts at the bottom. also before anyone asks my rf gain is fully clockwise on both the drake and kenwood. the palstar doesn't have a rf gain control. You can't even be sure identical radios will have the same S-Meter readings, in most cases. The reading is pretty meaningless, except to compare antennas, or if a preselector is used, to adjust for max reading. Nonsense. -- Telamon Ventura, California so a stronger s-meter reading on one radio indicates the more sensitive radio? in this case the kenwood? It could. Like I posted earlier the readings would be comparable if the radio has an absolute scale such as dBm instead of a relative scale. And most SW and ham radios don't. That's true... -- Telamon Ventura, California |
s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
In article ,
David wrote: On Fri, 5 Jan 2007 10:51:03 +0000 (UTC), (Geoffrey S. Mendelson) wrote: Pete KE9OA wrote: When you turn up the RF gain control, you don't desense the radio, but you do give the AGC loop more gain. Maybe this is what you meant. Wouldn't that make it an IF GAIN control? A while back I read a review by the ARRL of a transciver and they brought up an interesting point. Modern receivers have enough gain to "hear" the normal background noise, so beyond that it really does not matter. In my environment the noise is so high that almost anything can hear it, my R-5000 often hears S9 level background noise on 40m and nearby SW bands. (5-10mHz). Geoff. The RF gain control can be very handy for reducing noise to the point where SSB voice comms sound extremely HiFi. Putting the AGC on slow also helps for a similar reason. -- Telamon Ventura, California |
s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
In article telamon_spamshield-C9BF19.20290005012007
@newsclstr03.news.prodigy.net, lid says... In article , BDK wrote: In article telamon_spamshield-F6523C.20501704012007 @newsclstr02.news.prodigy.com, lid says... In article , BDK wrote: In article m, says... David wrote: On Fri, 05 Jan 2007 02:17:32 GMT, Telamon wrote: In article .com, "john" wrote: An exception would be radios that have a signal strength meter in dBm, which is an absolute scale. Millivolts? actually the palstar and the drake scales are in Decibels, while the kenwoods scale is in Db at the top and millivolts at the bottom. also before anyone asks my rf gain is fully clockwise on both the drake and kenwood. the palstar doesn't have a rf gain control. You can't even be sure identical radios will have the same S-Meter readings, in most cases. The reading is pretty meaningless, except to compare antennas, or if a preselector is used, to adjust for max reading. Nonsense. Wanna bet? In most cases, side by side, identical models have different meter readings. Usually it's slight, but sometimes it's huge. My JRC NRD-515 has a "tight" meter. SSB audio can be clearly heard with the meter at the left peg. Another 515 I had here for interconnect repair was just as sensitive as mine, but the same signal would read S-2 or 3. Same thing has happened with Kenwood R5000's, R2000's, and JRC NRD-525s. (The first ones had a "spastic" S-Meter, later ones were cured of this) In "pro" radios it might be true, but in hobby receivers, it's not true that S-meters have any real correlation with signal strength in comparing one radio to another. Oh come on. The same model with the same factory adjustment would have the same reading or very close. It would be reasonable to see a small variation but a "huge" difference would indicate a problem with one of the radios. Obviously, your and my idea of "tolerances" isn't what theirs is. A whole lot of radios are aligned "just good enough", or they need touching up due to aging after a really short time. Some just are not right at all out of the box, and a slight adjustment works wonders. I've seen huge differences between Icom R-71A's. Some, like the last one I had were dead on freq, the PBT was aligned right, etc, but some I had previously owned, and worked on weren't even close. Some of these were brand new, and I was helping the owner install a filter or something. when compared to a good one, it was obvious something was wrong. Electronic Equipment Bank (EEB) sold a lot of alignments on brand new radios, as the factories weren't doing a real good job of it. They would turn on your brand new R71A, R5000, Yaesu FRG-8800, and let it cook for a couple days, then align it. Then there is the thing all the major brands of ham and SW equipment have in common, the lack of ability to tighten screws. Most were just snugged, and by the time the thing had ridden