Re: Topband: fixing beverage

[Mike Waters]

It would be a simple matter to use my old Tektronix 465B scope as a TDR.

But I'd love to have a good dual-port VNA. :-)

73, Mike
www.w0btu.com

On Tue, Nov 24, 2015 at 3:18 PM, Jim Brown 
wrote:

> There are multiple ways to do TDR. I like the way that this unit does it
> -- an inverse FFT of a frequency sweep.
>
> http://sdr-kits.net/VNWA3_Description.html
>
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Re: Topband: fixing beverage

[Jim Brown]

On Tue,11/24/2015 1:30 PM, Mike Waters wrote:

But I'd love to have a good dual-port VNA.:-)


See the price - about $700 with cal kit and shipping.

73, Jim K9YC
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Re: Topband: fixing beverage

[Jim Brown]

On Mon,11/23/2015 2:06 PM, Mike Waters wrote:

Maybe things have improved lately, but AIM would not be my first choice.


There are multiple ways to do TDR. I like the way that this unit does it 
-- an inverse FFT of a frequency sweep.


http://sdr-kits.net/VNWA3_Description.html

To expose small perturbations in the feedline or system, make the sweep 
at VHF/UHF. To see only the more gross defects, sweep from about 50-150 
MHz. To understand this, remember that a linear frequency sweep will 
spend more time in the high octaves than the low ones, so the greatest 
contribution to the display will be that higher octave, whatever you 
have chosen.


In the example posed by the question about varmint damage, I'd set it 
for 200 - 1,000 MHz to see small nicks in the braid, 50 - 150 MHz to see 
the connectors and splices.


73, Jim K9YC


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Re: Topband: fixing beverage

[Tom W8JI]

I've been doing FFT-based measurements since 1982.  I suggest that you try 
a technique before you criticize it. Your analysis is badly mistaken.


Jim,

Factually, the little bumps or even big bumps on VHF are meaningless for 
active problems on lower frequencies.   They might predict a future issue, 
but on 160 meters even crushing a cable flat for five feet would be 
meaningless for receive loss unless the center actually contacted the 
shield.


This is just the way things work, and it is important we get our heads 
around the way things work.


If I wanted to find the reason for high signal loss on 160, the last thing I 
would ever do is look at the system on 150 MHz or even 30 MHz.   I would 
first look at the system down around where the problem is, or as close as I 
could to that frequency.


I can go out and slice half of the shield off for 10 feet and not tell a 
difference in receive 160 signal, but it would be terrible on VHF. VHF 
certainly tells us a future problem or a defect nicely, but it will not 
directly point reliably to the LF issue unless by chance there is only one 
bad spot.


I use a TDR when applicable, and that is about once every three or four 
years. I can find and fix any cable system for HF with a cheap common SWR 
analyzer, and so can anyone else. I can sit in my house and find a bad 
connection 1000 feet away by sweeping the SWR between 1.8 and 5 MHz, and get 
within a foot, and not spend $500 on equipment.


73 Tom 


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Re: Topband: fixing beverage

[Jim Brown]

On Tue,11/24/2015 3:02 PM, Tom W8JI wrote:
Actually, to see the more gross defects, we would look at a lower 
frequency. I don't want to imagine what my 160 stuff would look like 
at VHF.


Tom,

I've been doing FFT-based measurements since 1982.  I suggest that you 
try a technique before you criticize it. Your analysis is badly mistaken.


73, Jim K9YC

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Re: Topband: fixing beverage

[Jim Brown]

On Tue,11/24/2015 5:56 PM, Tom W8JI wrote:
Factually, the little bumps or even big bumps on VHF are meaningless 
for active problems on lower frequencies.   They might predict a 
future issue, but on 160 meters even crushing a cable flat for five 
feet would be meaningless for receive loss unless the center actually 
contacted the shield.


Factually, that is not good analysis. One can use any measurement tool 
in multiple ways. If, for example, one is searching for tiny holes the 
outer diectric that are letting in water, we must look at the higher 
frequencies to see that level of detail. We're not looking for SWR or 
loss, we're looking for some sort of mechanical defect that degrades the 
cable.


