What is a db worth?
Well, t's like alcoholism. What are you willing to give up for your hobby
addiction?
What is your family and your dog willing to give up for your addiction
before they file for divorce?
You can't ALWAYS put a dollar value on it. At least until the lawyer slaps
you with his invoice. And the judge slaps you with the settlement. Which
means that you may not have a ham shack any more. You may need to buy a
cheap RV and go ham mobile.
Dan Schaaf
K3ZXL
"In the Beginning there was Spark Gap"
www.k3zxl.com
----- Original Message -----
From: "Stephen Davis" <sdavis@davisrf.com>
To: <towertalk@contesting.com>
Cc: <mwbesemer@cox.net>; "Roger (K8RI)" <k8ri-on-towertalk@tm.net>
Sent: Friday, February 12, 2010 12:48 AM
Subject: Re: [TowerTalk] Measuring Coax Loss-Dealers - Response DAVIS RF
>A brief response to some TT'rs observations herein:
>
> What's a dB worth:
> As much as you can afford to spend to achieve your desired result,
> without short changing the rest of the family...a distinct point of
> "diminishing (moral?) return".
>
> 3 dB + or - :
> Definitely a "difference". Particularly important as to relevance to
> S/N; ur receiver's performance; and that of your hearing (this is not to
> insinuate that any TT'r comment herein is based on poor/exc hearing or
> having a poor/exc receiver).
>
> Too many connectors in the transmission line:
> Figure it like this, the connectors I deal in, as most quality
> connectors, have an insertion loss of .200 dB NOTE: AT THE MUF OF THE
> CONNECTOR. These UHF connectors have
> an MUF of 300 MHz. The insertion loss / freqcy is linear....easy math, @
> 3 MHz insertion is .002 dB.
> And yes, UHF's "work" at > 300 MHz...300 is the generally accepted
> practical/efficient MUF.
>
> Dealers that may or may not know the significance of specs or testing and
> QC of cables they sell:
> True, so pick a dealer who knows his stuff, designs various cables;
> also qualifies and sells to entities such as NASA; Lockheed Martin;
> SPAWAR; US Military; etc.,; also wholesales to hams; contributes to DX
> petitions; and has at least one ham on staff (what more could you want
> HI).
>
> 73, Steve K1PEK
>
> Davis RF Company
> Electronic Wire, Cable and Cable Design Engineering
> RF Coaxial Cable Connectors and Telecom Parts
> A Division of Orion Wire Company, Inc.
> www.DavisRF.com
>
> Main office, NH: Tel: 1-800-DAVIS RF
> Steve Davis, Direct line, MA Branch: 1-978-369-1738 sdavis@DavisRF.com
>
>
>
>>
>>
>> 2. Re: Measuring Coax Loss (Roger (K8RI))
>> 3. Re: Measuring Coax Loss (Tom Osborne)
>> 4. Re: Measuring Coax Loss (Roger (K8RI))
>> 5. Re: Measuring Coax Loss (Mike)
>>
>>
>> ----------------------------------------------------------------------
>>
>>
>>
>> Message: 2
>> Date: Thu, 11 Feb 2010 22:55:13 -0500
>> From: "Roger (K8RI)" <K8RI-on-TowerTalk@tm.net>
>> Subject: Re: [TowerTalk] Measuring Coax Loss
>> To: "Tower and HF antenna construction topics."
>> <towertalk@contesting.com>
>> Message-ID: <4B74D121.5030500@tm.net>
>> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>>
>>
>>
>> Mike Besemer (WM4B) wrote:
>>> But let's put it in perspective.
>>>
>>> Suppose you're putting up a new antenna system and have two 100' lengths
>>> of
>>> coax to choose from, one of which has 1dB more loss than the other.
>>>
>>> How much is that 1dB worth to you? 10 cents/foot? 20? 50? Suppose
>>> you
>>> have to make the same choice for 4 or 5 runs of the same coax. Where do
>>> you
>>> draw the line?
>>>
>>> I certainly get your point... I think the question is, where is the
>>> point of
>>> diminishing returns?