across the country in a UPS or Fedex truck, gone through a few heat/cool cycles in the process, they weren't even close to being tight anymore. Even after an EEB alignment, the S-Meter's could still be off a little from one to the next. Then you have techs who forget to tighten screws in your $1000 receiver before they ship it, and not only does the alignment get messed up, but you are overjoyed that something wasn't broken. Yes, it happened to me about 15 years ago. I sent my NRD-515 in for a minor problem, more an annoyance than anything else. When it came back, it rattled, and two screws holding the top PC board had fallen out, and the rest were so loose they were about to fall out. I ended up checking around and finding a good freq counter and realigned it myself. Close, but not 100% right, I need to do it again. I also fixed the original problem that they "couldn't duplicate". Odd, since it did it as soon as I turned it on after I put the screws back in and tightened it all up. The only real way to compare (without any equipment) two radios is to hook them up to a coax switch and then to the same antenna, and switch them back and forth to compare. BDK |
s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
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s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
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s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
BDK ) writes:
In "pro" radios it might be true, but in hobby receivers, it's not true that S-meters have any real correlation with signal strength in comparing one radio to another. Oh come on. The same model with the same factory adjustment would have the same reading or very close. It would be reasonable to see a small variation but a "huge" difference would indicate a problem with one of the radios. Obviously, your and my idea of "tolerances" isn't what theirs is. A whole lot of radios are aligned "just good enough", or they need touching up due to aging after a really short time. But fundamental to all this talk about s-meters is that they never were intended to be anything but a relative indicator. And once you have that situation, there is little reason for the manufacturers to fuss over them. They are great to indicate at a glance that one station is stronger than the other, and if you need to peak or null something they provide a better indicator than your ears, and as I once saw suggested, they are a great way to get a rough idea of whether your receiver is working fine or not (just turn on the crystal calibrator when you first get the receiver, and then record the s-meter readings on various bands. If those start changing dramatically, then something is wrong, though it's no indication of what might be weakening.). Over the years, there's been lots of discussion of "how much is an s-unit" and while some have tried to impose a value on it, there really isn't anything to it. Before there were actual meters attached to receivers, there were the magic eye tubes, which had no scale at all. "You're about half open on the magic eye tube..." Want to give someone a better s-reading? Put up a bigger antenna, or add a preamp ahead of the receiver. It will raise the meter reading, but the signal as it arrives at your antenna hasn't changed one bit. Before there were meters on receivers, there was the "RST" system for rating signals. Readability/Signal Strength/Tone that you'd transmit to the other guy to give an indication of how his signal sounded at your receiver. It was all subjective, but nevertheless likely helpful to some extent in the early days of radio. Even today, some amateur radio contests require the exchange of RST, though it's my impression that in those cases they just send "59" or "599" (for code, the "T" relates to the tone of the signal and doesn't apply to voice) to comply with the rules and don't bother to actually send something that reflects the state of the signal at their receiver. From the 1961 ARRL Handbook, this is the how you are supposed to interpret the Signal Strength code: 1 faint signal, barely perceptible 2 very weak signal 3 weak signal 4 fair signal 5 fairly good signal 6 good signal 7 moderately strong signal 8 strong signal 9 extremely strong signal I can no longer remember if I read it outright years ago, or made an assumption, but somewhere I got the impression that S-meters are named after the RST system. Given that, any attempt at defining an s-unit is retroactive, trying to impose some absolute on something that has always been relative. One of the silliest things I ever saw was a digital s-meter to attach to CB sets. It was a 2-digit digital voltmeter, and you'd attach it to the AGC line of your CB set (all s-meters are just voltmeters measuring the voltage on the AGC line), and get flashy numbers. I can't recall if it did anything to actual give the basic idea of s-units, or just was a linear voltmeter. I'm sure it did sell well, because it was the sort of gadgetry that would sell at the time, and the whole concept of s-meters is so muddled that I'm sure the less technically inclined would buy into the notion of digital s-meters. Michael |
