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Attenuation Questions
Hello,
Would you expect to see, in a practical sense, and meaningful difference between RG6 with a copper plated steel center conductor vs an all copper one, going from the antenna to a receiving scanner (50 foot run; 1 GHz max). Tried to find some attenuation tables for this in Google, but had no luck: Plenty for the coax cables themselves, but might you know of any chart links that show attenuation for the different types of connectors ? Thanks, B. |
Attenuation Questions
Robert11 wrote:
Hello, Would you expect to see, in a practical sense, and meaningful difference between RG6 with a copper plated steel center conductor vs an all copper one, going from the antenna to a receiving scanner (50 foot run; 1 GHz max). Tried to find some attenuation tables for this in Google, but had no luck: Plenty for the coax cables themselves, but might you know of any chart links that show attenuation for the different types of connectors ? No. Connector loss is negligible (0.1dB) for all reasonable connectors. The ohmic losses would be a tiny fraction of the ohmic loss in the cable itself (i.e. the connector interface is a few mm long, compared to meters of cable). Skin depth at 1 GHz in copper is 2 microns (0.08 mil). 6.5 microns (.26 mil) at 100 MHz. Your copper clad steel is probably just as good as solid copper (check the data sheet and see what the clad thickness is.. if it's 4-5 times the skin depth, it's the same as solid. Also check the shield material (there's more of it, but if it's aluminum, it's lower conductivity) At higher frequencies, dielectric loss will be a goodly fraction of the total cable loss. Again, the connector is very short, so its dielectric loss is a tiny fraction of the overall cable loss. |
Attenuation Questions
Robert11 wrote:
Hello, Would you expect to see, in a practical sense, and meaningful difference between RG6 with a copper plated steel center conductor vs an all copper one, going from the antenna to a receiving scanner (50 foot run; 1 GHz max). Tried to find some attenuation tables for this in Google, but had no luck: Plenty for the coax cables themselves, but might you know of any chart links that show attenuation for the different types of connectors ? Thanks, B. There will be no measurable electrical difference between copper clad steel and pure copper center conductor. There's no mechanism within any common type of RF connector which causes any significant amount of loss. Various types can cause some impedance mismatch, but not enough to cause a noticeable reduction of signal to the receiver. Roy Lewallen, W7EL |
Attenuation Questions
" There's no mechanism within any common type of RF connector which causes any significant amount of loss. Various types can cause some impedance mismatch, but not enough to cause a noticeable reduction of signal to the receiver. Since the OP was asking about frequencies up to 1GHz, I would be more cautious about losses in connectors. Poorly assembled connectors can show significant losses at 1GHz. Also I have come across connectors and adaptors (SMA) that show loss for no apparent reason at a Gig or so., now whether this is due to dielectric losses or some other factor I am not sure but mechanically they appeared to be prefect. One particular SMA barrel had a stable and repeatable loss of over 2dB, but was clean and gauged OK. Some of the cheap PL259 connectors also use very poor dielectric which show significant loss at even VHF. Regards Jeff |
Attenuation Questions
Jeff wrote:
" There's no mechanism within any common type of RF connector which causes any significant amount of loss. Various types can cause some impedance mismatch, but not enough to cause a noticeable reduction of signal to the receiver. Since the OP was asking about frequencies up to 1GHz, I would be more cautious about losses in connectors. Poorly assembled connectors can show significant losses at 1GHz. Also I have come across connectors and adaptors (SMA) that show loss for no apparent reason at a Gig or so., now whether this is due to dielectric losses or some other factor I am not sure but mechanically they appeared to be prefect. One particular SMA barrel had a stable and repeatable loss of over 2dB, but was clean and gauged OK. Some of the cheap PL259 connectors also use very poor dielectric which show significant loss at even VHF. Regards Jeff I'm surprised at these reports, but not too much except for the 2 dB connector. It must have had some internal corrosion, or perhaps something like a helical internal contact causing an impedance mismatch that would look like loss in a matched measurement system. (Some el crappo UHF barrel adapters have found to be constructed that way.) I've seen some awfully shoddy BNC connectors at ham conventions and wouldn't use them for anything at all critical. But the OP asked if there was a place he could find the losses of various kinds of connectors. I don't believe there's any place you can go to find the losses of shoddily made or improperly assembled connectors or adapters. Decently made and properly assembled connectors of standard types show no appreciable loss at 1 GHz. If loss is a concern, my advice is to buy name brand connectors, and especially avoid the cheap stuff you see at places like flea markets. Roy Lewallen, W7EL |