>>>
>>>
>> I think it's not the point of diminishing returns but rather what
>> compromise is the individual willing to settle for. IOW would you pay $1
>> more per foot, $2.00, $3.00, $5.00, or where would the individual draw
>> the line on those diminishing returns. I started with good RG-8, then
>> went to 9913, then LMR-400, and currently with LMR-600. Next step? 7/8"
>> Heliax for each run to the tower and up the tower? Probably if I come
>> across some at a good price...IE, pull out from a commercial station
>> that's been swept. How much are you willing to spend for power? You can
>> get the legal limit for close to $1000 used and go all the way to an
>> auto tuning alpha that runs close to ten grand. Is the $800 plus Yaesu
>> 897D good enough or are you willing to go $13,000 for their best
>> transceiver. What if you spend at least as much time in your shop as the
>> house like I do. Would you get the versatility of the 897D and carry it
>> back and fourth, get two of them and spend the bucks to set up a SO2R
>> station? I've had both the 897D and the 7000. Hated them both although
>> they'd make great mobile rigs.
>>
>> Like many on here, my interest is in antennas, towers, and feed lines
>> and *probably* most of us would spend more on the antenna and feed line
>> than is installed in the typical station.
>>
>> Some individuals would spend big bucks to get that 1 db. I really need
>> to put the story up about WD8RXP's home brew, self supporting tower.
>> The story was in QST (I had the cover shot) as the "Mid Michigan
>> Skyhook" written by Norm Keyon (WA8AEG) now W8AWE. IIRC John had
>> something like three semi loads of steel in that tower and over $30,000.
>> John passed away a few years back and they couldn't even give the tower
>> away. It was even on e-bay with no bids. That system was small potatoes
>> compared to some that have been listed on here such as those self
>> supporting towers large enough to support a 4L 75 meter beam large
>> enough to walk "inside" the boom. Add to that the extra money for a
>> big beam...say monobander and the structure to support and turn it for
>> another db. Suppose the individual is willing to take the risk of not
>> grounding the coax at the top and bottom of the tower so they eliminate
>> the cost and loss (a few tenths of a db) for those extra connectors
>> who's sole purpose is safety. They could be putting their entire station
>> on the line just for a few tenths of a db.
>>> I have a different perspective. Aside from my time when I was a kid, I
>>> never had a 'decent' antenna system. I moved every couple of years for
>>> the
>>> 24 of the past 29 years. I used low wires and whatever else I could put
>>> up.
>>> I have confirmed over 200 countries and never applied for DXCC because
>>> it's
>>> not important to me.
>>>
>>> How much would I pay for that extra dB? Not a cent.
>>>
>> I think that is one of the great things about ham radio. You can put
>> into it what you want and you and strive to get out of it what you wish.
>> There is a place for virtually every budget. income, and most
>> personalities. There are probably as many answers to the original
>> question of what would you spend for that extra db as there are
>> hundreds,or possibly over a thousand who are on, or follow Tower Talk. I
>> would add to the question as to how much more would you be willing to
>> spend, "how much extra work, and why".
>>
>> 73
>>
>> Roger (K8RI)
>>>
>>>
>>> -----Original Message-----
>>> From: towertalk-bounces@contesting.com
>>> [mailto:towertalk-bounces@contesting.com] On Behalf Of Dan Schaaf
>>> Sent: Thursday, February 11, 2010 8:33 PM
>>> To: Tower and HF antenna construction topics.
>>> Subject: Re: [TowerTalk] Measuring Coax Loss
>>>
>>> I spend most of my waking hours working DX. And since I have worked 308
>>> countries on most bands, I hunt for those that I have not yet worked on
>>> certain bands. Tonite for example I worked DU9 on 15 meters SSB. Koichi
>>> was
>>> just above the noise except for some QSB when he dropped in/out. Most of
>>> what I need is weak. I did the 308 countries during the last 5 years
>>> when
>>> the SSN was in decline.
>>>
>>> Best Regards
>>> Dan Schaaf
>>> K3ZXL www.k3zxl.com "In the Beginning, there was Spark Gap"
>>> ===============================
>>> NOBSKA
>>> www.nobska.net
>>> ===============================
>>> Cape Cod Instruments
>>> www.oceanbiz.net
>>> ===============================
>>> ----- Original Message -----
>>> From: "Mike Besemer (WM4B)" <mwbesemer@cox.net>
>>> To: "'Tower and HF antenna construction topics.'"
>>> <towertalk@contesting.com>
>>> Sent: Thursday, February 11, 2010 8:26 PM
>>> Subject: Re: [TowerTalk] Measuring Coax Loss
>>>
>>>
>>>
>>>> How, it the real world of ham radio, do you experience hearing the
>>>> difference of 3dB daily?
