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 w0PL2nKi005818 for ; Thu, 25 Jan 2018 22:02:51 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1eeobt-0006lF-1m for rs_out_1@blacksheep.org; Thu, 25 Jan 2018 20:59:01 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1eeobs-0006l6-Hj for rsgb_lf_group@blacksheep.org; Thu, 25 Jan 2018 20:59:00 +0000 Received: from omr-a014e.mx.aol.com ([204.29.186.62]) by relay1.thorcom.net with esmtps (TLSv1:DHE-RSA-AES256-SHA:256) (Exim 4.89) (envelope-from ) id 1eeobo-00040I-58 for rsgb_lf_group@blacksheep.org; Thu, 25 Jan 2018 20:58:59 +0000 Received: from mtaout-aag01.mx.aol.com (mtaout-aag01.mx.aol.com [172.26.126.77]) by omr-a014e.mx.aol.com (Outbound Mail Relay) with ESMTP id 84B543800099 for ; Thu, 25 Jan 2018 15:58:53 -0500 (EST) Received: from MichaelSappPC (MichaelSappPC [74.111.113.147]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mtaout-aag01.mx.aol.com (MUA/Third Party Client Interface) with ESMTPSA id 092373800008E for ; Thu, 25 Jan 2018 15:58:53 -0500 (EST) Message-ID: <5229DA849DB74A17B89CF81AFB611EB2@MichaelSappPC> From: "Michael Sapp" To: References: <001a01d394ff$8f3f54a0$adbdfde0$@go2.pl> <00c801d3960f$4ce1ab10$e6a50130$@go2.pl> <2B993CD1387E48D689FB9EF68B409ABB@Mike2PC> In-Reply-To: Date: Thu, 25 Jan 2018 15:58:47 -0500 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 V6.0.6002.19705 x-aol-global-disposition: G x-aol-sid: 3039ac1a7e4d5a6a450d3575 X-AOL-IP: 74.111.113.147 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 the administrator of that system for details. Content preview: Roger: Yes I find having the IPO "selected" is required which I believe means having the preamp "off" effectively, so we are in agreement. It is somewhat surprising but not entirely so how the FT-817 hears well at LF/MF with a good LPF filter in line. [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- 0.0 HTML_MESSAGE BODY: HTML included in message 0.0 T_REMOTE_IMAGE Message contains an external image X-Scan-Signature: b322dc0956bb435e223041a6879534f9 Subject: re:Re: LF: Re: 136kHz WSPR experiment Content-Type: multipart/alternative; boundary="----=_NextPart_000_000A_01D395F5.63891250" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.7 required=5.0 tests=HTML_20_30,HTML_MESSAGE, HTML_TAG_EXISTS_TBODY,MISSING_OUTLOOK_NAME 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. ------=_NextPart_000_000A_01D395F5.63891250 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Roger: Yes I find having the IPO "selected" is required which I = believe means having the preamp "off" effectively, so we are in = agreement. It is somewhat surprising but not entirely so how the = FT-817 hears well at LF/MF with a good LPF filter in line. I may give your 137 kHz E-probe a go with a high-Q inductor made with = FT50-61 material. It would be curious to see the response versus a lower = Q 77 or 75 high permeability core....somehow a half mH air wound version = would not seem to fit well in the box ~:) Thanks for the postings, 73, Mike wa3tts ----- Original Message -----=20 From: Roger Lapthorn=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Thursday, January 25, 2018 3:48 PM Subject: Re: LF: Re: 136kHz WSPR experiment Thanks Mike. I seem to remember that I got surprisingly good results = with my EFP (schematic shown a few days ago) feeding into the FT817 on = 136kHz, This has not be tried since before my 2013 stroke. If I am = correct the EFP is in a drawer somewhere! I shall have to try to find = it. I have a lot of junk. Next season I shall try the EFP on 136kHz RX. BTW, I find sensitivity on 136kHz with the FT817 is better with IPO = selected. Maybe this relates to your findings? 73s Roger G3XBM On 25 January 2018 at 20:31, Michael Sapp wrote: Roger: I tried to post a reply to the group prior but it did = apparently did not make it past the admin monitor or it exceeded message = size limit. I found the key to getting the FT-817 to receive well on LF and MF = is to use a low pass filter with good in-band return loss = characteristics between the antenna (e-probe, EWE, etc.) and the=20 FT-817. If you have ever tried listening to an AM broadcast station = with the FT-817 and it's VHF rubber duck antenna, you know it is = stone-cold deaf that way. But if you use an antenna with a reasonable = 50 ohm match at lower HF, the FT-817 hears AM band stations (530 ~ 1600 = kHz) very well. The same principle applies to LF/MF in the 100kHz to 500 = kHz range. The FT-817 receiver front end needs to see something close = to 50 ohms to receive signals efficiently. But it also needs most of = the AM band energy rejected so it will not overload. Using an LPF with = a good pass band match seems to solve the problem when using an e-probe = antenna at LF/MF with the FT-817. Also do not use the preamp in the = FT-817. Turn off the AGC and NB. There is a VE7BPO NDB filter with build information online that is = easy to construct with commonly available parts if you do not have an = LF/MF LPF filter available. I'm sure if you try it or another good LF/MF = LPF with your FT-817 you will see an immediate order-of-magnitude = improvement in receive performance at LF/MF. I use a variation of the = VE7BPO filter for 630m and a 9th order 300 kHz Butterworth LPF for LF. = The Butterworth LPFs have very good pass-band return loss and the FT-817 = responds very well to having the filter between the antenna and the = radio at LF. For even better performance I run a broadband LF/MF 2N3904 preamp = after my LPF and either a 3dB pad or a 50 ohm universal diplexer for the = frequency of interest after the preamp and into the FT-817. I built the = 2N3904 preamp last night to try it out based on your recent FT-817 LF = postings... Last night I was able to decode WH2XXP in AZ from PA with the FT-817 = at some 3000 km distant 55 times with the FT-817 on the 2200m band. I = was just able to occasionally decode WH2XXP with only the LPF and no = post filter preamp. With the 2N3904 preamp into a 3 dB pad and then = into the FT-817 I was able to obtain a best overnight SNR of -18 on = WH2XXP at 3000 km distant. I did need to use the attenuator in the = FT-817 to adjust the rx level. Quick sketch of preamp and FT-817 rx layout... https://www.dropbox.com/s/tmszk33xuyjjtnc/2N3904P.JPG?dl=3D0 Pix of filter-preamp setup but with 137 kHz diplexer on preamp = output instead of 3 dB pad... https://www.dropbox.com/s/tms4gruu2x8azz4/flpredp.jpg?dl=3D0 73 Mike wa3tts Virus-free. www.avg.com =20 ------=_NextPart_000_000A_01D395F5.63891250 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable =EF=BB=BF
 Roger:  Yes I find having = the IPO=20 "selected" is required which I believe means having the preamp "off"=20 effectively, so we are in agreement.  It is somewhat  = surprising but=20 not entirely so how the FT-817 hears well at LF/MF with a good LPF = filter in=20 line.
 