Attenuation Questions
In message , Roy Lewallen
writes Jeff wrote: " There's no mechanism within any common type of RF connector which causes any significant amount of loss. Various types can cause some impedance mismatch, but not enough to cause a noticeable reduction of signal to the receiver. Since the OP was asking about frequencies up to 1GHz, I would be more cautious about losses in connectors. Poorly assembled connectors can show significant losses at 1GHz. Also I have come across connectors and adaptors (SMA) that show loss for no apparent reason at a Gig or so., now whether this is due to dielectric losses or some other factor I am not sure but mechanically they appeared to be prefect. One particular SMA barrel had a stable and repeatable loss of over 2dB, but was clean and gauged OK. Some of the cheap PL259 connectors also use very poor dielectric which show significant loss at even VHF. Regards Jeff I'm surprised at these reports, but not too much except for the 2 dB connector. It must have had some internal corrosion, or perhaps something like a helical internal contact causing an impedance mismatch that would look like loss in a matched measurement system. (Some el crappo UHF barrel adapters have found to be constructed that way.) I've seen some awfully shoddy BNC connectors at ham conventions and wouldn't use them for anything at all critical. But the OP asked if there was a place he could find the losses of various kinds of connectors. I don't believe there's any place you can go to find the losses of shoddily made or improperly assembled connectors or adapters. Decently made and properly assembled connectors of standard types show no appreciable loss at 1 GHz. If loss is a concern, my advice is to buy name brand connectors, and especially avoid the cheap stuff you see at places like flea markets. Roy Lewallen, W7EL Even at 1GHz, I don't believe that you would get as much as 2dB of loss even if you joined two pieces of coax by stripping the ends with a knife, twisting the conductors together, and wrapping them in scotch tape. -- Ian |
Attenuation Questions
Hello,
First, let me say thanks to everyone for the replies and help. New at this, and it seems these very basic questions of mine keep coming up the more I look into it. Great hobby, and really do appreciate the help, very much. Super newsgroup for folks like me. Sure is a lot to learn re antennas; reading the ARRL book on it now. Would like to modify my question somewhat. Was really surprised to learn about the copper on steel, vs all copper center conductors on coax. I thought the difference were only in types of shielding; not center conductor construction, and that RG6, e.g., was RG6, at least concerning attenuation and perhaps "quality". Guess not ? I understand, and am aware of now, the skin effect depth Will read up on it some more. Question: any meaningful difference for the sw frequencies; say from 0.5 to 30 MHz ? I have a sw receiving set also, and frankly, when i strung my coax for it, I never considered the center conductor coax's construction. Should I have, possibly ? Thanks again, Bob ------------------- "Robert11" wrote in message . .. Hello, Would you expect to see, in a practical sense, and meaningful difference between RG6 with a copper plated steel center conductor vs an all copper one, going from the antenna to a receiving scanner (50 foot run; 1 GHz max). Tried to find some attenuation tables for this in Google, but had no luck: Plenty for the coax cables themselves, but might you know of any chart links that show attenuation for the different types of connectors ? Thanks, B. |
Attenuation Questions
I'm surprised at these reports, but not too much except for the 2 dB
connector. It must have had some internal corrosion, or perhaps something like a helical internal contact causing an impedance mismatch that would look like loss in a matched measurement system. (Some el crappo UHF barrel adapters have found to be constructed that way.) I've seen some awfully shoddy BNC connectors at ham conventions and wouldn't use them for anything at all critical. But the OP asked if there was a place he could find the losses of various kinds of connectors. I don't believe there's any place you can go to find the losses of shoddily made or improperly assembled connectors or adapters. Decently made and properly assembled connectors of standard types show no appreciable loss at 1 GHz. If loss is a concern, my advice is to buy name brand connectors, and especially avoid the cheap stuff you see at places like flea markets. Roy Lewallen, W7EL Even at 1GHz, I don't believe that you would get as much as 2dB of loss even if you joined two pieces of coax by stripping the ends with a knife, twisting the conductors together, and wrapping them in scotch tape. -- Ian The items in question were SMA barrel adaptors and as I said showed no signs of damage, corrosion or spreading of the contacts and interface dimensions were in spec It is surprisingly easy to get significant loss at 1GHz and above, 2dB would be very easy to achieve even when using what appears to be a 'good' connection. regards Jeff |