>>>>
>>>> I'm not talking about a lab.
>>>>
>>>>
>>>>
>>>> -----Original Message-----
>>>> From: towertalk-bounces@contesting.com
>>>> [mailto:towertalk-bounces@contesting.com] On Behalf Of Dan Schaaf
>>>> Sent: Thursday, February 11, 2010 8:24 PM
>>>> To: Tower and HF antenna construction topics.
>>>> Subject: Re: [TowerTalk] Measuring Coax Loss
>>>>
>>>> I am not " thinking what I want". I know this to be fact.
>>>> I experience it daily.
>>>> Nobody is disqualifying you or accusing you of stupidity. There is a
>>>> difference between stupidity and ignorance. Ignorance is "not knowing
>>>> or
>>>> not
>>>>
>>>> having been educated". Stupidity is knowing and still being defiant of
>>>> the
>>>> knowledge.
>>>> You come to this and other groups for knowledge.
>>>>
>>>>
>>>> Best Regards
>>>> Dan Schaaf
>>>> K3ZXL www.k3zxl.com "In the Beginning, there was Spark Gap"
>>>> ===============================
>>>> NOBSKA
>>>> www.nobska.net
>>>> ===============================
>>>> Cape Cod Instruments
>>>> www.oceanbiz.net
>>>> ===============================
>>>> ----- Original Message -----
>>>> From: "Mike Besemer (WM4B)" <mwbesemer@cox.net>
>>>> To: "'Tower and HF antenna construction topics.'"
>>>> <towertalk@contesting.com>
>>>> Sent: Thursday, February 11, 2010 8:13 PM
>>>> Subject: Re: [TowerTalk] Measuring Coax Loss
>>>>
>>>>
>>>>
>>>>> Think what you want, Dan... I stand by my argument that 99% of the
>>>>> time
>>>>> 3dB
>>>>> is inaudible.
>>>>>
>>>>> I love the sanctimonious attitude on this list. If somebody
>>>>> disagrees,
>>>>> they're automatically unqualified or stupid.
>>>>>
>>>>> That's why I left last time.
>>>>>
>>>>>
>>>>> -----Original Message-----
>>>>> From: towertalk-bounces@contesting.com
>>>>> [mailto:towertalk-bounces@contesting.com] On Behalf Of Dan Schaaf
>>>>> Sent: Thursday, February 11, 2010 8:07 PM
>>>>> To: Tower and HF antenna construction topics.
>>>>> Subject: Re: [TowerTalk] Measuring Coax Loss
>>>>>
>>>>> A really serious DXer is concerned about these losses.
>>>>> Someone who casually operates may not care too much.
>>>>> The point is that all losses add up.
>>>>> I CAN hear the difference.
>>>>> For example. +/- 3 db is either 1/2 or 2 x the power whether
>>>>> transmitted
>>>>> or
>>>>>
>>>>> received. I can clearly hear the difference in a weak signal if
>>>>> itdrops3
>>>>> db
>>>>>
>>>>> or raises 3 db.
>>>>> I think that you are just repeating something that you heard and have
>>>>> not
>>>>> actually experienced these differences on the air.
>>>>>
>>>>>
>>>>> Best Regards
>>>>> Dan Schaaf
>>>>> K3ZXL www.k3zxl.com "In the Beginning, there was Spark Gap"
>>>>> ===============================
>>>>> NOBSKA
>>>>> www.nobska.net
>>>>> ===============================
>>>>> Cape Cod Instruments
>>>>> www.oceanbiz.net
>>>>> ===============================
>>>>> ----- Original Message -----
>>>>> From: "Mike Besemer (WM4B)" <mwbesemer@cox.net>
>>>>> To: "'Tower and HF antenna construction topics.'"
>>>>> <towertalk@contesting.com>
>>>>> Sent: Thursday, February 11, 2010 8:01 PM
>>>>> Subject: Re: [TowerTalk] Measuring Coax Loss
>>>>>
>>>>>
>>>>>
>>>>>> I qualified my comments to exclude microwave/weak signal work.
>>>>>>
>>>>>> If you have that many connectors in-line, how concerned are you
>>>>>> REALLY
>>>>>> about
>>>>>> loss?
>>>>>>
>>>>>> C'mon guys... for HF and probably VHF, it isn't that critical.