On Tue,11/24/2015 5:56 PM, Tom W8JI wrote:
If I wanted to find the reason for high signal loss on 160, the last 
thing I would ever do is look at the system on 150 MHz or even 30 
MHz.   I would first look at the system down around where the problem 
is, or as close as I could to that frequency. 


That's because you don't understand FFT analysis. I'm not looking for 
the loss, I'm looking for the CAUSE of the loss, and I want to get 
within a few inches of it. You CANNOT do that with a low frequency test 
signal -- the system does not have sufficient resolution.


73, Jim K9YC
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Topband: CE3CT on 160 this weekend

[Tree]

Hello,

Wanted to pass along a brief piece of info…  I will be active from CE3CT as
SOAB during CQWW.   Will be active on 80/160 for those needing CE on those
bands (especially 160m).  There is currently very little interest in
serious low-band DX’ing from CE, so I don’t think it is terribly common.
(I could be wrong & CE is the most common place in the world)

I will be QRV the 2nd night — Saturday night and QRX for NA/EU.  Usually CE
contesters get on, work LU, a PY, another CE and get back to business but I
will try to make an effort to work as many as reasonable.  Hope this is of
interest to the TB community.

73, Jason CE3/N5NU
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Re: Topband: fixing beverage

[Tom W8JI]

There are multiple ways to do TDR. I like the way that this unit does 
it -- an inverse FFT of a frequency sweep.


http://sdr-kits.net/VNWA3_Description.html

To expose small perturbations in the feedline or system, make the sweep at 
VHF/UHF. To see only the more gross defects, sweep from about 50-150 MHz. 
To understand this, remember that a linear frequency sweep will spend more 
time in the high octaves than the low ones, so the greatest contribution 
to the display will be that higher octave, whatever you have chosen.


Actually, to see the more gross defects, we would look at a lower frequency. 
I don't want to imagine what my 160 stuff would look like at VHF.   :)


A system can have a  500 ohm transmission impedance bump 1 foot long on 160 
meters and it just doesn't matter. The general rule is if a reasonable 
impedance discontinuity is less than one degree long, it will not upset the 
system. SO 239's, for example, are about 35 ohms in the female's joining 
spring part (the males are nearly perfect). The effect of that bump is 
nearly immeasurable below 100 MHz.


We all know a one foot long chunk of wire that might be 400-800 ohms surge 
impedance barely changes SWR and adds immeasureable loss between the coax 
and a vertical base on 160. Same reason. Although the wire is a "major" 
impedance bump, it is electrically not too long.


What we cannot tolerate on 160 are resistive series connections and low 
resistance shorts shunting the system, or cross coupling from sharing common 
currents.


On 160 meters, if we simply measure RF voltage across the input of a line 
while sweeping low frequency, recording the repeating frequency of voltage 
minimums, we can find the distance to any cable or connection problem 
affecting the system by more than a few dB. Little lumps and bumps at VHF 
might locate a future issue like a chewed shield, but for an existing signal 
loss they are just a distraction.


If a shield develops high resistance 800 feet from my house, the high series 
resistance will cause a repeating voltage null 800/492 = 1.626 MHz apart.


If I swept the line and saw repeating nulls spaced 3 MHz apart, I would know 
an issue existed 492 / 3=164 electrical feet away.  If the cable was .85 vf 
, the issue would be 164*.85 = 139.4 feet away physically. This would be 
true for an open or a short.


