Mike Besemer (WM4B) wrote:
> How, it the real world of ham radio, do you experience hearing the
> difference of 3dB daily?
>
> I'm not talking about a lab.
>
Living here in the snow country, last night on 40 for instance. The
background noise was a very steady S7. It was the kind of steady state
noise where a signal just a little stronger stands out. Were the noise
static crashes, then no, you probably couldn't even tell the difference
with a full S unit, and even a signal 2 S-units stronger on average
might still be difficult copy, but with steady state noise which is very
common during the winter up here, small differences do make the
difference between good copy and no copy, and these are definitely not
weak signals.
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 8:24 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
>>>>
>>>>
>>>> _______________________________________________
>>>>
>>>>
>>>>
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>>>>
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