>>>>>>
>>>>>> WM4B
>>>>>>
>>>>>> -----Original Message-----
>>>>>> From: towertalk-bounces@contesting.com
>>>>>> [mailto:towertalk-bounces@contesting.com] On Behalf Of Dan Schaaf
>>>>>> Sent: Thursday, February 11, 2010 7:45 PM
>>>>>> To: Tower and HF antenna construction topics.
>>>>>> Subject: Re: [TowerTalk] Measuring Coax Loss
>>>>>>
>>>>>> Having been a calibration Engineer in my early days, I concur with
>>>>>> Jim.
>>>>>> In addition, each coax connector inline introduces losses. They all
>>>>>> add
>>>>>> up.
>>>>>> Definitely worse in VHF/UHF. Some folks say you can't hear the
>>>>>> difference,
>>>>>> but when you are trying to hear and work a weak signal in/above the
>>>>>> noise,
>>>>>> every db counts.
>>>>>>
>>>>>> Dan Schaaf
>>>>>> K3ZXL
>>>>>> "In the Beginning there was Spark Gap"
>>>>>> www.k3zxl.com
>>>>>> ----- Original Message -----
>>>>>> From: "Jim Brown" <jim@audiosystemsgroup.com>
>>>>>> To: "Tower and HF antenna construction topics."
>>>>>> <towertalk@contesting.com>
>>>>>> Sent: Thursday, February 11, 2010 7:34 PM
>>>>>> Subject: Re: [TowerTalk] Measuring Coax Loss
>>>>>>
>>>>>>
>>>>>>
>>>>>>> On Thu, 11 Feb 2010 19:03:51 -0500, Mike Besemer \(WM4B\) wrote:
>>>>>>>
>>>>>>>
>>>>>>>> Still... a dB or so (or even 3) on a long run of coax isn't going
>>>>>>>> to
>>>>>>>> make a hill of beans difference for most applications... an S-Unit
>>>>>>>> is ~ 6dB.
>>>>>>>>
>>>>>>> Only by someone's definition, not in reality. If you actually
>>>>>>> MEASURE
>>>>>>> the
>>>>>>> response of the S-meters in REAL radios, you find that an S-unit may
>>>>>>> be
>>>>>>> close
>>>>>>> to 6dB near S9, but is usually closer to 3dB at S5 and below.
>>>>>>>
>>>>>>> As to a hill of beans -- many hams have long runs of coax to their
>>>>>>> antennas,
>>>>>>> so loss can be a BIG deal, not a hill of beans. The loss in dB of
>>>>>>> verious
>>>>>>> RG8
>>>>>>> style coaxes ranges by a factor of about 2:1 from the lowest to the
>>>>>>> highest.
>>>>>>> Over the past several years, I've been doing a lot of little things
>>>>>>> to
>>>>>>> improve my station. A dB here, a dB there, they all add up. Smart
>>>>>>> operators
>>>>>>> know that. The difference between a 3-el yagi and a 4-el yagi of
>>>>>>> comparable
>>>>>>> design is only 1-2 dB, and often double the cost. That doesn't stop
>>>>>>> a
>>>>>>> lot
>>>>>>> of
>>>>>>> guys who have the space from putting up 4-el yagis!
>>>>>>>
>>>>>>> Somehow, the scientific method seems to be lost on some of those
>>>>>>> commenting
>>>>>>> on my post. How do you know that the MFJ (or any piece of test gear)
>>>>>>> is
>>>>>>> accurate if you don't compare it to another measurement or test
>>>>>>> method
>>>>>>> of
>>>>>>> known accuracy? I'll bet a six pack of your favorite 807s that if I
>>>>>>> had
>>>>>>> posted loss measuerements made ONLY with an MFJ, someone would have
>>>>>>> pooh-
>>>>>>> poohed them because I didn't use equipment traceable to a
>>>>>>> calibration
>>>>>>> lab.
>>>>>>>
>>>>>>>
>>>>>>>> Forgot to mention... unless I actually SAW the 10' piece being cut
>>>>>>>> off
>>>>>>>> the
>>>>>>>> longer roll I was considering buying from, I wouldn't trust the
>>>>>>>> measurements
>>>>>>>> anyway.
>>>>>>>>
>>>>>>> Did it ever occur to you that sometimes ham stores, even the best
>>>>>>> known,
>>>>>>> with
>>>>>>> the biggest ads in QST, may not have good data on what they're
>>>>>>> selling?
