Return-Path: X-Spam-DCC: paranoid 1290; Body=3 Fuz1=3 Fuz2=3 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, FORGED_RCVD_HELO,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 t4K5eXLi026705 for ; Wed, 20 May 2015 07:40:33 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1YuwgS-0006Oj-9m for rs_out_1@blacksheep.org; Wed, 20 May 2015 06:36:48 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1YuwgR-0006Oa-G7 for rsgb_lf_group@blacksheep.org; Wed, 20 May 2015 06:36:47 +0100 Received: from rhcavuit02.kulnet.kuleuven.be ([134.58.240.130] helo=cavuit02.kulnet.kuleuven.be) by relay1.thorcom.net with esmtp (Exim 4.85) (envelope-from ) id 1YuwgP-0002kP-7r for rsgb_lf_group@blacksheep.org; Wed, 20 May 2015 06:36:46 +0100 X-KULeuven-Envelope-From: rik.strobbe@fys.kuleuven.be X-KULeuven-Scanned: Found to be clean X-KULeuven-ID: D771212808A.A4545 X-KULeuven-Information: Katholieke Universiteit Leuven Received: from icts-p-smtps-2.cc.kuleuven.be (icts-p-smtps-2e.kulnet.kuleuven.be [134.58.240.34]) by cavuit02.kulnet.kuleuven.be (Postfix) with ESMTP id D771212808A for ; Wed, 20 May 2015 07:36:38 +0200 (CEST) Received: from ICTS-S-HUB3.luna.kuleuven.be (icts-s-hub3.luna.kuleuven.be [10.112.9.17]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (No client certificate requested) by icts-p-smtps-2.cc.kuleuven.be (Postfix) with ESMTPS id D4DC32003B for ; Wed, 20 May 2015 07:36:35 +0200 (CEST) Received: from ICTS-S-MBX1.luna.kuleuven.be ([fe80::edaf:341f:90e:f70e]) by ICTS-S-HUB3.luna.kuleuven.be ([fe80::a470:76b3:406d:2b1a%27]) with mapi id 14.03.0224.002; Wed, 20 May 2015 07:36:34 +0200 X-Kuleuven: This mail passed the K.U.Leuven mailcluster From: Rik Strobbe To: "rsgb_lf_group@blacksheep.org" Thread-Topic: FZ-02-B mechanical filter input matching Thread-Index: AQHQknsQBYw2ohGDTUyEmSbi6K37PZ2EVs/q Date: Wed, 20 May 2015 05:36:35 +0000 Message-ID: <7E7DFBB4D102A04DB5ADC88D66628A4A235480A8@ICTS-S-MBX1.luna.kuleuven.be> References: <555BAAF1.4020800@posteo.de> In-Reply-To: <555BAAF1.4020800@posteo.de> Accept-Language: nl-BE, en-GB, en-US Content-Language: nl-BE X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.112.13.12] MIME-Version: 1.0 X-HELO-Warning: Remote host 134.58.240.130 (rhcavuit02.kulnet.kuleuven.be) used invalid HELO/EHLO cavuit02.kulnet.kuleuven.be - verification failed X-Scan-Signature: e2b7e65dcf7cf6551ab81105a525fe0f Subject: LF: RE: FZ-02-B mechanical filter input matching Content-Type: multipart/alternative; boundary="_000_7E7DFBB4D102A04DB5ADC88D66628A4A235480A8ICTSSMBX1lunaku_" 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: 3158 --_000_7E7DFBB4D102A04DB5ADC88D66628A4A235480A8ICTSSMBX1lunaku_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi Stefan, regarding: Now my question: Is it better to remove a BF981 amp stage (about 16 dB to 1= 8 dB gain!) in front of the mixer (SBL-3) to get a lower RX noise or do i b= etter reduce the gain on the LT1028 stage on the AF side? The AF pass band = is 11...18 kHz (LO=3D 461 kHz) On MF one must have a very small RX antenna before the internal RX noise be= comes dominant to the external noise. Using my 475kHz antenna (lazy-L 12m high, 25m long) and a Kenwood TS440 as = RX I can attenuate the antenna signal by 40dB or more before the antenna no= ise drops below the RX noise. So I think that in regard with SNR it will not really matter wether you rem= ove the preamp of reduce gain in the LF stage. 