Return to KLUBNL.PL main page

[Top] [All Lists]

Re: LF: TX > RX isolation test

To: [email protected]
Subject: Re: LF: TX > RX isolation test
From: N1BUG <[email protected]>
Date: Thu, 19 Jul 2018 08:42:11 -0400
Autocrypt: addr=[email protected]; prefer-encrypt=mutual; keydata= xsFNBFqj1+0BEACggWlaH8oG/AiXSUG3CeQwZ1NrVEP4U7YsA9N9XEffjCDEsnTjHF2BJSgS 2AicyomkmTGvghEHxrNFfFw07jwgJl97ae/VtNxpERPSE98mb4sPOMpJbwddioMazMDXwhKA wpg5fse+Ru8OrIT04KK919xL/pZuAP6pY6d2kVoizjJOfS71pHpiU6N6q3d9cl+w7d2LKhAE a3A1ZgDquPvn0WQlrN8K5D66xVrwTRhf1b5H4Ozl8/mMJzCeLG1ZIsDB3Pu2flwE81P8dCJA y1azwgY8pTEshVk4em/se9uRiZaDJr/qUSCf6hrV7AGa8g1jpAQDmdGpDNYMqyDqXen4jNi1 8kNFVu1BMl2vjaI8skw/YPxIxlk/0ROHYhN6SuoDq1mt4AW4FryNa7k3A8dM8Bt7udBoTv0i uw4j9R/bmh2vl/QaHRUhDco0xn2z6geWvXkKqha++vzXDrEKUuqgB85SDZPs5W/phs9p0pz1 xA61d1gn8FQJtpou5dQuAucqMo8eKQY5LUcbC+MH5pebH+M2wIuDCBmFPJHQDSPNepeaxJ4o G/HU1hrpzlgLiTTSKR8DcwtMQwYywnCTlm8MgL4jXuPzoGyKDMYyKIjC51G+3AAOJ6oXJAGR g0ehhCPtmnCGBaRlUIoUSpbgc4B+onqFKZmDiVm9CRNJhKIWrQARAQABzRZOMUJVRyA8cGF1 bEBuMWJ1Zy5jb20+wsF9BBMBCAAnBQJao9ftAhsjBQkJZgGABQsJCAcCBhUICQoLAgQWAgMB Ah4BAheAAAoJECRS/J8srRGjPBsQAIh+Haz9gqrQJ0OlMI5xmQ0A5nsVWcatWF/Ea4mucNjL 4n4jmW+Z4Ukn3OVss55chWwrOVMRNWU2d2zRc92ZF7yJhLCoJFV870bZfxNYwdJ3GEBLIu6/ anmQYX0oXFx8UBsx5K6egNqbeflPA7zrLiQkWrz6JApECdiA1rHDjyJdS7PDxBCG9cKgr/5b r4Rn/JlUl9pRPnxlSwHXsV+J6JtFYtWI69MWIVD7Y7OY1wO9+684uOnzeDANzeIwpBDcSm6p 0D5u0b1hfPl2TD0ozVs6P0NvxkMbimXUhRR1QD0FvydyxmZTLAo+XZDGR8GqWYrYrauoRZ1h 3m23+bNT2T4AuoFnWekpsZu+sxIf0LKPtEZCa51O65jZ810ROpXg9Lx71gEoQD+kbjO69+kq 9r7wjytDq/jyhpOGrGYV6kgcQrISY86t9YvkA9Of2HDzZLih3GwecW6fkeV1AO5w4RteE9nL zIs2siGw2YqavF6LpTH71Db7cUYyZWn5hkKpwfpLNnPEuqgZACovpH1WUHx+KMqqIL4rMVCH GcSLqnH2KF4cEDb6OeTbwuLfpGlN+I3j24eQnB2uz5rDa7/IBjsClLl8S/wdDTP8IikBGixX 06v3k06tk/OF4UsfJ0cY/ASGP5+kjT4ASMZAIikwVMpKi5A5be77vecKNYlJQ2a6zsFNBFqj 1+0BEACaujZXo3F17v7QTnub4DjjYvm+nr8J0uU5pPc1UMEz9eWjmtmITm15fx1hPKNtVW+I VlT+DG+ShNnYmO2M4CFBoc7PwkAOc70aDxfHz20kotvj1HhXG7oBiqPkN3TK4C7qWV1HUEPA V960qPdhsoCqmtkvNwj39w1T0ZR5qwwaqDogs9UwBib7zseQ3OXHG32xYYCMcxM35hgXGkkz R7wFL4ZnAPOeFb8LnWtZcrGpwXdsYkXuCxm+A+u9KlFY+w3ZCzZt1F9Ie+/PSZnFIUtbXt2i mfc+VkRwOLz5BDAeWuDL09TN81+gbrR3kXlymDcCbuduO/yHOQK085qzE3LuImdy+JNb7oDf 1C/hvpRvtB02vVy33rzIXT8644SJzFY/mw/W39/BgHKCoL1FrBbfgf0UoIFw5M752i7jQwmv j5yFfnVAXIPpCuusMwWMGVpZcGV7QxJxh0HBEhYgOo9v3zKwzNIPm9V/LA67u/rj4a/MlCE0 mpd6IHaePE1vXDaboPZHZdhAziru5/Jd7KQI0k+HmM/HRANPRNDZ4UeBpgj9PzS6hDN5GHlZ fRUbI8JAg9wSaQtEn0bjyaR7lw0yngZTvvjT1Qqt5zGwm1IAall2STes5xK0aS7p+UJJMVbf ydZ5VOnocvUkwYxbiqoyuVtGxi4tpWW9CRstYXMkAwARAQABwsFlBBgBCAAPBQJao9ftAhsM BQkJZgGAAAoJECRS/J8srRGjTDMP/18q7uhac/naxoFsOqhgXIlvaPgu6GX7s/QOh+bcSV1F y50lxo51P/C95H2TVME/CtCjk2xWQcNjWtXloMEsZpl7T3qWgJHvyZYkDtgh3M6UNY+zb08U K9E2+rR0AZ6zdMKio7Z1xA9BtbUpSZpvy2NgjoYVqo35NllUWMZJq0u+88PvE5WeCIqLipNI EZmUcG9UwolQbPkrRc42ReL+bFbuXGXDA5GbQ0RudXbugI8iUwaw3ftaKElIZtuHW0hw1VrU 9tVHsxKyEoKgNNT1hr+dgRmvCHmA87Pi4R5cMV0ZkLVOYfPX1motedag7HmSNPi2PkYLts4z kyvPEJe2IvaPvjvK1ShRWWgje3uytrhfwyjUZcIuA76RWEfBbwT2Mbrn9O7LvrYtbTiTlsLo Zdk2uocuefBvPd2oI7mTn5eLy/VDy2JVnlb9vpZZhriXI4KtCcP6mYyuPxlxqj/30Kn1fU5b C4EpnKy6hW1CHM42DbwzT+ChjBpFbX9bfwT4qn6d42+T4mN5wkmfnBRHfcn8Wf1ezRSK3Ome Esa3ZDssj23CZHe11uec6Ln14qoB7JyRT9qM3Q99tzvAlmWFM3GrSsG94g4JponQjQWHmr8B eMYezwJHzSI7zWElJpzs/OuohstTYfYTy16FygUOEinc1K4ywjEklgRpXRtjKvqc
In-reply-to: <[email protected]>
Openpgp: preference=signencrypt
References: <[email protected]> <[email protected]om> <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]>
Reply-to: [email protected]
Sender: [email protected]
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1
Hi Stefan,

