Return-Path: X-Spam-DCC: paranoid 1181; Body=2 Fuz1=2 Fuz2=2 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, HTML_40_50,HTML_MESSAGE autolearn=no version=3.1.3 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id t9FCfwGc012702 for ; Thu, 15 Oct 2015 14:41:59 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1ZmhnA-0000iU-F0 for rs_out_1@blacksheep.org; Thu, 15 Oct 2015 13:37:56 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Zmhn9-0000iL-Sa for rsgb_lf_group@blacksheep.org; Thu, 15 Oct 2015 13:37:55 +0100 Received: from vms173017pub.verizon.net ([206.46.173.17]) by relay1.thorcom.net with esmtps (TLSv1:DHE-RSA-AES256-SHA:256) (Exim 4.86) (envelope-from ) id 1Zmhm6-0002PJ-Tg for rsgb_lf_group@blacksheep.org; Thu, 15 Oct 2015 13:37:54 +0100 Received: from MichaelSappPC ([108.32.76.2]) by vms173017.mailsrvcs.net (Oracle Communications Messaging Server 7.0.5.32.0 64bit (built Jul 16 2014)) with ESMTPA id <0NW900CO8HOBKG40@vms173017.mailsrvcs.net> for rsgb_lf_group@blacksheep.org; Thu, 15 Oct 2015 07:36:16 -0500 (CDT) X-CMAE-Score: 0 X-CMAE-Analysis: v=2.1 cv=WpDWSorv c=1 sm=1 tr=0 a=jOWw+/LgadJuWH+9QOwlJg==:117 a=o1OHuDzbAAAA:8 a=oR5dmqMzAAAA:8 a=5lJygRwiOn0A:10 a=r77TgQKjGQsHNAKrUKIA:9 a=JEUDJotMAAAA:8 a=F3M5lZpKAAAA:8 a=tCRDd5CxL_ctYbw6bHsA:9 a=pzCxrAemtAgSwUFr:21 a=4RZzkvk8pS3pb6ia:21 a=wPNLvfGTeEIA:10 a=69EAbJreAAAA:8 a=50mUQrhvlsPHwm5fHCYA:9 a=bG6MUwNCCGhH_zOD:21 a=11wsLBAhBHil7bJ3:21 a=p6ficY21Ks0ihGHh:21 a=_W_S_7VecoQA:10 Message-id: From: "Michael Sapp" To: References: <1821006912.20151014193718@chriswilson.tv> In-reply-to: Date: Thu, 15 Oct 2015 08:36:04 -0400 MIME-version: 1.0 X-Priority: 3 X-MSMail-priority: Normal X-Mailer: Microsoft Windows Mail 6.0.6002.18197 X-MIMEOLE: Produced By Microsoft MimeOLE V6.0.6002.18463 X-Scan-Signature: 6ae4eec5875a1b41a36d2a35c03bf59e Subject: Re: LF: PA0RDT antenna near a TX? Front end OK? Content-type: multipart/alternative; boundary="----=_NextPart_000_000E_01D10724.87B63F20" 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 X-Scanned-By: MIMEDefang 2.56 on 10.1.3.10 Status: O X-Status: X-Keywords: X-UID: 4392 This is a multi-part message in MIME format. ------=_NextPart_000_000E_01D10724.87B63F20 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Laurence & All: It would be interesting to take one of those Array = Solutions Receiver Front End Protectors http://arraysolutions.eestage.com/as-rxfep and replace the pair of isolation transformers in it with something that = is optimized for 100kHz to 1MHz service. The above-mentioned product is = rated for use down to 500 kHz, but I would be concerned about the IMD = performance of those transformers in normal service and the nearby AM = broadcast band signal levels.... I have been thinking of ordering one of these units for placement after = my LF converter, as I run a +23dBm LO and DBM (Level 23 RAY6 from Mini Circuits). If a mixer diode fails, my IF = receiver would see + 23dBm at 3.000 MHz. I built a version of W1VDs 500kHz variable high-Q preselector that covers 3.2 to 3.5 MHz, = which offers some protection to my IF receiver, but the saturated 1:1 transformer seems like a more elegant solution.... Not all receivers have push-pull 2N5109 front ends. The kind of power = levels discussed are a potential overload-damage hazard, especially = outside the the LF/MF frequency range. I have an FT-847 with a dead = preamp stage from accidently leaving the radio connected to my 2M yagi = with my 144.3 CW beacon running 20 feet away. 10mw on the rx input = killed it.... The TS-2000 is known to be worse for rx overload damage = at VHF/UHF. Some of the HEMT devices used for preamps have -10 dBm = danger zones and will likely expire at levels above 0dBM.....so it is = worthwhile to determine the safe operating limits of a receiver's front = end active device..... 73, Mike wa3tts ----- Original Message -----=20 From: Laurence KL7 L=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Thursday, October 15, 2015 1:26 AM Subject: Re: LF: PA0RDT antenna near a TX? Front end OK? Chris Mike JNT et al - So this piqued my measurement interest=20 This evening running circa 2W ERP at 137kHz 1Kw from Decca 5501, I = measured the following:- Ve7sl clone 10ft diameter screened mag loop burhans amp at 50ft from = 500ft circumference tx loop gave plus 13.2dBm into terminated 75ohms W = and G SPM30 (oerrr!) - this is normally connected via a 6dB pad to an = Icom R75 without issue to date. Amp appears to have a lot of "head room" And -8.4dBm from an LF engineering L400b probe at 150ft or so Interesting Laurence KL7L WE2XPQ Wspr 2 136kHz till dawn On Oct 14, 2015, at 12:27, Michael Sapp wrote: Laurence, Chris & All: I did a test with my eprobe which is about = 30 feet away from my HF elevated ground plane that has 65 ft radials a = few years back. With 100W output on 40 meters. I was getting 1mw of RF = power from the eprobe into a Boonton RF voltmeter. I was using a 1 inch = wide by 12 inch long brass strip as the eprobe antenna at the time. I = would assume the eprobe may be able to generate more power than that at = higher nearby transmitter power levels. Suitable overload protection for = a receiver front end would appear to be prudent..... 73, Mike wa3tts ----- Original Message -----=20 From: Laurence KL7 L=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Wednesday, October 14, 2015 2:56 PM Subject: RE: LF: PA0RDT antenna near a TX? Front end OK? Chris =20 I run up to 1Kw on 136kHz and up to 400W on 475kHz and "alive" = Eprobes (L400 and PA0RDT variants) about 100-150ft away up at 30ft plus = and not blown them up. They don't like it much of course and produce = unwanted products during Tx but that not surprising. =20 Only FET failure to date has been down in Oklahoma from a nearby = lightning strike. =20 =20 Laurence KL7L et al =20 > >=20 > If I mount my PA0RDT clone on my mast stub, about 50 feet from = my LF > TX'ing aerial, is it likely to be damaged if powered on when = TX'ing? >=20 > Thanks. > Best regards, > Chris mailto:chris@chriswilson.tv >=20 >=20 ------=_NextPart_000_000E_01D10724.87B63F20 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Laurence & All:  It would be = interesting=20 to take one of those Array Solutions Receiver Front End = Protectors
 