>>>>>>> I
>>>>>>> don't trust some of them any more than an anonymous vendor in a flea
>>>>>>> market.
>>>>>>> But there ARE some good deals out there, IF you have an open mind
>>>>>>> and
>>>>>>> know
>>>>>>> how to evaluate them. The point of my post was to show that you CAN
>>>>>>> get
>>>>>>> decent data from an MFJ259B that has been calibrated if you're
>>>>>>> measuring
>>>>>>> a
>>>>>>> sample that is long enough.
>>>>>>>
>>>>>>> How many measurements of coax loas have you actually made? How did
>>>>>>> you
>>>>>>> do
>>>>>>> it?
>>>>>>> How did you know that you had good data? At some point, you've got
>>>>>>> to
>>>>>>> know
>>>>>>> exactly how long that piece of coax is. RG8 is big and heavy, so
>>>>>>> unspooling
>>>>>>> enough of it to get a good measurement isn't always easy. You've got
>>>>>>> to
>>>>>>> deal
>>>>>>> with the length of cable sample you can get.
>>>>>>>
>>>>>>> 73,
>>>>>>>
>>>>>>> Jim K9YC
>>>>>>>
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> TowerTalk mailing list
>>>>>>> TowerTalk@contesting.com
>>>>>>> http://lists.contesting.com/mailman/listinfo/towertalk
>>>>>>>
>>>>>> _______________________________________________
>>>>>>
>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> TowerTalk mailing list
>>>>>> TowerTalk@contesting.com
>>>>>> http://lists.contesting.com/mailman/listinfo/towertalk
>>>>>>
>>>>>> _______________________________________________
>>>>>>
>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> TowerTalk mailing list
>>>>>> TowerTalk@contesting.com
>>>>>> http://lists.contesting.com/mailman/listinfo/towertalk
>>>>>>
>>>>> _______________________________________________
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> TowerTalk mailing list
>>>>> TowerTalk@contesting.com
>>>>> http://lists.contesting.com/mailman/listinfo/towertalk
>>>>>
>>>>> _______________________________________________
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> TowerTalk mailing list
>>>>> TowerTalk@contesting.com
>>>>> http://lists.contesting.com/mailman/listinfo/towertalk
>>>>>
>>>> _______________________________________________
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> TowerTalk mailing list
>>>> TowerTalk@contesting.com
>>>> http://lists.contesting.com/mailman/listinfo/towertalk
>>>>
>>>> _______________________________________________
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> TowerTalk mailing list
>>>> TowerTalk@contesting.com
>>>> http://lists.contesting.com/mailman/listinfo/towertalk
>>>>
>>>
>>>
>>> _______________________________________________
>>>
>>>
>>>
>>> _______________________________________________
>>> TowerTalk mailing list
>>> TowerTalk@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/towertalk
>>>
>>> _______________________________________________
>>>
>>>
>>>
>>> _______________________________________________
>>> TowerTalk mailing list
>>> TowerTalk@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/towertalk
>>>
>>>
>>
>>
>> ------------------------------
>>
>> Message: 3
>> Date: Thu, 11 Feb 2010 19:55:56 -0800
>> From: "Tom Osborne" <w7why@verizon.net>
>> Subject: Re: [TowerTalk] Measuring Coax Loss
>> To: "Tower and HF antenna construction topics."
>> <towertalk@contesting.com>
>> Message-ID: <E0AEC22C7DAF4CA3B79AC728BD8CB298@Tom>
>> Content-Type: text/plain; format=flowed; charset=iso-8859-1;
>> reply-type=original
>>
>> HI All
>>
>> I went to Dish Network last week to ask a question and while I was there,
>> asked about some surplus coax. They told me they just dumped a dumpster
>> load that morning, so they are gonna save a bunch for me to pick up
>> tomorrow. Scraps and roll ends, etc. Getting excited about seeing what
>> I'm
>> gonna get for FREE!!
>>
>> Even if it's junk, it will make good radials :-) 73
>> Tom W7WHY
>>
>>
>>>
>>> But, to the average ham with small
>>> antennas and small pockets, it just isn't going to matter.