s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
Yes, that would make it an I.F. gain control, and that is what it is most of
the time. I don't know why manufacturers still use the misnomer "RF Gain" for this control. Concerning the ARRL, when they talk about having only enough gain to hear the normal background noise they are usually talking about RF amplification ahead of the 1st mixer. It is important to pay careful attention to the gain distribution of the receiver, since any gain ahead of the 1st mixer degrades the dynamic range by that same amount. As an example, suppose a receiver has an IP3 of +30dBm. Now, if a preamplifier with 10dB of gain is placed ahead of the 1st mixer the IP3 will be degraded to +20dBm. Typically, excess noise contributed by the environment is in the 15 to 20dB range. Many shortwave receivers have a noise figure in the 10 to 12dB range. The excess environmental noise can be between 3 to 5dB above any noise contribution that the receiver has itself. For this reason, most modern receivers don't use an RF amplifier ahead of the 1st mixer. Some receivers, such as the AOR-7030 have a post-mixer amplifier. Any amplification after the 1st mixer won't degrade out of band IMD performance unless signals fall within the range of the roofing filter that follows the 1st mixer. Now, another point comes into consideration..............close-in IP3 performance. Three major mechanisms affect this parameter. First of all, the performance of the 2nd mixer itself. Most receivers use a "weaker" 2nd mixer since the roofing filter protects this device from out of band signals. If a stronger 2nd mixer with better IMD performance is used, the close-in IMD will improve. The 2nd parameter is the sideband noise of the synthesizer itself. If phase noise can be improved, close-in IMD performance will improve. Of course, the parameters of the roofing filter itself will directly affect the close-in IMD performance. As an example, both the Racal 6790 and the JRC NRD-515 are using at least an 8-pole crystal filter as the roofing filter at the 1st I.F. The 6790 has some amplification that follows the roofing filter, and another roofing filter is added after that amplification. The result is exceptional skirt selectivity at the 1st I.F. This affords quite a bit of out of band protection for the 2nd mixer. Another example is the Collins 651S-1. This is a triple conversion receiver. At the 1st I.F. of 110.35MHz, an 8-pole crystal filter is used. At the 2nd I.F. of 10.35MHz?, another 8-pole crystal filter is used. At the 3rd I.F. of either 450 or 455kHz, depending on when the receiver was manufactured, mechanical filters are used. These things are what set the "premium grade" receivers apart from most of the consumer equipment. Do we really need this kind of front end protection? Probably not, unless the receiver is going to be used on an ocean going vessel that has multi-kilowatt transmitters. Even in this scene, narrow band RF preselectors are used ahead of the receivers to add additional IMD protection. I hope this helps. Pete "Geoffrey S. Mendelson" wrote in message ... Pete KE9OA wrote: When you turn up the RF gain control, you don't desense the radio, but you do give the AGC loop more gain. Maybe this is what you meant. Wouldn't that make it an IF GAIN control? A while back I read a review by the ARRL of a transciver and they brought up an interesting point. Modern receivers have enough gain to "hear" the normal background noise, so beyond that it really does not matter. In my environment the noise is so high that almost anything can hear it, my R-5000 often hears S9 level background noise on 40m and nearby SW bands. (5-10mHz). Geoff. -- Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM IL Voice: (07)-7424-1667 Fax ONLY: 972-2-648-1443 U.S. Voice: 1-215-821-1838 Visit my 'blog at http://geoffstechno.livejournal.com/ |
s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
That does add a bit of "nicety" to the recovered audio.
