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 w6F0819Q023769 for ; Sun, 15 Jul 2018 02:08:03 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1feUNA-0006OU-Um for rs_out_1@blacksheep.org; Sun, 15 Jul 2018 00:54:44 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1feUN8-0006OL-CL for rsgb_lf_group@blacksheep.org; Sun, 15 Jul 2018 00:54:42 +0100 Received: from resqmta-ch2-12v.sys.comcast.net ([2001:558:fe21:29:69:252:207:44]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.91_59-0488984) (envelope-from ) id 1feUN5-0003HQ-3g for rsgb_lf_group@blacksheep.org; Sun, 15 Jul 2018 00:54:41 +0100 Received: from resomta-ch2-19v.sys.comcast.net ([69.252.207.115]) by resqmta-ch2-12v.sys.comcast.net with ESMTP id eUIQfVLCL6OTpeUMzfgR5U; Sat, 14 Jul 2018 23:54:33 +0000 X-DKIM-Result: Domain=comcast.net Result=Signature OK DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=comcast.net; s=q20161114; t=1531612473; bh=5lH5NgTkVtGzJ5N7uIHfyPyBTksCXNBmtO8tpTSRj8Y=; h=Received:Received:From:Subject:To:Content-Type:MIME-Version:Date: Message-ID; b=o0BuQlBfFabKMUig2go651gUp3hlCMD0PzTd+WKXgS0qus+yOhWC8d2vct6MOpOAr w92qfVictGZtkC4NFU2upptaU5fTHdQYIIlGEgcJ3EjnFoG1G7mFrBQlBaA632G6fx rtc7vrEhUScWPhmlNnDCgtsYOP9QJXzQ/VYOl+fllVOASpzgajFSoGEbp39cBsaEJY /o5OiO8UubjcOSKuqNW+DPK7zGrVX0e94QrgPozE/DfcDQbzjFaQlyPOIynGXDGQOw xUlUhjpWdtkYmZS7jXyStWIuQfydgwCbFtAO8ut2QvyNTnNcvk/wq9Xk75wb2eurjZ XWT2J6BJCG1pg== Received: from Optiplex980-PC ([73.4.253.141]) by resomta-ch2-19v.sys.comcast.net with ESMTPA id eUMxfm4t4UQxBeUMxfMeYz; Sat, 14 Jul 2018 23:54:33 +0000 From: "jrusgrove@comcast.net" To: "rsgb_lf_group@blacksheep.org" MIME-Version: 1.0 References: <50f24ef2-2d1d-b537-7d66-e6d12ecf8cc3@n1bug.com> <8e720108-88eb-11a7-4f41-ef67c7ae74c9@n1bug.com> <1UQWeI91kE.7cbTRbTeCVJ@optiplex980-pc> Date: Sat, 14 Jul 2018 19:54:30 -0400 Message-ID: <1UQWn0FzVr.1HxCa9v5tM0@optiplex980-pc> In-Reply-To: User-Agent: OEClassic/2.9 (Win7.7601; P; 2018-07-03) X-CMAE-Envelope: MS4wfHb8lxG7h1gKU2ogBNTeWdqSycg8wOIZEmE8Cni3MTuJFjSX8NrVjSS1NG2lRDo4NaIKIpCmxUyHJ3iGckb1BnMA9uPAajvDZaTx8ZQWytij10HhjAdd TRNaNs4lMhSc7Vxs25N3kbeDBsw96fR1sW+rmMAXqUQTbEoR+grjzigywFJeqBJOLOliLpSudwz1fg== X-Spam-Score: -0.7 (/) 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: Andy Maybe I can shed further light on my comments ... The ARRL receiver measurement system was developed by Wes Hayward of Tektronics back in the mid 70's and has been used with minor changes since. Instead of calculating 3IP the system quotes third order IMD dynamic range relative to the noise floor (MDS - minimum descernable signal). The MDS is deemed as the signal level at which a 3 dB increase over 'background' noise is noted - as measured by an audio voltmeter. The measurement is normally made with the receiver in a cw bandwidth and is quoted in dBm. QST quotes the MDS for the this transverter as -125 dBm. For the two-tone IMD dynamic range measurement, two tones (at selected spacings) are injected into the receiver and the level is increased until the third order products are 3 dB above the background noise - at the MDS level. The two-tone dynamic range is the difference between MDS and the signal generator level. [...] Content analysis details: (-0.7 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at http://www.dnswl.org/, low trust [2001:558:fe21:29:69:252:207:44 listed in] [list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (jrusgrove[at]comcast.net) -0.0 SPF_PASS SPF: sender matches SPF record -0.0 T_RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 0.0 HTML_MESSAGE BODY: HTML included in message 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: 783e848a630124d13ae6ef06c152f951 Subject: Re: LF: RE: Simple transverter for 472kHz Content-Type: multipart/alternative; boundary="GjF3Ncb12ueMkjNr2dpcCV7ID=_G6IpMKN" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.5 required=5.0 tests=HTML_20_30,HTML_MESSAGE, TO_ADDRESS_EQ_REAL 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 This is a multi-part message in MIME format --GjF3Ncb12ueMkjNr2dpcCV7ID=_G6IpMKN Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Andy Maybe I can shed further light on my comments ...