73, Rik ON7YD - OR7T ________________________________ Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org= ] namens DK7FC [selberdenken@posteo.de] Verzonden: dinsdag 19 mei 2015 23:28 Aan: rsgb_lf_group@blacksheep.org Onderwerp: LF: FZ-02-B mechanical filter input matching Hi MF, Some of you are using the old Telefunken mechanical filter in homemade rece= ivers for 630m. I use them i all my MF receivers. There have been discussions about how to match the antenn to that filter. So far, i used this matching method: https://dl.dropboxusercontent.com/u/19= 882028/MF/MF%20Filter%20schematic.png (recently using the 500 Ohm input rat= her than the 18k input) i.e. an active impedance converter stage. This has a few advantages: -The input of the filter can be matched perfectly to the jFET, giving a min= imun pass band ripple (less than 1 dB) -The matching is independent of the impedance of the voltage source connect= ed to the input of the jFET -You can use a 50 Ohm resitor on the input of the jFET, giving a perfect ma= tching of the cable for all frequencies -The input can even be used as an active antenna (very high Z) -Many receiver inputs can be switched in parallel! For example a LF RX para= llel to a MF RX plus one 50 Ohm resistor... -The input of the mechanical filter must not be exceeded to a voltage above= 2 V rms (inside the passband or on any frequency?????) So, if the jFET is = driven at 5V supply voltage, the filter is protected against overvoltages! These were the arguments why i decided to use this technique so far. Here i= s an image of the RX on my remote site, captured today: https://dl.dropboxu= sercontent.com/u/19882028/MF/MF%20mechanical%20filter%20active%20input.jpg But now, on my remote RX site i have a relatively large RX antenna (T, 5m V= , 20m H) with a 50 Ohm matching. Furthermore i want to reduce the power con= sumption of the RX system. And i want to try to improve the RX performance = even more. So i've made a modification, a simple transformer matching (noth= ing new!!!!!!!) as recently discussed. Here the advanatges are: -No active parts in front of the mechanical filter, just wire, Ls, Cs, cabl= e and ferrite cores! -One active stage less, i.e. less power consumption, about 10 mA at 12V, i.= e. 0.24 Ah per day! -A 'gain' (relative to the active stage which has a voltage gain of - 6 dB = due to the resistor matching) of 16 dB (confirmed by measurements on SpecLa= b) because the transformer makes 10 dB when transforming from 50 Ohm to the= 500 Ohm input of the filter -This gain makes one of the following amp stages obsolete, i.e. likely i ca= n remove one more active stage which will result in even less power consump= tion, maybe 0.5 Ah per day, which is much in winter! -Maybe less RX noise? -Maybe less unwanted IM products?? Here is an image of the simple new input matching https://dl.dropboxusercon= tent.com/u/19882028/MF/MF%20mechanical%20filter%20passive%20input.jpg One of the advantages of the active input matching is missing now: the perf= ect matching. The pass band ripple is now about 2 dB but this is still acce= ptable for me if there are some advantages on the other side. The second amp stage is not yet removed in my currently running RX, so ther= e is to much gain in the moment, i.e. a smaller dynamic range. I just wante= d to confirm the 16 dB to decide the next steps. Now my question: Is it better to remove a BF981 amp stage (about 16 dB to 1= 8 dB gain!) in front of the mixer (SBL-3) to get a lower RX noise or do i b= etter reduce the gain on the LT1028 stage on the AF side? The AF pass band = is 11...18 kHz (LO=3D 461 kHz) 73, Stefan/DK7FC --_000_7E7DFBB4D102A04DB5ADC88D66628A4A235480A8ICTSSMBX1lunaku_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Hi Stefan,