Pete "Telamon" wrote in message ... In article , David wrote: On Fri, 5 Jan 2007 10:51:03 +0000 (UTC), (Geoffrey S. Mendelson) wrote: Pete KE9OA wrote: When you turn up the RF gain control, you don't desense the radio, but you do give the AGC loop more gain. Maybe this is what you meant. Wouldn't that make it an IF GAIN control? A while back I read a review by the ARRL of a transciver and they brought up an interesting point. Modern receivers have enough gain to "hear" the normal background noise, so beyond that it really does not matter. In my environment the noise is so high that almost anything can hear it, my R-5000 often hears S9 level background noise on 40m and nearby SW bands. (5-10mHz). Geoff. The RF gain control can be very handy for reducing noise to the point where SSB voice comms sound extremely HiFi. Putting the AGC on slow also helps for a similar reason. -- Telamon Ventura, California |
s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
"Telamon" wrote in message ... In article , "Pete KE9OA" wrote: How do you figure that this is nonsense? Well let's quote the the statement that I responded to OK? In article , BDK wrote: You can't even be sure identical radios will have the same S-Meter readings, in most cases. The reading is pretty meaningless, except to compare antennas, or if a preselector is used, to adjust for max reading. You already answered one exception to this blanket statement about radios calibrated in an absolute scale. Here is another exception, you can be reasonably sure that the same model radio will have similar readings. Typically, SWL radios would have their S-Meter calibrated at 14MHz, so that S9 would equal 50uV. You are correct when you mention S-Meters that are calibrated in dBm as being absolute, as long as the system in in calibration for gain distribution, etc. Receivers that have this function do provide for setting up the gain distribution. Now, the mystery continues.................what exactly do you mean by the following statement? "The RF gain control just sets maximum sensitivity of the radio and does not change the gain of the radio so by turning all the way down you are at the radios published maximum sensitivity. As you turn it up you are desensitizing the radio." The above statement, in quotes, is a new one to me. Could be showing my young 54 year old age. The RF gain control only sets the maximum sensitivity of the radio when it is controlling the bias to the RF stage in addition to the I.F. stages, and this usually isn't the case, except for some of the older tubed equipment. Most RF gain controls USUALLY only set the gain of the I.F. stage. This has nothing to do with the sensitivity of the system, if we are talking about noise figure (I realize that you didn't mention that, so I won't put words in you mouth on this one). When you turn up the RF gain control, you don't desense the radio, but you do give the AGC loop more gain. Maybe this is what you meant. Man, you are ancient. How did you know? Have you looked at the service manuals of the more recent equipment? I don't think so. No I pretty much meant what the user would experience using the radio. Looking at the radio as a black box and not understanding how all the circuits inside actually operate I described what would happen as the RF gain control is operated with the AGC circuit on. The perspective here is what to expect from the operation of the RF gain control not unlike what to expect from the S-meter, which is the subject of the thread. -- Telamon Ventura, California That still doesn't make sense. As you advance the setting on the RF gain control, the S-Meter reading will increase, unless you are talking about some of the older tubed units that used a negative AGC and had the S-Meter at full-scale when the receiver was powered down. Now, about being ancient........................................... .... Pete |
RADIOS : "Relative" S-Meter Readings -vice- What-Your-Ears-Tell-You !
It's been a great discussion. Great group!
