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 wB6Ed0tI010233 for ; Thu, 6 Dec 2018 15:39:01 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1gUug0-0004qQ-AX for rs_out_1@blacksheep.org; Thu, 06 Dec 2018 14:30:52 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1gUufz-0004qG-QA for rsgb_lf_group@blacksheep.org; Thu, 06 Dec 2018 14:30:51 +0000 Received: from smtp3web.tin.it ([212.216.176.237]) by relay1.thorcom.net with esmtp (Exim 4.91_59-0488984) (envelope-from ) id 1gUuft-0003oX-OR for rsgb_lf_group@blacksheep.org; Thu, 06 Dec 2018 14:30:50 +0000 Received: from feu12 (10.192.64.22) by smtp3web.tin.it (8.6.060.43) id 5B6DEBA202FA2756 for rsgb_lf_group@blacksheep.org; Thu, 6 Dec 2018 15:30:44 +0100 Received: from (95.249.73.43) by webmailtin.pc.tim.it; Thu, 6 Dec 2018 15:30:44 +0100 Message-ID: <16783ed944e.marcocadeddu@tin.it> Date: Thu, 6 Dec 2018 15:30:44 +0100 (CET) From: "marcocadeddu@tin.it" To: Mime-Version: 1.0 X-Originating-IP: 95.249.73.43:1362 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, yes, I do agree: dimensional change in the variometer should drive to changes both in reactance and resistance and if you have the variometer included in the loading coil you had already checked it. S [...] 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 [212.216.176.237 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: 8784cdbd504ef8804d6bf58c55c77386 Subject: R: Re: R: Re: LF: More on unstable antenna R Content-Type: multipart/alternative; boundary="----=_Part_67517_248304.1544106644561" 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_67517_248304.1544106644561 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Hi Paul, yes, I do agree: dimensional change in the variometer should drive to chang= es both in reactance and resistance and if you have the variometer included= in the loading coil you had already checked it. Sorry this was not the culprit.. I guess that your thought about a (faulty or semi-faulty) ground connection= at this point should be the better candidate but not easy to check (specia= lly if the bad point is not close to the antenna feed point but elsewhere). Bad insulation in the high part of the antenna will give problems but mainl= y arching so in this case you can see rapid changes in DC and RF currents w= hen arch is active.. (already experienced.. ) You need some luck when you can check the ground connections and find a laz= y connection without have to rebuild the full ground system.. probably you = have to wait for springtime to access properly the ground system but we sta= y tuned ;-) 73, Marco IK1HSS ----Messaggio originale---- Da: paul@n1bug.com Data: 5-dic-2018 22.02 A: Ogg: Re: R: Re: LF: More on unstable antenna R Hi Marco, I just got a new IR heat sensing device. It could not see any warming of the transformer or loading coil (variometer). If the loading coil changed from heat, I would expect to see it mostly in change of resonant frequency, not a change in resistance as I am seeing? I think I must have some connection in the ground which changes resistance with RF current flowing, but it's very strange. 