Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by klubnl.pl (8.14.4/8.14.4/Debian-8+deb8u2) with ESMTP id wB4IdY6n030985 for ; Tue, 4 Dec 2018 19:39:36 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1gUFVh-0007cj-VZ for rs_out_1@blacksheep.org; Tue, 04 Dec 2018 18:33:29 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1gUFVh-0007ca-HS for rsgb_lf_group@blacksheep.org; Tue, 04 Dec 2018 18:33:29 +0000 Received: from smtp2web.tin.it ([212.216.176.236]) by relay1.thorcom.net with esmtp (Exim 4.91_59-0488984) (envelope-from ) id 1gUFVf-0006Z7-7d for rsgb_lf_group@blacksheep.org; Tue, 04 Dec 2018 18:33:28 +0000 Received: from feu13 (10.192.64.23) by smtp2web.tin.it (8.6.060.43) id 5B27C17304600B2B for rsgb_lf_group@blacksheep.org; Tue, 4 Dec 2018 19:33:20 +0100 Received: from (95.249.73.43) by webmailtin.pc.tim.it; Tue, 4 Dec 2018 19:33:20 +0100 Message-ID: <1677a7ef953.marcocadeddu@tin.it> Date: Tue, 4 Dec 2018 19:33:20 +0100 (CET) From: "marcocadeddu@tin.it" To: Mime-Version: 1.0 X-Originating-IP: 95.249.73.43:1210 X-Spam-Score: 0.0 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has NOT identified this incoming email as spam. The original message has been attached to this so you can view it or label similar future email. If you have any questions, see @@CONTACT_ADDRESS@@ for details. Content preview: Hi Paul, aside of my sympathy for how you are managing "the mistery" ;-) just reading this message I had a though.. maybe I'm wrong but after checking a lot of things one more is nothing... I had to inspect my [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [212.216.176.236 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (marcocadeddu[at]tin.it) 0.0 HTML_MESSAGE BODY: HTML included in message X-Scan-Signature: 8d5e679c4ecb21aeba32cebcefaae7cb Subject: R: Re: LF: More on unstable antenna R Content-Type: multipart/alternative; boundary="----=_Part_68625_8195701.1543948400982" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=HTML_MESSAGE autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false ------=_Part_68625_8195701.1543948400982 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Hi Paul, aside of my sympathy for how you are managing "the mistery" ;-) just readin= g this message I had a though.. maybe I'm wrong but after checking a lot of= things one more is nothing... I had to inspect my ATU box (it hosts the LF variometer, the xfmr for LF an= d MF and a couple of vacuum relays for band switching). In one of such insp= ections I seen that my variometer, although uses solid enameled 2mm copper,= generates some heat.. (the top of the box holds signs of the warm up!) so = I assume that when warming the winding can change in shape and spacing.. ma= ybe is not a matter of cm but 1 mm change in diameter or turns spacing can = make some difference in a sharp tuning device. I remember you checked the possible temperature rise of almost all the comp= onents between the TX output and antenna but cannot remember if you checked= the variometer. Keep on Paul! 73, Marco IK1HSS ----Messaggio originale---- Da: paul@n1bug.com Data: 3-dic-2018 18.22 A: Ogg: Re: LF: More on unstable antenna R Hi Rob, I think my reply to Stefan explains what and where I am measuring... until I get a new RF ammeter at least. "Normal" X is zero, as I adjust the variometer (very slightly) at the start of each operating session and don't need to change it during the night unless weather conditions change (precipitation, fog, etc.). "Normal" R does not exist! It varies so widely with season and ambient temperature I wouldn't be able to pick a figure to call