Pete "BDK" wrote in message ... In article , says... S-UNIT DISCUSSIONS AT URL: http://www.ac6v.com/sunit.htm CL Good page. BDK |
s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
In article ,
"Pete KE9OA" wrote: "Telamon" wrote in message ... In article , "Pete KE9OA" wrote: How do you figure that this is nonsense? Well let's quote the the statement that I responded to OK? In article , BDK wrote: You can't even be sure identical radios will have the same S-Meter readings, in most cases. The reading is pretty meaningless, except to compare antennas, or if a preselector is used, to adjust for max reading. You already answered one exception to this blanket statement about radios calibrated in an absolute scale. Here is another exception, you can be reasonably sure that the same model radio will have similar readings. Typically, SWL radios would have their S-Meter calibrated at 14MHz, so that S9 would equal 50uV. You are correct when you mention S-Meters that are calibrated in dBm as being absolute, as long as the system in in calibration for gain distribution, etc. Receivers that have this function do provide for setting up the gain distribution. Now, the mystery continues.................what exactly do you mean by the following statement? "The RF gain control just sets maximum sensitivity of the radio and does not change the gain of the radio so by turning all the way down you are at the radios published maximum sensitivity. As you turn it up you are desensitizing the radio." The above statement, in quotes, is a new one to me. Could be showing my young 54 year old age. The RF gain control only sets the maximum sensitivity of the radio when it is controlling the bias to the RF stage in addition to the I.F. stages, and this usually isn't the case, except for some of the older tubed equipment. Most RF gain controls USUALLY only set the gain of the I.F. stage. This has nothing to do with the sensitivity of the system, if we are talking about noise figure (I realize that you didn't mention that, so I won't put words in you mouth on this one). When you turn up the RF gain control, you don't desense the radio, but you do give the AGC loop more gain. Maybe this is what you meant. Man, you are ancient. How did you know? Have you looked at the service manuals of the more recent equipment? I don't think so. None of the manuals I read had anything about your age in them. No I pretty much meant what the user would experience using the radio. Looking at the radio as a black box and not understanding how all the circuits inside actually operate I described what would happen as the RF gain control is operated with the AGC circuit on. The perspective here is what to expect from the operation of the RF gain control not unlike what to expect from the S-meter, which is the subject of the thread. -- Telamon Ventura, California That still doesn't make sense. As you advance the setting on the RF gain control, the S-Meter reading will increase, unless you are talking about some of the older tubed units that used a negative AGC and had the S-Meter at full-scale when the receiver was powered down. Now, about being ancient........................................... .... Well, I don't think I can help you then. -- Telamon Ventura, California |
s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
In article ,
"Pete KE9OA" wrote: Yes, that would make it an I.F. gain control, and that is what it is most of the time. I don't know why manufacturers still use the misnomer "RF Gain" for this control. Snip If the signal has not gone through a demodulation stage it it still a modulated carrier so even if it is a mixed IF product it is all a part of the RF gain stage in the radio. I agree with you that it would be better to call it a IF gain control. -- Telamon Ventura, California |
s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
In article ,
"Pete KE9OA" wrote: Snip As an example, suppose a receiver has an IP3 of +30dBm. Now, if a preamplifier with 10dB of gain is placed ahead of the 1st mixer the IP3 will be degraded to +20dBm. Typically, excess noise contributed by the environment is in the 15 to 20dB range. Many shortwave receivers have a noise figure in the 10 to 12dB range. The excess environmental noise can be between 3 to 5dB above any noise contribution that the receiver has itself. For this reason, most modern receivers don't use an RF amplifier ahead of the 1st mixer. Snip Most of the better modern receivers have a switchable RF amplifier because the background noise is higher at lower frequencies and as you noted can reduce the intermodulation performance so with adjustable or switchable RF gain you can use it at higher frequencies or actually at any frequency as conditions permit. -- Telamon Ventura, California |
s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
In article ,
"Pete KE9OA" wrote: Snip Now, another point comes into consideration..............close-in IP3 performance. Three major mechanisms affect this parameter. First of all, the performance of the 2nd mixer itself. Most receivers use a "weaker" 2nd mixer since the roofing filter protects this device from out of band signals. If a stronger 2nd mixer with better IMD performance is used, the close-in IMD will improve. Snip Every stage in the radio that the signal has to pass through will add its own set of intermodulation products. RF amplifiers, RF attenuators, all and any mixers, IF amplifiers, filters, and demodulators. -- Telamon Ventura, California |