=20 The ARRL receiver measurement system was developed by Wes Hayward of T= ektronics=20 back in the mid=20 70's and has been used with minor changes since. Instead of calculatin= g 3IP the system quotes third order IMD dynamic range relative to the = noise floor (MDS - minimum descernable signal). The MDS is deemed as t= he signal level at which a 3 dB increase over 'background' noise is no= ted - as measured by an audio voltmeter. The measurement is normally = made with the receiver in a cw bandwidth and is quoted in dBm. QST quo= tes the MDS for the this transverter as -125 dBm. For the two-tone IMD= dynamic range measurement, two tones (at selected spacings) are injec= ted into the receiver and the level is increased until the third order= products are 3 dB above the background noise - at the MDS level. The = two-tone dynamic range is the difference between MDS and the signal ge= nerator level.=20 For this transverter with a -125 dBm MDS and 60 dB dynamic range at 2 = kHz tone spacing, the indicated signal level to cause third order IMD = products would be -65 dBm. At 75 kHz spacing the signal level would be= -51 dBm. Calculating IP3 for 2 kHz spacing using -125 dBm and -65 dBm= produces an IP3 of -35 dBm. Calculating IP3 for 75 kHz spacing using = -125 dBm and -51 dBm produces an IP3 of -14 dBm.=20 I normally think in dynamic range numbers, not IP3, since I've=20 been using the 'Hayward system' since the beginning. Since you think i= n IP3=20 numbers how do those=20 IP3's look to you? Jay W1VD WD2XNS WE2XGR/2 =20 ----- Original Message ----- From: Andy Talbot Reply-To: To: LineOne Sent: 7/14/2018 7:38:16 AM Subject: Re: LF: RE: Simple transverter for 472kHz Those IMD figures don't=20 in themselves say enough to say whether it is good or bad. Firstly, that quoted paragraph=20 doesn't give the input levels at which IMPs were 60 [75dB] down. It = is more usual to give a third order intercept point (TOIP)when specif= iying linearity; a figure quoted in dBm Secondly, specifying IMPs at different bandwidths is meaningless too, = as there is no indication of the receiver filtering. So all in all, rejecting that receive converter based on that quoted p= aragraph is going too far. If a level-7 (+7dBm Local Oscillator) diode ring mixer were to be used= at the front end, with no preceding preamp and minimal loss filtering= , you might reasonably expect a TOIP in the +15 to +20dBm region. T= hat means IM Products will be, (in dB below theinput) twice the amount= the RF input is below the TOIP. An example : TOIP =3D +20dBm Two tone input at a level of -20dBm IMPS =3D +20dBm - 2 * (+20dBm - -20dBm =3D -60dBc on the input si= gnals. Or equivalent to -80dBm So two -20dBm signal into a typical 7dBm LO diode ring mixer give -60d= Bc third order products. A diode ring is what any self respecting designer might use on a basic= LF receiver converter A level 13 mixer (+13dBm) wpouild give a proprtionately higher TOIP, p= erhaps +25 to +30dBm For higher linearity / better strong signal handling still, a bus-swi= tch mixer offers a TOIP perhaps +35 to +45dBm. Like the Softrock rec= eivers Andy www.g4jnt.com On 14 July 2018 at 12:13, N1BUG wrote: Ouch! Having operated on 160m and the HF bands for several years using a receiver that comes in at about -63 dB on 2 kHz spacing third-order IMD I would never again buy something with that kind of receiver "performance". Paul N1BUG On 07/06/2018 09:45 PM, jrusgrove@comcast.net wrote: > Saw the writeup in QST and immediately noticed the receive > two-tone, third-order IMD at 2 kHz spacing is 60 dB and at 75 kHz > spacing is only 74 dB! Good luck with that if you've=20 got strong > signals at your location. >=20 > Jay W1VD WD2XNS WE2XGR/2 --GjF3Ncb12ueMkjNr2dpcCV7ID=_G6IpMKN Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline
Andy
 