normal. At the time of the tests in question, R at the transmitter end of the line varied from 58 ohms at the start of a transmission to 46 ohms 2 minutes later. I calculated that from measured voltage and/or current on a 50 ohm line with no reactance. Translated to the other end of the coax by using 'TLW' software (N6BV) and then multiplied by the transformer impedance ratio, I calculate about 80 ohms dropping to 65 ohms at the antenna / variometer side of the transformer. Believe it or not I have quite a few radials and ground rods in. Good old Maine sand... about as conductive as Teflon! :) 73, Paul On 12/3/18 11:01 AM, Rob Renoud wrote: > Hi Paul, >=20 > Can you provide the values of =E2=80=9Cnormal=E2=80=9D X and R and also w= here and how you are measuring those values?=20 >=20 > 73, > Rob >=20 >> On Dec 3, 2018, at 08:03, DK7FC wrote: >> >> Hi Paul, >> >> How do you measure your antenna current? I know, the scope. But do you m= easure across a small shunt resistor or do you use a current xfmr or someth= ing else? >> >> 73, Stefan >> >> Am 03.12.2018 12:49, schrieb N1BUG: >>> Hi LF, >>> >>> During past days I did some more investigating about that slow >>> antenna R change during Tx. This is making me a little crazy. I >>> don't like RF mysteries! >>> >>> During a 2 minute Tx at 200W, antenna system R reduces about 20% >>> from beginning to end of Tx. >>> >>> During a 2 minute Tx at 100W, antenna system R reduces about 20% >>> from beginning to end of Tx. >>> >>> During a 2 minute Tx at 50W, antenna system R *increases* about 3% >>> from beginning to end of Tx! >>> >>> There is almost no shift in X. >>> >>> I went over everything I could get to (matching xfmr, loading coil, >>> connections between them, etc.) using a IR heat measuring gun. I did >>> not find anything warming up during a long Tx period. It's all cold. >>> >>> I see a similar change happening on MF where I use a completely >>> separate xfmr and loading coil. >>> >>> This may be a clue, but I don't know what it means. I have other >>> antennas around. All those cables come into the basement where there >>> is a disconnect point. All can be disconnected from the short cables >>> which run up into the radio rooms. If I disconnect all other cables >>> at that point, then the LF antenna R change during Tx is about 10%, >>> half what it is usually. The R at the start of a Tx period is the >>> same as always, but it does not decrease as much during the Tx period. >>> >>> I tried connecting the coax shield to the LF antenna ground. That >>> did not make any difference. >>> >>> Just trying to think of possible explanations... >>> >>> Broken or bad connection somewhere up on the top hat of the antenna? >>> Seems something should fall down if so, but it hasn't yet. :) >>> >>> Bad connection in the ground system? All above ground connections >>> are secure. Below ground connections are not accessible in winter >>> but they are heavy solid copper conductors, mostly exothermic welded >>> connections. The one exception is the heavy solid wire which runs >>> from the xfmr secondary down to the underground wire / center ground >>> rod. It is clamped, not welded. But I used three clamps, very tight >>> and with anti-oxidant paste. This connection is just one year old. >>> >>> Ground return currents through some other path which is not stable? >>> I am sure I make RF currents in the power lines, etc. but...??? >>> >>> Does anyone see a clue here? >>> >>> 73, >>> Paul ------=_Part_68625_8195701.1543948400982 Content-Type: text/html;charset="UTF-8" Content-Transfer-Encoding: quoted-printable Hi Paul,

