Re: Topband: 75 ohm RG6 to 50 Ohm radio

[Tree]

One easy thing you can do to test your transformer is to put a 75 ohm
resistor on the proper side - and then use an SWR meter to measure the
impedance on the 50 ohm side.  I like to also see how high in frequency I
can go before the SWR starts to rise.  Most of the transformers I wind
typically work pretty well up to 7 or 10 MHz.

If you don't have an SWR meter - you can use your transmitter set for a
power level that won't burn up your resistor.

Tree N6TR

On Wed, Sep 28, 2016 at 10:58 AM, Ed Stallman  wrote:

> Thanks all for your wisdom . Some say not needed and some say to use the
> 75 / 50 transformer . I figure it's easy enuf to do . So now I'll try it
> and see for my self .
>
> Thanks again, Ed N5DG
>
>
> On 9/27/2016 10:35 PM, Ed Stallman wrote:
>
>> My receive antenna is 75 Ohm RG6 connected to my radio and I want to wind
>> a 2873000202 binocular core to step 75 to 50 Ohm's . I seen this info on
>> W8JI web page but can't seem to find it again.
>>
>> I do remember it's 4 turns 50 Ohm and 5 turns 75 Ohm and all wires come
>> out the same side of the core . Am I correct so far?
>>
>> Does it make a difference which winding I wind first ?
>>
>> Thanks in advance , Ed N5DG
>>
>>
>>
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Re: Topband: 75 ohm RG6 to 50 Ohm radio

[Ed Stallman]

Thanks all for your wisdom . Some say not needed and some say to use the 
75 / 50 transformer . I figure it's easy enuf to do . So now I'll try it 
and see for my self .


Thanks again, Ed N5DG


On 9/27/2016 10:35 PM, Ed Stallman wrote:
My receive antenna is 75 Ohm RG6 connected to my radio and I want to 
wind a 2873000202 binocular core to step 75 to 50 Ohm's . I seen this 
info on W8JI web page but can't seem to find it again.


I do remember it's 4 turns 50 Ohm and 5 turns 75 Ohm and all wires 
come out the same side of the core . Am I correct so far?


Does it make a difference which winding I wind first ?

Thanks in advance , Ed N5DG



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Re: Topband: YC0LOW SK

[Greg - ZL3IX]

Very sad news, indeed. When I first became interested in 160m as ZS5K 
back in 1997, Jo was my first ever contact on the band. He put a 
cracking signal into Durban.


Condolences to Jo's family.

73, Greg ZL3IX (ex ZS5K)

On 2016-09-29 05:02 a.m., Preston Smith wrote:

Very sad news, following from Joz, YD1JZ.
Pres/N6SS

-Original Message-
From: yd1jz@gmail.com
Sent: Wed, 28 Sep 2016 22:22:26 +0700
To: n...@inbox.com
Subject: YC0LOW SK

Hello OM Pres,

Hope you are doing fine.

Would like to inform that our dear friend OM Jo - YC0LOW has passed away this 
afternoon in Jakarta at 10:30 hrs UTC.

Please kindly inform as well this sad news to Top Banders community as 
Indonesia amateur radio is really missing one of our good brother who indeed 
have dedicated his life in 160 M.

Thanks for your assistance.

Best 73

Joz YD1JZ


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Topband: 75 ohm RG6 to 50 Ohm radio

[Lee STRAHAN]