Maybe I can shed further light on my comments ... 
 
The ARRL receiver measurement system was developed by Wes Ha= yward of Tektronics back in the mid 70's and has been used w= ith minor changes since. Instead of calculating 3IP the syst= em quotes third order IMD dynamic range relative to the noise floor (M= DS - minimum descernable signal). The MDS is deemed as the s= ignal level at which a 3 dB increase over 'background' noise = ;is noted - as measured by an audio voltmeter.  The measurem= ent is normally made with the receiver in a cw bandwidth and is quoted= in dBm. QST quotes the MDS for the this transverter as -125 dBm.= For the two-tone IMD dynamic range measurement, two tones (at se= lected spacings) are injected into the receiver and the level is = increased until the third order products are 3 dB above the backg= round noise - at the MDS level. The two-tone dynamic range i= s the difference between MDS and the signal generator level.
 
For this transverter with a -125 dBm MDS and 60 dB dynamic range = at 2 kHz tone spacing, the indicated signal level to cause third order= IMD products would be -65 dBm. At 75 kHz spacing the signal leve= l would be -51 dBm. Calculating IP3 for 2 kHz spacing using -125 = dBm and -65 dBm produces an IP3 of -35 dBm. Calculating IP3 for 7= 5 kHz spacing using -125 dBm and -51 dBm produces an IP3 of = -14 dBm.
 
I normally think in dynamic range numbers, not IP3, sin= ce I've been using the 'Hayward system' since the beginning. Sinc= e you think in IP3 numbers how do those IP3's look to you?
 
Jay W1VD  WD2XNS  WE2XGR/2     = ; 
 
 
----- Original Message -----
From: Andy Talbot <andy.g4jnt@gmail.com>
Sent: 7/14/2018 7:38:16 AM
Subject: Re: LF: RE: Simple transverter for 472kHz
Those IMD figures don't in themselves say enough to say= whether it is good or bad.

Firstly, that quoted paragraph doesn't give the input levels at w= hich IMPs were 60 [75dB] down.   It is more usual to give a = third order intercept point  (TOIP)when specifiying linearity; a = figure quoted in dBm

Secondly, specifying IMPs at different bandwidths is meaningless = too, as there is no indication of the receiver filtering.

So all in all, rejecting that receive converter based on that quo= ted paragraph is going too far.

If a level-7 (+7dBm Local Oscillator) diode ring mixer were to be= used at the front end, with no preceding preamp and minimal loss filt= ering, you might reasonably expect a TOIP in the +15 to  +20dBm r= egion.   That means IM Products will be, (in dB below theinp= ut) twice the amount the RF input is below the TOIP.  An example = :

TOIP =3D +20dBm
Two tone input at a level of -20dBm
IMPS   =3D    +20dBm - 2 * (+20dBm - -20dBm =3D= -60dBc on the input signals.  Or equivalent to -80dBm

So two -20dBm signal into a typical 7dBm LO diode ring mixer give= -60dBc third order products.
A diode ring is what any self respecting designer might use on a = basic LF receiver converter

A level 13 mixer (+13dBm) wpouild give a proprtionately higher TO= IP, perhaps +25 to +30dBm
For higher linearity / better strong signal handling still, = a bus-switch mixer offers a TOIP perhaps +35 to +45dBm.   L= ike the Softrock receivers


<= /DIV>

On 14 July 2018 at 12:13, N1BUG <paul@n1bug.co= m> wrote:
Ouch! Having operated on= 160m and the HF bands for several years
using a receiver that come= s in at about -63 dB on 2 kHz spacing
third-order IMD I would never= again buy something with that kind of
receiver "performance".
<= BR>Paul N1BUG


On 07/06/2018 09:45 PM, jrusgrove@comcast.net wrote:
> Saw the w= riteup in QST and immediately noticed the receive
> two-tone, th= ird-order IMD at 2 kHz spacing is 60 dB and at 75 kHz
> spacing = is only 74 dB! Good luck with that if you've got strong
> signal= s at your location.
>
> Jay W1VD  WD2XNS  WE2XG= R/2


--GjF3Ncb12ueMkjNr2dpcCV7ID=_G6IpMKN--