I may give your 137 kHz E-probe a go = with a high-Q=20 inductor made with FT50-61 material. It would be curious to see the = response=20 versus a lower Q 77 or 75 high permeability core....somehow a half mH = air wound=20 version would not seem to fit well in the box ~:)
 
 
Thanks for the postings,  73, Mike = wa3tts
 
 
----- Original Message -----
From:=20 Roger=20 Lapthorn
Sent: Thursday, January 25, = 2018 3:48=20 PM
Subject: Re: LF: Re: 136kHz = WSPR=20 experiment

Thanks Mike. I seem to remember that I got surprisingly good = results with=20 my EFP (schematic shown a few days ago) feeding into the FT817 on = 136kHz, This=20 has not be tried since before my 2013 stroke. If I am correct the EFP = is in a=20 drawer somewhere! I shall have to try to find it. I have a lot of = junk.

Next season I shall try the EFP on 136kHz RX.

BTW, I find sensitivity on 136kHz with the FT817 is better with = IPO=20 selected. Maybe this relates to your findings?

73s
Roger G3XBM

On 25 January 2018 at 20:31, Michael Sapp = <wa3tts@verizon.net> wrote:
Roger: I tried to post a reply to the group prior but it did = apparently=20 did not make it past the admin monitor or it exceeded message size=20 limit.
 
I found the key to getting the FT-817 to receive well on LF and = MF is=20 to use a low pass filter with good in-band return loss = characteristics=20 between the antenna (e-probe, EWE, etc.) and the
FT-817.  If you have ever tried listening to an AM = broadcast=20 station with the FT-817 and it's VHF rubber duck antenna, you know = it is=20 stone-cold deaf that way.  But if you use an antenna with a = reasonable=20 50 ohm match at lower HF, the FT-817 hears AM band stations (530 ~ = 1600 kHz)=20 very well. The same principle applies to LF/MF in the 100kHz to 500 = kHz=20 range.  The FT-817 receiver front end needs to see something = close to=20 50 ohms to receive signals efficiently.  But it also needs most = of the=20 AM band energy rejected so it will not overload.  Using an LPF = with a=20 good pass band match seems to solve the problem when using an = e-probe=20 antenna at LF/MF with the FT-817.  Also do not use the preamp = in the=20 FT-817. Turn off the AGC and NB.
 
There is a VE7BPO NDB filter with build information online that = is easy=20 to construct with commonly available parts if you do not have an = LF/MF LPF=20 filter available. I'm sure if you try it or another good LF/MF LPF = with your=20 FT-817 you will see an immediate order-of-magnitude improvement in = receive=20 performance at LF/MF.  I use a variation of the VE7BPO filter = for 630m=20 and a 9th order 300 kHz Butterworth LPF for LF.  The = Butterworth LPFs=20 have very good pass-band return loss and the FT-817 responds very = well to=20 having the filter between the antenna and the radio at LF.
 
For even better performance I run a broadband LF/MF 2N3904 = preamp after=20 my LPF and either a 3dB pad or a 50 ohm universal diplexer for the = frequency=20 of interest after the preamp and into the FT-817.  I built the = 2N3904=20 preamp last night to try it out based on your recent FT-817 LF=20 postings...
 
Last night I was able to decode WH2XXP in AZ from PA with the = FT-817 at=20 some 3000 km distant 55 times with the FT-817 on the 2200m band. I = was just=20 able to occasionally decode WH2XXP with only the LPF and no post = filter=20 preamp.  With the 2N3904 preamp into a 3 dB pad and then into = the=20 FT-817 I was able to obtain a best overnight SNR of -18 on WH2XXP at = 3000 km=20 distant. I did need to use the attenuator in the FT-817 to adjust = the rx=20 level.
 
Quick sketch of preamp and FT-817 rx layout...
 
 
Pix of filter-preamp setup but with 137 kHz diplexer on = preamp =20 output instead of 3 dB pad...
 
 
73 Mike = wa3tts


Virus-free.=20 www.avg.com
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