Actually there is a reason or two to match the feedline impedances when 
using these active antennas.
There are amplifiers in most of these systems that rely on their matched 
impedances to produce their best IMD capability. It may not matter in some 
areas of the world but in others with high levels of broadcast signals it 
definitely could. This of course is also dependent on the length of 
transmission line which can make the mismatch worse or even better under 
certain circumstances. Then if the mismatch is made better on one band due to 
mismatch it likely won't be on another band. One other reason that matching 
matters is the impedance a mismatched line loads the combining circuitry can 
under some circumstances cause phase and amplitude errors. This can change the 
originally intended pattern of an array. In the case of the Hi-Z arrays they 
all are supplied with an amplifier that has a 75 ohm input impedance so the 
array controllers stay accurate in terms of phase and amplitude. However this 
amplifier like most post amplifiers partially reflects its output load changes 
back to
  its input changing the input impedance. Thus the reason for the 75 to 50 ohm 
transformer as it keeps the amplifier happy.
  Now this may or may not affect some users but as a manufacturer of these 
arrays it is important to insure that these arrays will work well and do it at 
every install around the world. We have seen feedlines as short as 3 feet up to 
the 1000 foot runs I use and one that I heard of at 2000 feet.
So my point is why would one want to possibly give away some performance 
when it could very easily be done correctly.
  One caveat is that the Hi-Z 4 and 4-8Pro have an internal buffer amplifier 
designed specially to eliminate the amplitude and phasing problems arising from 
load mismatch but it cannot maintain its IMD capability under some incorrect 
load conditions. Other models do not include this internal buffering of the 
output signal.
Lee   K7TJR  OR


>I suppose I need to ask if worrying about impedance at this point in the
> system is really worth the trouble.
>
> Once signals have gone through one or two stages of amplification - would
> a
> loss of a db or so in signal strength really matter?
>

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Topband: YC0LOW SK

[Preston Smith]

Very sad news, following from Joz, YD1JZ.
Pres/N6SS

-Original Message-
From: yd1jz@gmail.com
Sent: Wed, 28 Sep 2016 22:22:26 +0700
To: n...@inbox.com
Subject: YC0LOW SK

Hello OM Pres,

Hope you are doing fine. 

Would like to inform that our dear friend OM Jo - YC0LOW has passed away this 
afternoon in Jakarta at 10:30 hrs UTC. 

Please kindly inform as well this sad news to Top Banders community as 
Indonesia amateur radio is really missing one of our good brother who indeed 
have dedicated his life in 160 M. 

Thanks for your assistance. 

Best 73

Joz YD1JZ


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Re: Topband: 75 ohm RG6 to 50 Ohm radio

[Chortek, Robert L.]

To Tree's point:  have the Hi-Z Triangular Array and use it with the 75/50 
transformer.

After using it for a year or so, and just for curiosity sake I pulled out the 
transformer and hooked the 75 ohm cable directly to the receiver input.  I went 
back and forth multiple times and my ears never noticed a difference.  Not a 
scientific test to be sure, but

73,

Bob AA6VB

Sent from my iPhone

On Sep 28, 2016, at 7:48 AM, Tree > wrote:

I suppose I need to ask if worrying about impedance at this point in the
system is really worth the trouble.

Once signals have gone through one or two stages of amplification - would a
loss of a db or so in signal strength really matter?

Tree N6TR

On Tue, Sep 27, 2016 at 8:46 PM, Lee STRAHAN 
> wrote:


Yes Ed, You have the right numbers. It won't matter which windings are
first or last. You can even wind 4 then wind 1 more and use it as an
autotransformer where the 1 turn is added to the 4 for 5. Any of these will
work fine at these TOP Band and higher frequencies. This ratio is not
perfect but will work just fine. It would be 50 to 78 ohms which in our
world is close enough.
Let us know how your new 8 circle works. Maybe even compare it to your
Hi-Z 4-square.
Lee   K7TJR

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Ed
Stallman
Sent: Tuesday, September 27, 2016 8:35 PM
To: topband@contesting.com
Subject: Topband: 75 ohm RG6 to 50 Ohm radio

My receive antenna is 75 Ohm RG6 connected to my radio and I want to wind
a 2873000202 binocular core to step 75 to 50 Ohm's . I seen this info on
W8JI web page but can't seem to find it again.

I do remember it's 4 turns 50 Ohm and 5 turns 75 Ohm and all wires come
out the same side of the core . Am I correct so far?

Does it make a difference which winding I wind first ?

Thanks in advance , Ed N5DG



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Re: Topband: 75 ohm RG6 to 50 Ohm radio

[Tree]

I suppose I need to ask if worrying about impedance at this point in the
system is really worth the trouble.

Once signals have gone through one or two stages of amplification - would a
loss of a db or so in signal strength really matter?