http://arraysolutions= .eestage.com/as-rxfep
 
and replace the pair of isolation = transformers in=20 it with something that is optimized for 100kHz to 1MHz service. The=20 above-mentioned product is rated for use down to 500 kHz, but I would be = concerned about the IMD performance of those transformers in normal = service and=20 the nearby AM broadcast band signal levels....
 
I have been thinking of ordering one of = these units=20 for placement after my LF converter, as I run a +23dBm LO and = DBM
 
(Level 23 RAY6 from Mini = Circuits).  If a=20 mixer diode fails, my IF receiver would see + 23dBm at 3.000 MHz.  = I built=20 a version
 
of W1VDs 500kHz variable high-Q = preselector=20 that covers 3.2 to 3.5 MHz, which offers some protection to my = IF=20 receiver, but the
 
saturated 1:1 transformer seems = like a more=20 elegant solution....
 
Not all receivers have push-pull 2N5109 = front ends.=20 The kind of power levels discussed are a potential overload-damage = hazard,=20 especially outside the the LF/MF frequency range.  I have an FT-847 = with a=20 dead preamp stage from accidently leaving the radio connected to my 2M = yagi with=20 my 144.3 CW beacon running 20 feet away. 10mw on the rx input killed=20 it....  The TS-2000 is known to be worse for rx overload damage at = VHF/UHF.=20 Some of the HEMT devices used for preamps have -10 dBm danger zones and = will=20 likely expire at levels above 0dBM.....so it is worthwhile to determine = the safe=20 operating limits of a receiver's front end active = device.....
 
73, Mike wa3tts
----- Original Message -----
From:=20 Laurence KL7 L =
Sent: Thursday, October 15, = 2015 1:26=20 AM
Subject: Re: LF: PA0RDT antenna = near a=20 TX? Front end OK?

Chris Mike JNT et al - So this piqued my measurement = interest 

This evening running circa 2W ERP at 137kHz 1Kw from Decca 5501, = I=20 measured the following:-

Ve7sl clone 10ft diameter screened mag loop burhans amp at 50ft = from=20 500ft circumference tx loop gave plus 13.2dBm  into terminated = 75ohms W=20 and G SPM30 (oerrr!) - this is normally connected via a 6dB pad to an = Icom R75=20 without issue to date.
Amp appears to have a lot of "head room"

And -8.4dBm from an LF engineering L400b probe at 150ft or = so

Interesting

Laurence KL7L WE2XPQ
Wspr 2 136kHz till dawn



On Oct 14, 2015, at 12:27, Michael Sapp <wa3tts@verizon.net>=20 wrote:

Laurence, Chris & All:  I = did a test=20 with my eprobe which is about 30 feet away from my HF elevated = ground plane=20 that has 65 ft radials a few years back. With 100W output on 40 = meters. I=20 was getting 1mw of RF power from the eprobe into a Boonton RF = voltmeter. I=20 was using a 1 inch wide by 12 inch long brass strip as the = eprobe=20 antenna at the time.  I would assume the eprobe may be able to = generate=20 more power than that at higher nearby transmitter power=20 levels. Suitable overload protection for a receiver front end = would=20 appear to be prudent.....
 
73, Mike wa3tts
 
 
----- Original Message ----- =
From:=20 Laurence KL7 L =
To: rsgb_lf_group@blacksheep.org= =20
Sent: Wednesday, October = 14, 2015=20 2:56 PM
Subject: RE: LF: PA0RDT = antenna near=20 a TX? Front end OK?

Chris
 
I run up to 1Kw on 136kHz = and up to=20 400W on 475kHz and "alive" Eprobes (L400 and PA0RDT = variants)=20 about 100-150ft away up at 30ft plus and not blown them up. = They=20 don't like it much of course and produce unwanted products during = Tx but=20 that not surprising.
 
Only FET failure to date has = been down=20 in Oklahoma from a nearby lightning=20 strike.
 
 
Laurence
KL7L et = al
 
>
>
> If I mount my PA0RDT clone on my mast = stub,=20 about 50 feet from my LF
> TX'ing aerial, is it likely to be = damaged=20 if powered on when TX'ing?
>
> Thanks.

> = Best=20 regards,
> Chris mailto:chris@chriswilson.tv
&= gt;=20
>=20
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