All the software and refinement does for locating major existing issues 
affecting level is eliminate the use of a calculator. Any SWR measuring 
device, or even a simple voltage indicator, could do the job.   I can find a 
bump affecting receive levels with a Heathkit VF1 VFO and a 1N34 diode and 
meter about as well as I can with a TDR on 160.:) 


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Re: Topband: fixing beverage

[Jorge Diez CX6VM]

Thanks all for the help, will upgrade software and try to use it as TDR

73,
Jorge


Enviado desde mi iPhone

> El 23 nov. 2015, a las 23:00, Bill Hider  escribió:
> 
> Jorge,
> 
> I have used my AIM4170 many times as a TDR.  Your 3 year old AIM_853.exe 
> should work, but it is free & easy go upgrade to the latest (October 26, 
> 2015) software revision, AIM_910B.
> 
> Download AIM_910B here:
> 
> WWW.w5big.com/prog_update.htm
> 
> Bill N3RR
> 
>> On Nov 23, 2015 8:03 PM, donov...@starpower.net wrote:
>> 
>> Hi Jorge, 
>> 
>> The AIM4170 has TDR capabilities. I don't own an AIM470, but 
>> surely someone on the Topband reflector can help you use it 
>> as a TDR. 
>> 
>> 73 
>> Frank 
>> W3LPL
>> 
>> - Original Message -
>> 
>> From: "Jorge Diez - CX6VM"  
>> To: donov...@starpower.net 
>> Sent: Monday, November 23, 2015 11:56:32 PM 
>> Subject: RE: Topband: fixing beverage
>> 
>> Hi Frank
>> 
>> I google and the first option was Campbellsci.es
>> 
>> In 5 minutes the CX representative emailed me and told me that is a very 
>> very expensive toy for my use :-)
>> 
>> I have the AIM4170, will do this job? I use the software AIM_852.exe I need 
>> another software or this is OK?
>> 
>> Thanks, 
>> Jorge 
>> 
>> -Mensaje original- 
>> De: Topband [mailto:topband-boun...@contesting.com] En nombre de 
>> donov...@starpower.net 
>> Enviado el: lunes, 23 de noviembre de 2015 06:51 p.m. 
>> Para: topband@contesting.com 
>> CC: dl8yhrfr...@aol.com 
>> Asunto: Re: Topband: fixing beverage 
>> 
>> Hi Frank, 
>> 
>> My TDR is nearly fifty years old, but still it works great. 
>> 
>> Array Solutions sells more modern multi-functions devices that are perform 
>> very well as a TDR. Here's an example display from Array Solutions' web 
>> site: 
>> 
>> https://www.arraysolutions.com/images/AIMuhf-TDR-fig1.png 
>> 
>> The display for a Beverage looks very similar, you can see every component 
>> from the shack to the termination resistor. 
>> 
>> 73 
>> Frank 
>> W3LPL 
>> 
>> - Original Message -
>> 
>> From: dl8yhrfr...@aol.com 
>> To: donov...@starpower.net 
>> Sent: Monday, November 23, 2015 9:20:55 PM 
>> Subject: Re: Topband: fixing beverage
>> 
>> where can i get such toy? 
>> 
>> 
>> 
>> 
>> -Urspr ngliche Mitteilung- 
>> Von: donovanf  
>> An: TopBand List  
>> Cc: Jorge Diez - CX6VM  
>> Verschickt: Mo, 23 Nov 2015 9:39 pm 
>> Betreff: Re: Topband: fixing beverage 
>> 
>> 
>> 
>> A Time Domain Reflectometer is one of the best tools to verify 
>> the proper performance and isolate faults of a Beverage and many 
>> other types of antennas. 
>> 
>> In the case of a Beverage, the TDR allows you to see every 
>> component of the antenna system from the ham shack all the way 
>> to the termination resistor. If anything fails you can almost 
>> always walk directly to it with the needed replacement parts and 
>> tools in hand. 
>> 
>> 73 
>> Frank 
>> W3LPL
>> 
>> - Original Message -
>> 
>> From: "Jorge Diez - CX6VM" < cx6vm.jo...@gmail.com > 
>> To: "TopBand List" < topband@contesting.com > 
>> Sent: Monday, November 23, 2015 8:29:15 PM 
>> Subject: Re: Topband: fixing beverage
>> 
>> Thanks all you guys for the help
>> 
>> Will do this tests and see what is wrong
>> 
>> 73, 
>> Jorge 
>> CX6VM/CW5W
>> 
>> -Mensaje original- 
>> De: Tom W8JI [ mailto:w...@w8ji.com ] 
>> Enviado el: lunes, 23 de noviembre de 2015 02:35 p.m. 
>> Para: Jorge Diez - CX6VM; 'TopBand List' 
>> Asunto: Re: Topband: fixing beverage
>> 
>>> 
>>> I notice that my USA beverage is lower in 3-4 S units that some weeks ago.
>> 
>> 5-20 dB. Depending on receiver and where it is at on the S meter.
>> 
>> That has to be a poor connection, open, or short between the receiver and 
>> the 
>> Beverage transformer end of the Beverage. It cannot be at the termination 
>> end. 
>> 
>>> At simple view all seems to be OK. I think the coax is not the 
>>> problem, because if I have a problem in the coax, will be completely deaf,
>> right?
>> 
>> No. Coax can do this. It happens all the time. Especially at connectors.
>> 
>>> 
>>> So this can be the cause of a problem in the end resistor or maybe in 
>>> the transformer? I use in this beverage a WX0B beverage boxes
>> 
>> It can not be at the end resistor termination.
>> 
>> The problem is if you disturb something it will often start working. You 
>> need to 
>> carefully check one thing at a time. Many times, if not most times, this is 
>> corrosion or tarnish on the center pin of the coax. Sometimes it is a broken 
>> wire, or a bad part from lightning or water.
>> 
>> The best way to test it is with an SWR meter and do a frequency sweep from 
>> the 
>> house, before you touch the antenna or any outside connections. The 
>> frequency of 
>> either adjacent major dips in SWR or impedance will allow you to calculate 
>> exactly where the problem is. The 