Tree N6TR

On Tue, Sep 27, 2016 at 8:46 PM, Lee STRAHAN  wrote:

>
>  Yes Ed, You have the right numbers. It won't matter which windings are
> first or last. You can even wind 4 then wind 1 more and use it as an
> autotransformer where the 1 turn is added to the 4 for 5. Any of these will
> work fine at these TOP Band and higher frequencies. This ratio is not
> perfect but will work just fine. It would be 50 to 78 ohms which in our
> world is close enough.
>  Let us know how your new 8 circle works. Maybe even compare it to your
> Hi-Z 4-square.
> Lee   K7TJR
>
> -Original Message-
> From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Ed
> Stallman
> Sent: Tuesday, September 27, 2016 8:35 PM
> To: topband@contesting.com
> Subject: Topband: 75 ohm RG6 to 50 Ohm radio
>
> My receive antenna is 75 Ohm RG6 connected to my radio and I want to wind
> a 2873000202 binocular core to step 75 to 50 Ohm's . I seen this info on
> W8JI web page but can't seem to find it again.
>
> I do remember it's 4 turns 50 Ohm and 5 turns 75 Ohm and all wires come
> out the same side of the core . Am I correct so far?
>
> Does it make a difference which winding I wind first ?
>
> Thanks in advance , Ed N5DG
>
>
>
> ---
> This email has been checked for viruses by Avast antivirus software.
> https://www.avast.com/antivirus
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Re: Topband: 75 ohm RG6 to 50 Ohm radio

[Grant Saviers]

One thing that W8JI clarified for me in winding binocular cores is what 
is a "turn".  Normally, a wire thru a toroid hole is a "turn". A 
binocular core is two toroids in a single piece of ferrite.  Tom 
proposed calling a wire in one side of a binocular core a "pass" and 
thru both sides a "turn".  Thus, 2.5 "turns" are possible with 5 
"passes".  Usually, a "turn" by authors means 2 "passes" but there are 
exceptions.


With the different windings coming out of opposite ends there will be a 
little less stray coupling and it makes it easier to connect them to 
their respective connectors. If there is no ground path between the 
conductors then you have an isolation transformer which can reduce noise 
pickup.


I use small watertight plastic boxes I found on ebay for all sorts of 
receive antenna projects, very well made.

http://www.ebay.com/itm/Clear-Waterproof-Cover-Plastic-Electronic-Project-Box-Enclosure-CASE-85x58x33mm/201653764558?_trksid=p2047675.c15.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D39007%26meid%3D1c6a2a52ecb446888faad4eadfecbe82%26pid%3D15%26rk%3D3%26rkt%3D18%26sd%3D262605424625

If you use some 30ga insulated wire wrap wire, it is less fragile 
against the ferrite and has a higher isolation voltage between the 
windings than enamel insulation.  A little RTV or hot melt keeps the 
core secured to the box.


Grant KZ1W

On 9/27/2016 20:46 PM, Lee STRAHAN wrote:

  Yes Ed, You have the right numbers. It won't matter which windings are first 
or last. You can even wind 4 then wind 1 more and use it as an autotransformer 
where the 1 turn is added to the 4 for 5. Any of these will work fine at these 
TOP Band and higher frequencies. This ratio is not perfect but will work just 
fine. It would be 50 to 78 ohms which in our world is close enough.
  Let us know how your new 8 circle works. Maybe even compare it to your Hi-Z 
4-square.
Lee   K7TJR

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Ed Stallman
Sent: Tuesday, September 27, 2016 8:35 PM
To: topband@contesting.com
Subject: Topband: 75 ohm RG6 to 50 Ohm radio

My receive antenna is 75 Ohm RG6 connected to my radio and I want to wind a 
2873000202 binocular core to step 75 to 50 Ohm's . I seen this info on W8JI web 
page but can't seem to find it again.

I do remember it's 4 turns 50 Ohm and 5 turns 75 Ohm and all wires come out the 
same side of the core . Am I correct so far?

Does it make a difference which winding I wind first ?

Thanks in advance , Ed N5DG



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