s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
In article ,
BDK wrote: In article telamon_spamshield-C9BF19.20290005012007 @newsclstr03.news.prodigy.net, lid says... In article , BDK wrote: In article telamon_spamshield-F6523C.20501704012007 @newsclstr02.news.prodigy.com, lid says... In article , BDK wrote: In article m, says... David wrote: On Fri, 05 Jan 2007 02:17:32 GMT, Telamon wrote: In article s.com, "john" wrote: An exception would be radios that have a signal strength meter in dBm, which is an absolute scale. Millivolts? actually the palstar and the drake scales are in Decibels, while the kenwoods scale is in Db at the top and millivolts at the bottom. also before anyone asks my rf gain is fully clockwise on both the drake and kenwood. the palstar doesn't have a rf gain control. You can't even be sure identical radios will have the same S-Meter readings, in most cases. The reading is pretty meaningless, except to compare antennas, or if a preselector is used, to adjust for max reading. Nonsense. Wanna bet? In most cases, side by side, identical models have different meter readings. Usually it's slight, but sometimes it's huge. My JRC NRD-515 has a "tight" meter. SSB audio can be clearly heard with the meter at the left peg. Another 515 I had here for interconnect repair was just as sensitive as mine, but the same signal would read S-2 or 3. Same thing has happened with Kenwood R5000's, R2000's, and JRC NRD-525s. (The first ones had a "spastic" S-Meter, later ones were cured of this) In "pro" radios it might be true, but in hobby receivers, it's not true that S-meters have any real correlation with signal strength in comparing one radio to another. Oh come on. The same model with the same factory adjustment would have the same reading or very close. It would be reasonable to see a small variation but a "huge" difference would indicate a problem with one of the radios. Obviously, your and my idea of "tolerances" isn't what theirs is. A whole lot of radios are aligned "just good enough", or they need touching up due to aging after a really short time. Some just are not right at all out of the box, and a slight adjustment works wonders. I've seen huge differences between Icom R-71A's. Some, like the last one I had were dead on freq, the PBT was aligned right, etc, but some I had previously owned, and worked on weren't even close. Some of these were brand new, and I was helping the owner install a filter or something. when compared to a good one, it was obvious something was wrong. Electronic Equipment Bank (EEB) sold a lot of alignments on brand new radios, as the factories weren't doing a real good job of it. They would turn on your brand new R71A, R5000, Yaesu FRG-8800, and let it cook for a couple days, then align it. Then there is the thing all the major brands of ham and SW equipment have in common, the lack of ability to tighten screws. Most were just snugged, and by the time the thing had ridden across the country in a UPS or Fedex truck, gone through a few heat/cool cycles in the process, they weren't even close to being tight anymore. Even after an EEB alignment, the S-Meter's could still be off a little from one to the next. Then you have techs who forget to tighten screws in your $1000 receiver before they ship it, and not only does the alignment get messed up, but you are overjoyed that something wasn't broken. Yes, it happened to me about 15 years ago. I sent my NRD-515 in for a minor problem, more an annoyance than anything else. When it came back, it rattled, and two screws holding the top PC board had fallen out, and the rest were so loose they were about to fall out. I ended up checking around and finding a good freq counter and realigned it myself. Close, but not 100% right, I need to do it again. I also fixed the original problem that they "couldn't duplicate". Odd, since it did it as soon as I turned it on after I put the screws back in and tightened it all up. The only real way to compare (without any equipment) two radios is to hook them up to a coax switch and then to the same antenna, and switch them back and forth to compare. Sure there are many reasons a radio may not perform to specifications. Specifications can only get you so far. You do have to actually operate the radio to find out if its total performance is in line with your expectations. -- Telamon Ventura, California |
s-meter readings - drake r8 vs.palstar r30cc vs. kenwood r-5000.
On 4 Jan 2007 17:54:40 -0800, "john" wrote:
hi, i'm noticing a discrepancy between the s-meter readings of these three radios. all three radios are connected to the same antenna for the test and signals can be heard equally well on all three, but the kenwood r-5000 always has the highest signal levels, by quite a bit - followed by the palstar and then the drake. the palstar and the drake are the closest. when i turn the pre-amp on the drake closes in on the palstar, but still a little low. are s-meter readings standardized - is this a fair way to test for a radios sensitivity. The readings are more or less standardized... http://www.algonet.se/~k-jarl/ssa/IARU/smeter.html .... but the meterings can be "off" and in need of recalibration. bob k5qwg |
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