73, Paul On 12/4/18 1:33 PM, marcocadeddu@tin.it wrote: > Hi Paul, >=20 > 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 ATU box (it hosts the LF variometer, the xfmr for LF > and MF and a couple of vacuum relays for band switching). In one > of such inspections 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.. 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. >=20 > I remember you checked the possible temperature rise of almost > all the components between the TX output and antenna but cannot > remember if you checked the variometer. >=20 > Keep on Paul! >=20 > 73, Marco IK1HSS >=20 >=20 >=20 > ----Messaggio originale---- Da: paul@n1bug.com Data: 3-dic-2018 > 18.22 A: Ogg: Re: LF: More on > unstable antenna R >=20 > Hi Rob, >=20 > I think my reply to Stefan explains what and where I am > measuring... until I get a new RF ammeter at least. >=20 > "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.). >=20 > "Normal" R does not exist! It varies so widely with season and=20 > ambient temperature I wouldn't be able to pick a figure to call > normal. >=20 > 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. >=20 > Believe it or not I have quite a few radials and ground rods in.=20 > Good old Maine sand... about as conductive as Teflon! :) >=20 > 73, Paul >=20 >=20 >=20 > 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 = where >> and how you are measuring those values? >>=20 >> 73, Rob >>=20 >>> On Dec 3, 2018, at 08:03, DK7FC >>> wrote: >>>=20 >>> Hi Paul, >>>=20 >>> How do you measure your antenna current? I know, the scope. >>> But do you measure across a small shunt resistor or do you >>> use a current xfmr or something else? >>>=20 >>> 73, Stefan >>>=20 >>> Am 03.12.2018 12:49, schrieb N1BUG: >>>> Hi LF, >>>>=20 >>>> 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! >>>>=20 >>>> During a 2 minute Tx at 200W, antenna system R reduces >>>> about 20% from beginning to end of Tx. >>>>=20 >>>> During a 2 minute Tx at 100W, antenna system R reduces >>>> about 20% from beginning to end of Tx. >>>>=20 >>>> During a 2 minute Tx at 50W, antenna system R *increases* >>>> about 3% from beginning to end of Tx! >>>>=20 >>>> There is almost no shift in X. >>>>=20 >>>> 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. >>>>=20 >>>> I see a similar change happening on MF where I use a >>>> completely separate xfmr and loading coil. >>>>=20 >>>> 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. >>>>=20 >>>> I tried connecting the coax shield to the LF antenna >>>> ground. That did not make any difference. >>>>=20 >>>> Just trying to think of possible explanations... >>>>=20 >>>> 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. :) >>>>=20 >>>> 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. >>>>=20 >>>> Ground return currents through some other path which is not >>>> stable? I am sure I make RF currents in the power lines, >>>> etc. but...??? >>>>=20 >>>> Does anyone see a clue here? >>>>=20 >>>> 73, Paul >=20 >=20 >=20 >=20 >=20 --=20 Paul N1BUG 2200m-2m DXCC Honor Roll FN55mf ME Piscataquis County http://www.n1bug.com http://www.aurorasentry.com ------=_Part_67517_248304.1544106644561 Content-Type: text/html;charset="UTF-8" Content-Transfer-Encoding: quoted-printable Hi Paul,