>>>
>>>
>>> Small antennas and small pockets are not the point. It doesn't take
>>> big
>>> pockets to get that 3 dB, nor does it take big antennas. A little
>>> digging
>>> around for surplus stuff can get you the three dB. Check around for
>>> short
>>> lengths of 7/8 hardline. Many can be had for a fraction of the cost of
>>> 9913. It takes a little searching, but for guys like you with small
>>> pockets,
>>> that 3 dB can be gotten rather cheaply.
>>>
>>> Lots of 75 ohm hardline is available for free for the resourceful guys.
>>> Being on limited budget doesn't mean you have to have a limited signal.
>>>
>>> I am constantly amazed that guys will spend 1K, 2K or more for a radio
>>> and
>>> then cheap out on the coax.
>>>
>>> 73 Bill KH7XS
>>
>>
>>
>> ------------------------------
>>
>> Message: 4
>> Date: Thu, 11 Feb 2010 23:00:52 -0500
>> From: "Roger (K8RI)" <K8RI-on-TowerTalk@tm.net>
>> Subject: Re: [TowerTalk] Measuring Coax Loss
>> To: "Tower and HF antenna construction topics."
>> <towertalk@contesting.com>
>> Message-ID: <4B74D274.6060700@tm.net>
>> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>>
>>
>>
>> Mike Besemer (WM4B) wrote:
>>> I'm aware that when the signal is at the noise floor, it's going to make
>>> a
>>> difference. (Seems like a no-brainer.) But, to the average ham with
>>> small
>>> antennas and small pockets, it just isn't going to matter. Am I the
>>> ONLY
>>> 'average' ham here among a bunch of big guns?
>>>
>> Probably not, but it's highly likely in the minority.
>> But big guns, or little pistols, the overall idea is to do as much as
>> possible with what we have and to share the knowledge as to how we've
>> done it. I'd certainly not call my station a "big gun", but it's most
>> likely not considered mediocre. I've always been an experimenter who
>> tries for the most out of what I have and share how to get there.
>>
>>
>> 73
>>
>> Roger (K8RI)
>>>
>>> -----Original Message-----
>>> From: towertalk-bounces@contesting.com
>>> [mailto:towertalk-bounces@contesting.com] On Behalf Of
>>> Cqtestk4xs@aol.com
>>> Sent: Thursday, February 11, 2010 8:42 PM
>>> To: towertalk@contesting.com
>>> Subject: Re: [TowerTalk] Measuring Coax Loss
>>>
>>>
>>> In a message dated 2/12/2010 1:17:49 AM Greenwich Standard Time,
>>> k5go@cox.net writes:
>>>
>>> 3 dB is very large regardless of how many you are starting with.
>>>
>>>
>>> You bet it is...depending on whose S meter you're looking at it could
>>> be
>>> close to an S unit. Out here when the hordes of EU stations call, many
>>> times they are S-3/4. It doesn't take too many dB to rise above the
>>> pack....like around 3 db. Kinda like a shorty 40 vs a dipole.
>>>
>>> Bill KH7XS
>>> _______________________________________________
>>>
>>>
>>>
>>> _______________________________________________
>>> TowerTalk mailing list
>>> TowerTalk@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/towertalk
>>>
>>> _______________________________________________
>>>
>>>
>>>
>>> _______________________________________________
>>> TowerTalk mailing list
>>> TowerTalk@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/towertalk
>>>
>>>
>>
>>
>> ------------------------------
>>
>> Message: 5
>> Date: Thu, 11 Feb 2010 20:05:31 -0800
>> From: "Mike" <noddy1211@sbcglobal.net>
>> Subject: Re: [TowerTalk] Measuring Coax Loss
>> To: "'Tower and HF antenna construction topics.'"
>> <towertalk@contesting.com>
>> Message-ID: <00c501caab98$9e7be9a0$db73bce0$@net>
>> Content-Type: text/plain; charset="us-ascii"
>>
>> That does not matter, what does is that you can hear the difference
>> between
>> 0db and 3db, that's when a good station shines. Every 3db counts with
>> low
>> signals.
>>
>>
>> Mike
>>
>> -----Original Message-----
>> From: towertalk-bounces@contesting.com
>> [mailto:towertalk-bounces@contesting.com] On Behalf Of Mike Besemer
>> (WM4B)
>> Sent: Thursday, February 11, 2010 5:19 PM
>> To: 'Tower and HF antenna construction topics.'