aside of my sympathy for how you are managing "the mistery"= ;-) just reading this message I had a though.. maybe I'm wrong but after c= hecking a lot of things one more is nothing...
I had to inspect my ATU b= ox (it hosts the LF variometer, the xfmr for LF and MF and a couple of vacu= um relays for band switching). In one of such inspections I seen that my va= riometer, although uses solid enameled 2mm copper, generates some heat.. (t= he top of the box holds signs of the warm up!) so I assume that when warmin= g the winding can change in shape and spacing.. maybe is not a matter of cm= but 1 mm change in diameter or turns spacing can make some difference in a= sharp tuning device.

I remember you checked the possible temperatur= e rise of almost all the components between the TX output and antenna but c= annot remember if you checked the variometer.

Keep on Paul!

7= 3, Marco IK1HSS

----Messaggio originale----
Da: paul@n1bug.com
Data: 3-dic-2018 18.22=
A: <rsgb_lf_group@blacksheep.org>
Ogg: Re: LF: More on unstabl= e antenna R

Hi Rob,

I think my reply to Stefan explains what = and where I am measuring...
until I get a new RF ammeter at least.
"Normal" X is zero, as I adjust the variometer (very slightly) at
the = start of each operating session and don't need to change it
during the n= ight unless weather conditions change (precipitation,
fog, etc.).
"Normal" R does not exist! It varies so widely with season and
ambient = temperature I wouldn't be able to pick a figure to call normal.

At t= he time of the tests in question, R at the transmitter end of
the line v= aried from 58 ohms at the start of a transmission to 46
ohms 2 minutes l= ater. I calculated that from measured voltage and/or
current on a 50 ohm= line with no reactance. Translated to the other
end of the coax by usin= g 'TLW' software (N6BV) and then multiplied
by the transformer impedance= ratio, I calculate about 80 ohms
dropping to 65 ohms at the antenna / v= ariometer side of the transformer.

Believe it or not I have quite a = few radials and ground rods in.
Good old Maine sand... about as conducti= ve as Teflon! :)

73,
Paul



On 12/3/18 11:01 AM, Rob= Renoud wrote:
> Hi Paul,
>
> Can you provide the values= of =E2=80=9Cnormal=E2=80=9D X and R and also where and how you are measuri= ng those values?
>
> 73,
> Rob
>
>> On = Dec 3, 2018, at 08:03, DK7FC <selberdenken@posteo.de> wrote:
>&= gt;
>> Hi Paul,
>>
>> How do you measure your an= tenna current? I know, the scope. But do you measure across a small shunt r= esistor or do you use a current xfmr or something else?
>>
>= > 73, Stefan
>>
>> Am 03.12.2018 12:49, schrieb N1BUG:=
>>> Hi LF,
>>>
>>> During past days I = did some more investigating about that slow
>>> antenna R chang= e during Tx. This is making me a little crazy. I
>>> don't like= RF mysteries!
>>>
>>> During a 2 minute Tx at 200W= , antenna system R reduces about 20%
>>> from beginning to end = of Tx.
>>>
>>> During a 2 minute Tx at 100W, antenn= a system R reduces about 20%
>>> from beginning to end of Tx.>>>
>>> During a 2 minute Tx at 50W, antenna system = R *increases* about 3%
>>> from beginning to end of Tx!
>= >>
>>> There is almost no shift in X.
>>>
= >>> I went over everything I could get to (matching xfmr, loading = coil,
>>> connections between them, etc.) using a IR heat measu= ring gun. I did
>>> not find anything warming up during a long = Tx period. It's all cold.
>>>
>>> I see a similar c= hange happening on MF where I use a completely
>>> separate xfm= r and loading coil.
>>>
>>> This may be a clue, but= I don't know what it means. I have other
>>> antennas around. = All those cables come into the basement where there
>>> is a di= sconnect point. All can be disconnected from the short cables
>>&g= t; which run up into the radio rooms. If I disconnect all other cables
&= gt;>> at that point, then the LF antenna R change during Tx is about = 10%,
>>> half what it is usually. The R at the start of a Tx pe= riod is the
>>> same as always, but it does not decrease as muc= h during the Tx period.
>>>
>>> I tried connecting = the coax shield to the LF antenna ground. That
>>> did not make= any difference.
>>>
>>> Just trying to think of po= ssible explanations...
>>>
>>> Broken or bad connec= tion somewhere up on the top hat of the antenna?
>>> Seems some= thing should fall down if so, but it hasn't yet. :)
>>>
>= >> Bad connection in the ground system? All above ground connections<= br>>>> are secure. Below ground connections are not accessible in = winter
>>> but they are heavy solid copper conductors, mostly e= xothermic welded
>>> connections. The one exception is the heav= y solid wire which runs
>>> from the xfmr secondary down to the= underground wire / center ground
>>> rod. It is clamped, not w= elded. But I used three clamps, very tight
>>> and with anti-ox= idant paste. This connection is just one year old.
>>>
>&= gt;> Ground return currents through some other path which is not stable?=
>>> I am sure I make RF currents in the power lines, etc. = ; but...???
>>>
>>> Does anyone see a clue here?>>>
>>> 73,
>>> Paul



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