X-GM-THRID: 1242246556838609221 X-Gmail-Labels: rsgb lf Delivered-To: daveyxm@gmail.com Received: by 10.78.172.11 with SMTP id u11cs327251hue; Tue, 17 Jul 2007 11:57:16 -0700 (PDT) Received: by 10.86.97.7 with SMTP id u7mr524936fgb.1184698636287; Tue, 17 Jul 2007 11:57:16 -0700 (PDT) Return-Path: Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mx.google.com with ESMTP id d26si34924447nfh.2007.07.17.11.57.11; Tue, 17 Jul 2007 11:57:16 -0700 (PDT) Received-SPF: neutral (google.com: 193.82.116.20 is neither permitted nor denied by best guess record for domain of owner-rsgb_lf_group@blacksheep.org) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1IAs8y-0005ZI-CG for rs_out_1@blacksheep.org; Tue, 17 Jul 2007 19:51:32 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1IAs8x-0005Z9-EV for rsgb_lf_group@blacksheep.org; Tue, 17 Jul 2007 19:51:31 +0100 Received: from hexagon.inweb.co.uk ([213.210.47.3]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1IAs8s-0003Xb-4O for rsgb_lf_group@blacksheep.org; Tue, 17 Jul 2007 19:51:31 +0100 Received: from VicsLaptop (82-133-107-50.dyn.gotadsl.co.uk [82.133.107.50]) by hexagon.inweb.co.uk (Postfix) with SMTP id 79E432602D9 for ; Tue, 17 Jul 2007 19:51:24 +0100 (BST) Message-ID: <006701c7c8a3$794be570$2201a8c0@VicsLaptop> From: "Vic@VicsFloridaVilla" To: References: Date: Tue, 17 Jul 2007 19:51:24 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3138 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3138 X-Karma: 0: X-Spam-Score: 0.3 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,MAILTO_TO_SPAM_ADDR=0.276 Subject: LF: Re: RE: LF 500khz Content-Type: multipart/alternative; boundary="----=_NextPart_000_0064_01C7C8AB.DAEC98D0" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=2.0 required=5.0 tests=HTML_30_40,HTML_FONTCOLOR_BLUE, HTML_MESSAGE,MAILTO_TO_SPAM_ADDR 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 Status: O X-Status: X-Keywords: X-UID: 1230 This is a multi-part message in MIME format. ------=_NextPart_000_0064_01C7C8AB.DAEC98D0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi Dave, Many thanks for your reply and sincere apologies for this delayed = response - too much non radio work :-( !!! I would ceratinly appreciate a scan of your tx design . That would give = me a good start. My design skills are rather limited - my only rf = qualification is the RAE which I tookin 1978 but I love tinkering and = homebrew. Having built a K2 and recently a KX1 I have gained a lot of = confidence to have a crack at a 500khz rig. So far the transverter = looks very promising.=20 Having followed the postings on the reflector I agree a pre selector on = rx looks essential and I think a resonant antenna. But some stations = seem to get quite good results with fairly modest antennas so there is = hope ! My progress on 500 will be slow due to other comittments but I am = determined to put out a signal on that band ! Many thanks again ! 73, Vic=20 GW4JUN ----- Original Message -----=20 From: Dave G3WCB=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Saturday, May 19, 2007 11:33 PM Subject: LF: RE: LF 500khz Hi, Vic. I've got no experince with the K2, but you'll probably need a = pre-selector to get the best performance out of your rig on 500 kHz. I = use a simple design with a fet front end, which can be found on G3YXM's = web-site:- http://www.wireless.org.uk/circuits2.htm I substituted a = J310 fet for the BF245, and used IFTs from a junked transistor radio for = the inductors. My RX is an Icom IC-PCR1000 which is okay, but the IF = filter is a bit wide for close-in CW work. For transmitting, I use a design by DF3LP, which was originally for = 137 kHz http://www.qsl.net/df3lp/projects/lftx/index.html It uses an = IRF 540 FET as the output stage, and I have no trouble getting 25W into = 50 ohms from a 12VDC supply, although you may not need this much power = to hit the 100 mW ERP limit if you have a reasonable antenna. You can scavenge most of the bits for nothing from scrap PC power = supplies, including the case and fan! The DF3LP TX design uses a crystal-mixer VFO, but you could omit this = and feed your 1mW straight into the second BC549 transistor. You'd need = to re-do the pi-section filters for operation at 500 kHz, but you just = need to scale the inductance value by the ratio 137/500. I've got a = scanned copy of my TX circuit if you are interested. Quite a few 500 kHz OPS are using valve TXs, with bottles like ECL82, = and 2E26s. It just depends what you are happiest using! 73, Dave G3WCB IO91RM -----Original Message----- From: owner-rsgb_lf_group@blacksheep.org = [mailto:owner-rsgb_lf_group@blacksheep.org]On Behalf Of = Vic@VicsFloridaVilla Sent: 19 May 2007 21:05 To: rsgb_lf_group@blacksheep.org Subject: LF: LF 500khz Hi Folks, Joined the list a couple of weeks ago amd enjoying reading all the = postings but this is my first posting. I am planning to use my Elecraft K2 to drive a homebrew transverter = to give me a 500khz capability. I have the transverter interface board = in the K2 so have a 1mW output available. So far I hace lashed up a 28Mhz xtal oscillator and a home brew = diode ring mixer. Feeding these through a G0MRF 7 element Low Pass = Filter I tested it the other night and it works ! Wow. Nice clean cw and = ssb on 500khz (feeding directly into my receiver....probably the first = and last time I'll hear ssb on 500khz !!) Amazing carrier suppression on = ssb - really impressive for 4 IN4148 diodes and a couple of FT50-43 = cores. Plenty of attenuation of 1000khz and 1500khz harmonics. It's = looking good ! Just tried it on receive and it does work but signals very weak. = With the K2 pre amp on I can hear MSF 60Khz at S1 , Loran 100Khz at S4, = BBc R4 198Khz at S9, plus a few other data type sigs below 150khz. Heard = nothing on 500Khz . I can hear a strong intermittent data type signal on = about 518Khz Plenty of noise when I connect the antenna though. Looks = like I may need to work on the antenna and maybe some receive = amplification . I'm thrilled with all this so far but now I need some help with the = rest of the system.=20 So a few questions for you all, and any ideas and suggestions = gratefully received ! 1) Can anyone point me to any designs for a pa suitable for 500khz. = Something around 5 - 10 watts output from about 1mW input would be = great. I am not very knowledgable on electronics but I love tinkering so = something which is easy to get going would be good. I imagine at 500khz = it should not be too difficult. 2) Has anyone on the list used a K2 with the transverter board to = drive a transveter ? I can get a full 1mW tx output into a 50 ohm dummy = load (as per the construction manual) but when driving my homebrew ring = mixer I can only get about 0.3 mW maximum. I wonder if there is an = impedance mismatch which is loading the K2 output. The K2 is connected = directly to the mixer. My mixer has six trifilar turns on a FT50-43 at = each end. It clearly works well but I think I'll need to get the level = up a bit at some point.=20 3) Thinking ahead to antennas.....I'll need to do something to = resonate my 180 ft Inv L . I 'll probably stick a big loading coil in it = somewhere but I have no idea how much L I'll need . Is there any = software out there which will help me with this ? Meanwhile I'll press on with the band pass filter which is not = working so well . Time for a tinker !! TIA 73, Vic GW4JUN Halkyn North Wales IO83JF -------------------------------------------------------------------------= ----- No virus found in this incoming message. Checked by AVG Free Edition.=20 Version: 7.5.467 / Virus Database: 269.7.4/811 - Release Date: = 18/05/2007 15:50 ------=_NextPart_000_0064_01C7C8AB.DAEC98D0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hi Dave,
 