yes, I do agree: dimensional change in the variometer shoul= d drive to changes both in reactance and resistance and if you have the var= iometer included in the loading coil you had already checked it.
Sorry t= his was not the culprit..

I guess that your thought about a (faulty = or semi-faulty) ground connection at this point should be the better candid= ate but not easy to check (specially if the bad point is not close to the a= ntenna feed point but elsewhere).

Bad insulation in the high part of= the antenna will give problems but mainly arching so in this case you can = see rapid changes in DC and RF currents when arch is active.. (already expe= rienced.. )

You need some luck when you can check the ground connect= ions and find a lazy connection without have to rebuild the full ground sys= tem.. probably you have to wait for springtime to access properly the groun= d system but we stay tuned ;-)

73, Marco IK1HSS

----Messaggio originale----
Da: paul@n1bug.com
Data: 5-dic-2018 22.02=
A: <rsgb_lf_group@blacksheep.org>
Ogg: Re: R: Re: LF: More on = unstable antenna R

Hi Marco,

I just got a new IR heat sensing= device. It could not see any
warming of the transformer or loading coil= (variometer). If the
loading coil changed from heat, I would expect to = see it mostly in
change of resonant frequency, not a change in resistanc= e as I am seeing?

I think I must have some connection in the ground = which changes
resistance with RF current flowing, but it's very strange.=

73,
Paul


On 12/4/18 1:33 PM, marcocadeddu@tin.it wrot= e:
> Hi Paul,
>
> aside of my sympathy for how you are m= anaging "the mistery" ;-)
> just reading this message I had a though.= . maybe I'm wrong but
> after checking a lot of things one more is no= thing... I had to
> inspect my ATU box (it hosts the LF variometer, t= he xfmr for LF
> and MF and a couple of vacuum relays for band switch= ing). In one
> of such inspections I seen that my variometer, althoug= h 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.. maybe is not a
&g= t; matter of cm but 1 mm change in diameter or turns spacing can
> ma= ke some difference in a sharp tuning device.
>
> I remember yo= u checked the possible temperature rise of almost
> all the component= s between the TX output and antenna but cannot
> remember if you chec= ked the variometer.
>
> Keep on Paul!
>
> 73, Mar= co IK1HSS
>
>
>
> ----Messaggio originale---- Da= : paul@n1bug.com Data: 3-dic-2018
> 18.22 A: <rsgb_lf_group@blacks= heep.org> Ogg: Re: LF: More on
> unstable antenna R
>
&g= t; Hi Rob,
>
> I think my reply to Stefan explains what and wh= ere 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
&= gt; it during the night unless weather conditions change
> (precipita= tion, fog, etc.).
>
> "Normal" R does not exist! It varies so = widely with season and
> ambient temperature I wouldn't be able to p= ick a figure to call
> normal.
>
> At the time of the te= sts in question, R at the transmitter end
> of the line varied from 5= 8 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 l= ine with no reactance. Translated to
> the other end of the coax by u= sing 'TLW' software (N6BV) and then
> multiplied by the transformer i= mpedance ratio, I calculate about
> 80 ohms dropping to 65 ohms at th= e antenna / variometer side of
> the transformer.
>
> Be= lieve it or not I have quite a few radials and ground rods in.
> Goo= d old Maine sand... about as conductive as Teflon! :)
>
> 73, = Paul
>
>
>
> On 12/3/18 11:01 AM, Rob Renoud wro= te:
>> Hi Paul,
>>
>> Can you provide the value= s of =E2=80=9Cnormal=E2=80=9D X and R and also where
>> and how yo= u are measuring those values?
>>
>> 73, Rob
>> =
>>> On Dec 3, 2018, at 08:03, DK7FC <selberdenken@posteo.de= >
>>> wrote:
>>>
>>> Hi Paul,
&g= t;>>
>>> How do you measure your antenna current? I know= , the scope.
>>> But do you measure across a small shunt resist= or or do you
>>> use a current xfmr or something else?
>&= gt;>
>>> 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 m= e 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.
&g= t;>>>
>>>> During a 2 minute Tx at 100W, antenna s= ystem R reduces
>>>> about 20% from beginning to end of Tx.<= br>>>>>
>>>> During a 2 minute Tx at 50W, anten= na 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 betwe= en 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 cl= ue, but I don't know what it means. I have
>>>> other antenn= as around. All those cables come into the
>>>> basement wher= e 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 wh= at it is usually. The R at the start of a Tx
>>>> period is = the same as always, but it does not decrease as
>>>> much du= ring the Tx period.
>>>>
>>>> I tried connec= ting the coax shield to the LF antenna
>>>> ground. That did= not make any difference.
>>>>
>>>> Just try= ing to think of possible explanations...
>>>>
>>&g= t;> Broken or bad connection somewhere up on the top hat of the
>&= gt;>> antenna? Seems something should fall down if so, but it
>= >>> hasn't yet. :)
>>>>
>>>> Bad co= nnection in the ground system? All above ground
>>>> connect= ions are secure. Below ground connections are not
>>>> acces= sible in winter but they are heavy solid copper
>>>> conduct= ors, mostly exothermic welded connections. The one
>>>> exce= ption 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
>>&g= t;> tight and with anti-oxidant paste. This connection is just
>&g= t;>> one year old.
>>>>
>>>> Ground re= turn currents through some other path which is not
>>>> stab= le? I am sure I make RF currents in the power lines,
>>>> et= c.  but...???
>>>>
>>>> Does anyone see= a clue here?
>>>>
>>>> 73, Paul
> >
>
>
>

--
Paul
N1BUG  2200m-2= m        DXCC Honor Roll
FN55mf =      ME      Piscataquis Count= y
http://www.n1bug.com
http://www.aurorasentry.com



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