Attenuation Questions
In message , Jeff
writes I'm surprised at these reports, but not too much except for the 2 dB connector. It must have had some internal corrosion, or perhaps something like a helical internal contact causing an impedance mismatch that would look like loss in a matched measurement system. (Some el crappo UHF barrel adapters have found to be constructed that way.) I've seen some awfully shoddy BNC connectors at ham conventions and wouldn't use them for anything at all critical. But the OP asked if there was a place he could find the losses of various kinds of connectors. I don't believe there's any place you can go to find the losses of shoddily made or improperly assembled connectors or adapters. Decently made and properly assembled connectors of standard types show no appreciable loss at 1 GHz. If loss is a concern, my advice is to buy name brand connectors, and especially avoid the cheap stuff you see at places like flea markets. Roy Lewallen, W7EL Even at 1GHz, I don't believe that you would get as much as 2dB of loss even if you joined two pieces of coax by stripping the ends with a knife, twisting the conductors together, and wrapping them in scotch tape. -- Ian The items in question were SMA barrel adaptors and as I said showed no signs of damage, corrosion or spreading of the contacts and interface dimensions were in spec It is surprisingly easy to get significant loss at 1GHz and above, 2dB would be very easy to achieve even when using what appears to be a 'good' connection. regards Jeff I have to admit that I've routinely worked to 870MHz, and recently even to 1003MHz, but rarely ventured higher. However, I've never found any excessive loss in a connector which could not be accounted for by a straightforward 'bad connection', ie usually a total or partial open or short circuit, whether in the making off of the cable, or in the construction of the connector itself. Honest! -- Ian. |
Attenuation Questions
Ian Jackson wrote in
: In message , Jeff writes I'm surprised at these reports, but not too much except for the 2 dB connector. It must have had some internal corrosion, or perhaps something like a helical internal contact causing an impedance mismatch that would look like loss in a matched measurement system. (Some el crappo UHF barrel adapters have found to be constructed that way.) I've seen some awfully shoddy BNC connectors at ham conventions and wouldn't use them for anything at all critical. But the OP asked if there was a place he could find the losses of various kinds of connectors. I don't believe there's any place you can go to find the losses of shoddily made or improperly assembled connectors or adapters. Decently made and properly assembled connectors of standard types show no appreciable loss at 1 GHz. If loss is a concern, my advice is to buy name brand connectors, and especially avoid the cheap stuff you see at places like flea markets. Roy Lewallen, W7EL snip I have to admit that I've routinely worked to 870MHz, and recently even to 1003MHz, but rarely ventured higher. However, I've never found any excessive loss in a connector which could not be accounted for by a straightforward 'bad connection', ie usually a total or partial open or short circuit, whether in the making off of the cable, or in the construction of the connector itself. Honest! One thing, SMA connectors are rated for 500 connection cycles, I don’t know what happens after that, but on test equipment 500 connections might happen fairly fast. I know from experience that SMA is a connector that’s easy to put on badly. John Passaneau |
Attenuation Questions
On Tue, 11 Mar 2008 16:00:11 +0000, Ian Jackson
wrote: Even at 1GHz, I don't believe that you would get as much as 2dB of loss even if you joined two pieces of coax by stripping the ends with a knife, twisting the conductors together, and wrapping them in scotch tape. -- Ian It is surprisingly easy to get significant loss at 1GHz and above, 2dB would be very easy to achieve even when using what appears to be a 'good' connection. regards Jeff I have to admit that I've routinely worked to 870MHz, and recently even to 1003MHz, but rarely ventured higher. However, I've never found any excessive loss in a connector which could not be accounted for by a straightforward 'bad connection', ie usually a total or partial open or short circuit, whether in the making off of the cable, or in the construction of the connector itself. Honest! Hi All, Anyone can do it wrong (come up with 2dB loss), but we would have a great more deal traffic here if doing it wrong was that common. I have measured attenuation of near everything from DC to 12GHz at the standards bench and RG58 with BNCs for a short run (2 to 3 meters) never presented any problems being wildly imagined here. At the worst, the connectors (note plural) "might" show 0.2dB mismatch loss - trivial. On the other hand, if Jeff is so sure of this 2dB figure, it should reveal itself in blisters to the fingers for even mild power (100W). Since this unequivocal evidence is so obviously missing from the records (or the testimony, as the case may be); then it is very apparently one of those "someone heard from someone else about their brother's friend's boss who had a customer who made this claim." 73's Richard Clark, KB7QHC |