Many thanks for your reply = and sincere=20 apologies for this delayed response - too much non radio work = :-(  =20 !!!
 
I would ceratinly appreciate = a scan of=20 your tx design . That would give me a good start. My design skills are = rather=20 limited - my only rf qualification is the RAE which I tookin 1978 but I = love=20 tinkering and homebrew. Having built a K2 and recently a KX1 I have = gained a lot=20 of confidence to have  a crack at a 500khz rig. So far the = transverter=20 looks very promising.
 
Having followed the postings = on the=20 reflector I agree a pre selector on rx looks essential and I think a = resonant=20 antenna. But some stations seem to get quite good results with fairly = modest=20 antennas so there is hope !
 
My progress on 500 will be = slow due to=20 other comittments but I am determined to put out a signal on that band=20 !
 
Many thanks again = !
 
73,
 
Vic
 
GW4JUN
----- Original Message -----
From:=20 Dave G3WCB
Sent: Saturday, May 19, 2007 = 11:33=20 PM
Subject: LF: RE: LF = 500khz

Hi,=20 Vic.
 
I've=20 got no experince with the K2, but you'll probably need a pre-selector = to get=20 the best performance out of your rig on 500 kHz. I use a simple = design=20 with a fet front end, which can be found on G3YXM's web-site:- =20 http://www.wireless.org= .uk/circuits2.htm  =20 I substituted a J310 fet for the BF245, and used IFTs from a junked = transistor=20 radio for the inductors. My RX is an Icom IC-PCR1000 which is okay, = but the IF=20 filter is a bit wide for close-in CW work.
 