>> Subject: Re: [TowerTalk] Measuring Coax Loss
>>
>> So... assuming (as someone suggested) that an S-Unit is 3dB... can you
>> hear
>> the difference between S9+40 and S9+41? S9 & S10? S7 & s8?
>>
>>
>>
>> -----Original Message-----
>> From: towertalk-bounces@contesting.com
>> [mailto:towertalk-bounces@contesting.com] On Behalf Of Stan Stockton
>> Sent: Thursday, February 11, 2010 8:17 PM
>> To: Tower and HF antenna construction topics.
>> Subject: Re: [TowerTalk] Measuring Coax Loss
>>
>> dB's.....They are really easy to get in the beginning and become VERY
>> difficult to get once you have about a dozen. They are also extremely
>> addictive. The more of them you have the more of them you want. At
>> some point in time you think about them constantly and buy lotto
>> tickets hoping to win so you can get (please give me!) just three more.
>>
>> 3 dB is very large regardless of how many you are starting with.
>>
>> 73...Stan, K5GO
>>
>> Sent from Stan's IPhone
>>
>> On Feb 11, 2010, at 6:34 PM, "Jim Brown" <jim@audiosystemsgroup.com>
>> wrote:
>>
>>> On Thu, 11 Feb 2010 19:03:51 -0500, Mike Besemer \(WM4B\) wrote:
>>>
>>>> Still... a dB or so (or even 3) on a long run of coax isn't going to
>>>> make a hill of beans difference for most applications... an S-Unit
>>>> is ~ 6dB.
>>>
>>> Only by someone's definition, not in reality. If you actually
>>> MEASURE the
>>> response of the S-meters in REAL radios, you find that an S-unit may
>>> be close
>>> to 6dB near S9, but is usually closer to 3dB at S5 and below.
>>>
>>> As to a hill of beans -- many hams have long runs of coax to their
>>> antennas,
>>> so loss can be a BIG deal, not a hill of beans. The loss in dB of
>>> verious RG8
>>> style coaxes ranges by a factor of about 2:1 from the lowest to the
>>> highest.
>>> Over the past several years, I've been doing a lot of little things to
>>> improve my station. A dB here, a dB there, they all add up. Smart
>>> operators
>>> know that. The difference between a 3-el yagi and a 4-el yagi of
>>> comparable
>>> design is only 1-2 dB, and often double the cost. That doesn't stop
>>> a lot of
>>> guys who have the space from putting up 4-el yagis!
>>>
>>> Somehow, the scientific method seems to be lost on some of those
>>> commenting
>>> on my post. How do you know that the MFJ (or any piece of test gear)
>>> is
>>> accurate if you don't compare it to another measurement or test
>>> method of
>>> known accuracy? I'll bet a six pack of your favorite 807s that if I
>>> had
>>> posted loss measuerements made ONLY with an MFJ, someone would have
>>> pooh-
>>> poohed them because I didn't use equipment traceable to a
>>> calibration lab.
>>>
>>>> Forgot to mention... unless I actually SAW the 10' piece being cut
>>>> off the
>>>> longer roll I was considering buying from, I wouldn't trust the
>>>> measurements
>>>> anyway.
>>>
>>> Did it ever occur to you that sometimes ham stores, even the best
>>> known, with
>>> the biggest ads in QST, may not have good data on what they're
>>> selling? I
>>> don't trust some of them any more than an anonymous vendor in a flea
>>> market.
>>> But there ARE some good deals out there, IF you have an open mind
>>> and know
>>> how to evaluate them. The point of my post was to show that you CAN
>>> get
>>> decent data from an MFJ259B that has been calibrated if you're
>>> measuring a
>>> sample that is long enough.
>>>
>>> How many measurements of coax loas have you actually made? How did
>>> you do it?
>>> How did you know that you had good data? At some point, you've got
>>> to know
>>> exactly how long that piece of coax is. RG8 is big and heavy, so
>>> unspooling
>>> enough of it to get a good measurement isn't always easy. You've got
>>> to deal
>>> with the length of cable sample you can get.
>>>
>>> 73,
>>>
>>> Jim K9YC
>>>
>>>
>>> _______________________________________________
>>>
>>>
>>>
>>> _______________________________________________
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>>> TowerTalk@contesting.com
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>> End of TowerTalk Digest, Vol 86, Issue 45
>> *****************************************
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>
> Regards, Steve
>
>
> Please include all email history in responses until your inquiry or order
> is completed
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