On 07/19/2018 03:55 AM, DK7FC wrote:
> Well i don't feel like a real expert too.

>From my perspective you are a real expert! I have learned much from
you. I am grateful for your kindness and patience explaining things
to me.

> But here i would say that the 
> equivalent circuit is a constant voltage source (the TX antenna while 
> transmitting) coupled to the RX system. The coupling element is the 
> capacity between the wires and it will be in the sub-pF range.

OK. Understood.

>> Ah. I see. In fact I have no idea what complex impedance it presents.
> I would expect is is less than 1 Ohm due to the extreme winding ratio of 
> your transformer, if you actually have 100 turns primary and 1 turn on 
> the preamp side.

Oh, sorry, I created a misunderstanding. I meant 100:1 impedance. It
is 80 turns on the antenna side, 8 turns on the feedline side.

> That is a good idea. Instead of a 9m long wire you can try a much 
> shorter wire but at a higher height above the ground. This can lead to 
> better results and it will lower the coupling capacity to the TX antenna.
> Just search in the web for the PA0RDT mini whip to get some ideas for 
> the schematic design. A 0.3m long wire is quite fine for LF and MF, as 
> long as it is at the highest point, above all trees. The effective 
> height is essential.

Well, this is why I used the 9m long whip instead of a mini-whip or
similar. I have many trees to 25m height. There is only one way to
get above them, that is to put the mini-whip at the top of either
tower, eg. at 37m height. But both towers are connected to the TX
antenna ground system so there would no ground isolation.

Speaking of trees, I am a bit surprised my TX antenna is working
like it is. There is a small open space around it, but then many
trees around 3 sides of this small clear area. Along one side the
forest is not more than 6 or 7m from the vertical wire. But my half
power WSPR-2 signal was copied in G, PA, and DL. I guess this is not
too bad. There will be no more half power transmitting for me. When
I return the signal will be a little better. :-)

> No problem!
> But can't you use a big battery and a solar module instead of power over 
> coax? Then you can use a (or 2) transformer to decouple the grounds 
> between the house and the RX site. Would be a pity if you bring the 
> noise from the house over to the RX site via the coax! Just experiment 
> by using a battery in the first tests. I would use 2 1:1 transformers to 
> decouple the grounds of the sites.

I like the isolation idea of course. I am very well aware of common
mode issues! I have been at war with them a few times. Assuming I
find some type of antenna which is happy near the trees, then I have
some challenge to locate it where a solar panel can get sun.

Certainly solar power is possible. Whether it is possible this year
depends on the size of the panel / battery, which I have to think
about. I took the decision to delay replacing the roof on my house
for one more year so I could get the LF TX to full power and make
one new RX antenna in 2018. But even so, the budget has hard limits.

> A loop is even easier i find. And it is very quickly done. And the trees 
> will give useful supports, they don't lower the RX signal much (at 
> LF/MF). You just need some wire, a capacitor, a small ferrite core. 
> That's all! With that you can build a resonated loop with a 50 Ohm 
> output to feed your existing preamp. I would even recommend to start 
> with this project first! You will be surprised! Done in 1 day. And you 
> can transmit on that antenna with say 5W (when using good capacitors 
> such as WIMA FKP-1).

Hmm, I don't think we are meaning the same thing when we say loop. I
was thinking something like this:

but I think you have a simpler design in mind. Can you point me to a
link for more information? I probably have everything needed to make

Paul N1BUG

<Prev in Thread] Current Thread [Next in Thread>