Attenuation Questions
Robert11 wrote:
Hello, First, let me say thanks to everyone for the replies and help. New at this, and it seems these very basic questions of mine keep coming up the more I look into it. Great hobby, and really do appreciate the help, very much. Super newsgroup for folks like me. Sure is a lot to learn re antennas; reading the ARRL book on it now. Would like to modify my question somewhat. Was really surprised to learn about the copper on steel, vs all copper center conductors on coax. I thought the difference were only in types of shielding; not center conductor construction, and that RG6, e.g., was RG6, at least concerning attenuation and perhaps "quality". Guess not ? I understand, and am aware of now, the skin effect depth Will read up on it some more. Question: any meaningful difference for the sw frequencies; say from 0.5 to 30 MHz ? I have a sw receiving set also, and frankly, when i strung my coax for it, I never considered the center conductor coax's construction. Should I have, possibly ? Thanks again, Bob Any quality coax will have a sufficiently thick copper coating on the center conductor to insure that the current is, for practical purposes, always in the copper rather than the steel down to quite a low frequency. If the plating were unusually thin, the current would penetrate into the steel at lower frequencies and the loss would be much greater. However, loss in a transmission line used for receiving only becomes very much less important at HF and below (that is, below about 30 MHz). So the bottom line is that it's not normally anything you need to worry about. A copper plated steel conductor is used to increase the physical strength of the cable, particularly cables of smaller diameter and higher impedance, where the diameter of the center conductor becomes small. When done properly (as it usually is), it works just the same electrically as a solid copper conductor. The _ARRL Antenna Book_ is a very good place to start in learning about antennas. Roy Lewallen, W7EL |
Attenuation Questions
Anyone can do it wrong (come up with 2dB loss), but we would have a great more deal traffic here if doing it wrong was that common. I have measured attenuation of near everything from DC to 12GHz at the standards bench and RG58 with BNCs for a short run (2 to 3 meters) never presented any problems being wildly imagined here. At the worst, the connectors (note plural) "might" show 0.2dB mismatch loss - trivial. On the other hand, if Jeff is so sure of this 2dB figure, it should reveal itself in blisters to the fingers for even mild power (100W). Since this unequivocal evidence is so obviously missing from the records (or the testimony, as the case may be); then it is very apparently one of those "someone heard from someone else about their brother's friend's boss who had a customer who made this claim." 73's Richard Clark, KB7QHC Well let me put you right Richard, there was no high power, so burnt fingers, this was noticed in a test set-up on a network analyser, and subsequently the adaptors in question were tested in isolation. 'Good' adaptors were also substituted and their loss was measured and was very low indeed. The problem was first noticed by a very senior consultant in the lab in question and then checked by several other people because they could not believe it either. The connector interfaces were checked and were Ok. No further time was spent investigating why the problem occurred, just 2 SMA adaptors in the bin and the rest of the adaptors in the lab checked. So please don't denigrate other people's comment without asking about the facts. My comments were not about properly made connectors, that will have very low loss, but were a caution that at high UHF and above care has to be taken and it is very easy to introduce loss. This is particularly the case when launching from connectors onto pc boards with microstrip or joining on to coax cable. Having been involved professionally for over 10 years in the design of microwave equipment I can assure you that there is an endless list of the ways that loss can creep into a system at high frequencies. 73 Jeff |
Attenuation Questions
Jeff wrote:
. . . My comments were not about properly made connectors, that will have very low loss, but were a caution that at high UHF and above care has to be taken and it is very easy to introduce loss. This is particularly the case when launching from connectors onto pc boards with microstrip or joining on to coax cable. Having been involved professionally for over 10 years in the design of microwave equipment I can assure you that there is an endless list of the ways that loss can creep into a system at high frequencies. I sense a communication problem here. "Loss" usually implies dissipation of some of the desired power in the form of heat, and that's the way I use the term. However, people who spend a lot of time in a test equipment environment often use the term to mean loss as described above, "mismatch loss", or some combination of the two. And I've often seen people mistake "mismatch loss" for dissipative loss. But it's important to separate the two, since they have different causes and cures. Dissipative loss is caused by current flowing through a resistance, which causes power in the amount of I^2 * R being lost as heat. When dealing with dielectric loss, it's often easier to calculate it as V^2 / R. The mechanism is somewhat different but the end result, dissipation, is the same. "Mismatch loss" is entirely different, although someone making measurements with a network analyzer or other test system won't readily be able to distinguish it from dissipative loss. "Mismatch loss" works like this: Suppose we have a signal generator with a 50 ohm fixed resistive output impedance which delivers 1 watt to a resistive 50 ohm load. If we were to insert, say, an inductor with a reactance of 100 ohms in series between the source and load, only 500 mW will be delivered to the 50 ohm load. Now, this is for a lossless inductor, so there's no dissipative loss in the inductor. Yet the inductor is said to have an "insertion loss" of 10 * log(1/0..5) ~ 3 dB because the amount of power delivered to the load is less than the amount which would be delivered under matched conditions. Consider another example -- a perfect, lossless transformer is inserted between the generator and 50 ohm load. If the transformer has a 2:1 turns ratio (4:1 impedance ratio), 640 mW will be delivered to the 50 ohm load. So the transformer is said to have an "insertion loss" of ~ 1.9 dB. The way to reduce dissipative loss is to reduce the I^2 * R or V^2 / R product one way or another. Power companies do this by raising the voltage for long distance transmission, thereby reducing I. We often use a larger diameter coaxial feedline, which reduces the conductor R -- or use an open wire line which reduces I because of its higher characteristic impedance. "Mismatch loss" can be eliminated entirely by adding an impedance matching network. In the examples above, a matching network anywhere between the generator and load which causes the generator to see 50 ohms resistive will reduce the "mismatch loss" to zero -- that is, it will raise the power in the load resistor back to its maximum possible value of 1 watt. Now when Jeff says that loss can be introduced by coax-to-microstrip transitions, he's speaking of "mismatch loss", not dissipative loss. There's no mechanism which would cause the I, V, or R to become high enough in the region of a transition to cause an appreciable amount of dissipative loss. It is, however, extremely difficult to make a transition which doesn't introduce a different impedance in the transition region. (And it's very nearly always a higher, or inductive, impedance due to the fields escaping or fringing from the regions immediately between the conductors.) I'm very familiar with this, having designed transitions which had to maintain the proper impedance from DC into the tens of GHz for very sensitive time domain equipment. It can, however, usually be compensated by introducing complementary impedances in the immediate vicinity -- this is the equivalent to providing an impedance match. The result is a clean transition with negligible loss -- "mismatch" or otherwise. It's not possible to compensate for dissipative loss in this way. If such a transition shows loss in a network analyzer measurement, for example, it's almost surely "mismatch loss" and not dissipative loss. It won't burn anyone's fingers if a kW is applied, and the cure wouldn't help dissipative loss at all. "Mismatch loss" is useful mostly to people who have to stay in a fixed 50 ohm environment with no opportunity to apply impedance matching. That's not usually the case in amateur antenna systems. So when someone, especially someone with a test laboratory background, says "loss", it's important to ask whether they mean dissipative loss or "mismatch loss", since we can make the latter disappear but not the former. So, I'll ask: Was the 2 dB connector loss dissipative (caused by an exceptionally high resistance series conductor and/or exceptionally lossy dielectric), or was it "mismatch loss" (caused by a dramatic impedance change within the connector due to a changed relationship between conductors -- say, missing dielectric or something like a helical conductor)? Roy Lewallen, W7EL |
Attenuation Questions
Snip
" So, I'll ask: Was the 2 dB connector loss dissipative (caused by an exceptionally high resistance series conductor and/or exceptionally lossy dielectric), or was it "mismatch loss" (caused by a dramatic impedance change within the connector due to a changed relationship between conductors -- say, missing dielectric or something like a helical conductor)? Roy Lewallen, W7EL A good question Roy, but I cannot answer it, other than to say that the SMA interfaces were clean and apparently dimensionally in spec.. There was not the time or money to investigate further, the adaptors just went in the bin! (they were good quality adaptors by the way, probably MA/com). 73 Jeff |
Attenuation Questions