 

regarding:

Now my question: Is = it better to remove a BF981 amp stage (about 16 dB to 18 dB gain!) in front= of the mixer (SBL-3) to get a lower RX noise or do i better reduce the gai= n on the LT1028 stage on the AF side? The AF pass band is 11...18 kHz (LO=3D 461 kHz)

On MF one must have a very small RX antenna before the internal RX = noise becomes dominant to the external noise.

Using my 475kHz antenna (lazy-L 12m high, 25m long) and a Kenwood TS440 = as RX I can attenuate the antenna signal by 40dB or more before the antenna= noise drops below the RX noise.

So I think that in regard with SNR it will not really matter wether you = remove the preamp of reduce gain in the LF stage.

 

73, Rik  ON7YD - OR7T

 

Van: owner-rsgb_lf_group@blacksheep.org [o= wner-rsgb_lf_group@blacksheep.org] namens DK7FC [selberdenken@posteo.de] Verzonden: dinsdag 19 mei 2015 23:28
Aan: rsgb_lf_group@blacksheep.org
Onderwerp: LF: FZ-02-B mechanical filter input matching

Hi MF,

Some of you are using the old Telefunken mechanical filter in homemade rece= ivers for 630m. I use them i all my MF receivers.

There have been discussions about how to match the antenn to that filter. <= br> So far, i used this matching method: https://dl.dropboxusercontent.com/u/19882028/MF/MF%20Filter%20schematic.png= (recently using the 500 Ohm input rather than the 18k input) i.e. an a= ctive impedance converter stage.
This has a few advantages:
-The input of the filter can be matched perfectly to the jFET, giving a min= imun pass band ripple (less than 1 dB)
-The matching is independent of the impedance of the voltage source connect= ed to the input of the jFET
-You can use a 50 Ohm resitor on the input of the jFET, giving a perfect ma= tching of the cable for all frequencies
-The input can even be used as an active antenna (very high Z)
-Many receiver inputs can be switched in parallel! For example a LF RX para= llel to a MF RX plus one 50 Ohm resistor...
-The input of the mechanical filter must not be exceeded to a voltage above= 2 V rms (inside the passband or on any frequency?????) So, if the jFET is = driven at 5V supply voltage, the filter is protected against overvoltages!<= br> These were the arguments why i decided to use this technique so far. Here i= s an image of the RX on my remote site, captured today: https://dl.dropboxusercontent.com/u/19882028/MF/MF%20mechanical%20filter%20= active%20input.jpg

But now, on my remote RX site i have a relatively large RX antenna (T, 5m V= , 20m H) with a 50 Ohm matching. Furthermore i want to reduce the power con= sumption of the RX system. And i want to try to improve the RX performance = even more. So i've made a modification, a simple transformer matching (nothing new!!!!!!!) as recently discussed.<= br> Here the advanatges are:
-No active parts in front of the mechanical filter, just wire, Ls, C= s, cable and ferrite cores!
-One active stage less, i.e. less power consumption, about 10 mA at 12V, i.= e. 0.24 Ah per day!
-A 'gain' (relative to the active stage which has a voltage gain of = - 6 dB due to the resistor matching) of 16 dB (confirmed by measurements on SpecLab) because the transfor= mer makes 10 dB when transforming from 50 Ohm to the 500 Ohm input of the f= ilter
-This gain makes one of the following amp stages obsolete, i.e. likely i ca= n remove one more active stage which will result in even less power consumption, maybe 0.5 Ah per day, which is much in winte= r!
-Maybe less RX noise?
-Maybe less unwanted IM products??

Here is an image of the simple new input matching https://dl.dropboxusercontent.com/u/19882028/MF/MF%20mechanical%20filter%20= passive%20input.jpg
One of the advantages of the active input matching is missing now: the perf= ect matching. The pass band ripple is now about 2 dB but this is still acce= ptable for me if there are some advantages on the other side.

The second amp stage is not yet removed in my currently running RX, so ther= e is to much gain in the moment, i.e. a smaller dynamic range. I just wante= d to confirm the 16 dB to decide the next steps.

Now my question: Is it better to remove a BF981 amp stage (ab= out 16 dB to 18 dB gain!) in front of the mixer (SBL-3) to get a lower RX n= oise or do i better reduce the gain on the LT1028 stage on the AF side? The= AF pass band is 11...18 kHz (LO=3D 461 kHz)

73, Stefan/DK7FC
--_000_7E7DFBB4D102A04DB5ADC88D66628A4A235480A8ICTSSMBX1lunaku_--