For=20 transmitting, I use a design by DF3LP, which was originally for 137 = kHz=20 http://www.qsl.net/df3lp/projects/lftx/index.html   It uses an IRF 540 FET as the output = stage,=20 and I have no trouble getting 25W into 50 ohms from a 12VDC supply, = although=20 you may not need this much power to hit the 100 mW ERP limit if = you have=20 a reasonable antenna.
 
You can scavenge most of the bits for = nothing from=20 scrap PC power supplies, including the case and=20 fan!
 
The DF3LP TX design uses a crystal-mixer = VFO, but you=20 could omit this and feed your 1mW straight into the second BC549 = transistor.=20 You'd need to re-do the pi-section filters for operation at 500 kHz, = but you=20 just need to scale the inductance value by the = ratio 137/500. I've=20 got a scanned copy of my TX circuit if you are=20 interested.
 
Quite a few 500 kHz OPS are using valve = TXs, with=20 bottles like ECL82, and 2E26s. It just depends what you are happiest=20 using!
 
73, Dave G3WCB=20 IO91RM
 
 
 
-----Original Message-----
From:=20 owner-rsgb_lf_group@blacksheep.org=20 [mailto:owner-rsgb_lf_group@blacksheep.org]On Behalf Of=20 Vic@VicsFloridaVilla
Sent: 19 May 2007 = 21:05
To:=20 rsgb_lf_group@blacksheep.org
Subject: LF: LF=20 500khz

Hi Folks,
 
 
Joined the list a couple = of weeks ago=20 amd enjoying reading all the postings but this is my first=20 posting.
 
I am planning to use my = Elecraft K2=20 to drive a homebrew transverter to give me a 500khz capability. I = have the=20 transverter interface board in the K2 so have a 1mW output=20 available.
 
So far I hace lashed up a = 28Mhz xtal=20 oscillator and a home brew diode ring mixer. Feeding these through a = G0MRF 7=20 element Low  Pass Filter I tested it the other night and it = works !=20 Wow. Nice clean cw and ssb on 500khz (feeding directly into my=20 receiver....probably the first and last time I'll hear ssb on 500khz = !!)=20 Amazing carrier suppression on ssb - really impressive for 4 IN4148 = diodes=20 and a couple of FT50-43 cores. Plenty of attenuation of 1000khz and = 1500khz=20 harmonics. It's looking good !
 
Just tried it on receive = and it does=20 work but signals very weak. With the K2 pre amp on I can hear MSF = 60Khz at=20 S1 , Loran 100Khz at S4, BBc R4 198Khz at S9, plus a few other = data=20 type sigs below 150khz. Heard nothing on 500Khz . I can hear a = strong=20 intermittent data type signal on about 518Khz Plenty of noise=20 when I connect the antenna though. Looks like I may need to = work on the=20 antenna and maybe some receive amplification .
 
I'm thrilled with all = this so=20 far  but now I need some help with the rest of the system.=20
 
So a few questions for = you all, and=20 any ideas and suggestions gratefully received !
 
1) Can anyone point me to = any designs=20 for a pa suitable for 500khz. Something around 5 - 10 watts output = from=20 about 1mW input would be great. I am not very knowledgable on = electronics=20 but I love tinkering so something which is easy to get going would = be good.=20 I imagine at 500khz it should not be too difficult.
 
2) Has anyone on the list = used a K2=20 with the transverter board to drive a transveter ? I can get a full = 1mW tx=20 output into a 50 ohm dummy load (as per the construction manual) but = when=20 driving my homebrew ring mixer I can only get about 0.3 mW maximum. = I wonder=20 if there is an impedance mismatch which is loading the K2 = output.  The=20 K2 is connected directly to the mixer.  My mixer has six = trifilar turns=20 on a FT50-43 at each end. It clearly works well but I think I'll = need to get=20 the level up a bit at some point.
 
3) Thinking ahead to=20 antennas.....I'll need to do something to resonate my 180 ft Inv L . = I 'll=20 probably stick a big loading coil in it somewhere but I have no idea = how=20 much L I'll need . Is there any software out there which will help = me with=20 this ?
 
Meanwhile I'll press on = with the band=20 pass filter which is not working so well . Time for a tinker = !!
 
TIA
 
73,
 
Vic GW4JUN
 
Halkyn North Wales=20 IO83JF

No virus found in this incoming message.
Checked by AVG Free = Edition.
Version: 7.5.467 / Virus Database: 269.7.4/811 - Release = Date:=20 18/05/2007 15:50
------=_NextPart_000_0064_01C7C8AB.DAEC98D0--