Richard Clark wrote:
On Tue, 11 Mar 2008 16:00:11 +0000, Ian Jackson wrote: Even at 1GHz, I don't believe that you would get as much as 2dB of loss even if you joined two pieces of coax by stripping the ends with a knife, twisting the conductors together, and wrapping them in scotch tape. -- Ian It is surprisingly easy to get significant loss at 1GHz and above, 2dB would be very easy to achieve even when using what appears to be a 'good' connection. regards Jeff Hi All, Anyone can do it wrong (come up with 2dB loss), but we would have a great more deal traffic here if doing it wrong was that common. I have measured attenuation of near everything from DC to 12GHz at the standards bench and RG58 with BNCs for a short run (2 to 3 meters) never presented any problems being wildly imagined here. At the worst, the connectors (note plural) "might" show 0.2dB mismatch loss - trivial. On the other hand, if Jeff is so sure of this 2dB figure, it should reveal itself in blisters to the fingers for even mild power (100W). Since this unequivocal evidence is so obviously missing from the records (or the testimony, as the case may be); then it is very apparently one of those "someone heard from someone else about their brother's friend's boss who had a customer who made this claim." 73's Richard Clark, KB7QHC I've encountered (defective or broken) SMA hardware that has remarkably high *apparent* loss. Typically, internal cracks or voids. I had a batch of Pasternack right angle M-F elbows that had losses that were all over the place at 1 GHz sorts of frequencies. I'm pretty sure that internally, there was something not connected, or a spring loaded something that wasn't making contact. In this case, the connector wasn't actually lossy, but more of an extreme mismatch, and when hooked up with a 50 ohm signal generator on one side and a 50 ohm power meter on the other, it looked like loss. Actually, it was reflecting the power back to the source. In this scenario, with 100W, your fingers wouldn't have gotten burned (but the signal generator would probably shut down with reverse power warnings) |
Attenuation Questions
On Wed, 12 Mar 2008 08:36:12 -0000, "Jeff" wrote:
So please don't denigrate other people's comment without asking about the facts. Hi Jeff, Well, in fact, facts were preciously few and generalities were liberally asserted. I read facts attesting to "significant loss" and indicated that it should be attended by heat where in my experience (and as the head of an RF metrology lab) these connector issues far more commonly exhibit mismatch loss (and I chose my words with care) not "significant loss." Bird Wattmeter connectors suffer from this very problem and I have outlined that in the past. Bob asked about receive properties and RG6 where BNC or N applications would be typically found for operation above 150 MHz. My response with respect to cables (plural) of a short length and terminated with on-par connectors (plural) indicate that loss (insertion loss both as dissipative and mismatch) is principally invested in the cable, not the connector. RCA or F or PL types are not taken seriously in the real world - but they would work suitably for receive. My personal limitation to 2 or 3 meter lengths were for jumpers application. My personal limitation to 1GHz for BNC was for leakage issues, not loss. BNCs/TNCs are rated to 4GHz and N higher to 12GHz. Bob can then research cable which has far more specification available on the web. Abstracting a one-off problem with a barrel connector into general cautions about issues of dielectric quality brings to mind that one data point does not denote a trend. An SMA/RG6 combination is not one that springs automatically to mind; neither does an SMA/50 foot line (presumably RG174 - even though I would do it in spite of demurring it as a solution). For 50 feet, and considering the receiver and the service, and the link budget, none of this probably matters (not even 2dB). If this is for EME, then yes, it matters a lot. Bob didn't indicate EME. 73's Richard Clark, KB7QHC |
Attenuation Questions
On Wed, 12 Mar 2008 11:55:35 -0700, Jim Lux
wrote: I've encountered (defective or broken) SMA hardware that has remarkably high *apparent* loss. Hi Jim, Modifiers abound, and such an abundance generally suggest there are problems of understanding. Roy and I have already written to that matter. Returning to poor connectors, the cables that I gathered for jumpers at the RF bench were selected, naturally. We had plenty to choose from, but there were always poor performers for any of a number of reasons we didn't care to investigate, simply because we tossed the losers. Insertion loss was never a problem as long as it was constant. The losers did not present a constant insertion loss which could have been attributal to connector quality (or construction quality); but some times there seemed to be the suggestion of triboelectric effect (cable bending not associated with straining the connector). Anyway, the cables were tossed without too much regard for why - we had better things to do (the in shelves never seem to empty). 73's Richard Clark, KB7QHC |
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