Re: Topband: fixing beverage

[Tom Homewood]

I agree with Mike, check the ground connection at the Beverage feed point.

73 Tom W1TO

On 11/23/2015 10:26 AM, Mike Waters wrote:

Not necessarily.

I've seen a poor ground cause low signal levels.

73, Mike
www.w0btu.com

On Mon, Nov 23, 2015 at 8:21 AM, Jorge Diez - CX6VM 
wrote:


... I think the coax is not the problem, because if I have a problem in
the coax, will be completely deaf, right?


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Topband: Fwd: fixing beverage

[K1FZ-Bruce]

We have had a lot of recent posting about animal damage lately. Always a 
possibility. 
 
Your TDR should help provide resolution to the problem where ever, what ever it 
is. 
Was a good suggestion from W3LPL
 
73
Bruce-k1fz
www.qsl.net/k1fz/bogantennanotes.html
 
 

On Tue, 24 Nov 2015 06:32:47 -0300, Jorge Diez CX6VM  wrote:

  Thanks all for the help, will upgrade software and try to use it as TDR

73,
Jorge

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Topband: A QRP "test" this evening

[James Rodenkirch]

>From 0200Z to 0330Z tomorrow, this evening here in the U.S., some of us 
>participants in a weekly QRP Fox hunt will be experimenting in a Top Band 
>version centered around 1.810.


Keeping it brief, our Fox "hunts" consist of two or more Fox stations operating 
somewhere within a 20 kHz spread of 20 meters (once a week during the summer) 
and 40 and 80 (twice a week during the winter). The main objective of the 
"hunts" is to collect data on who was worked where, at what RST reports so that 
participants can observe/learn about the affects of propagation.


We have Tuesday evenings off this week and next so we opted to try 160 and see 
how well some of the participants can do on Top Band; we assume, since we'll be 
down at the low end of the band and operating at QRP levels, we won't "bother 
anybody." The Fox station calls CQ Fox and the other participants, the Hounds, 
exchange a report consisting of RST, State, Name and PWR level.


If you hear anyone calling CQ Fox OR hear someone sending the exchange, listen 
in, figure out who's the "calling CQ party" and have a mind to "help out," take 
a moment to work us!! Operating at 5 watts or less is "mo betta" BUT, even a 
call at higher power will be appreciated.


HEY - it's winter, WX sucks and us QRP aficionados are easily amused.72 de 
Jim Rodenkirch K9JWV

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