Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mk05.r1000.mx.aol.com (Internet Inbound) with ESMTP id 706BF3800008A; Tue, 18 Dec 2012 03:43:15 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1TkskL-0002VX-7c for rs_out_1@blacksheep.org; Tue, 18 Dec 2012 08:41:53 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1TkskK-0002VO-LW for rsgb_lf_group@blacksheep.org; Tue, 18 Dec 2012 08:41:52 +0000 Received: from mail-ie0-f181.google.com ([209.85.223.181]) by relay1.thorcom.net with esmtps (TLSv1:RC4-SHA:128) (Exim 4.77) (envelope-from ) id 1TkskI-0001C2-P2 for rsgb_lf_group@blacksheep.org; Tue, 18 Dec 2012 08:41:51 +0000 Received: by mail-ie0-f181.google.com with SMTP id 16so418797iea.26 for ; Tue, 18 Dec 2012 00:41:28 -0800 (PST) X-DKIM-Result: Domain=gmail.com Result=Good and Known Domain DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=85dwxldbb7MdkR6JUGlpGYSnKOVZ3mWuE8sjbjm6bAU=; b=ZvL20Oek2Opm/QDNDCc20wiFyeZg1Dt//xqVT1uz730wdjurpm2XIpWv/yqqO/Agry Gcdq24AYyaTvOxQK96B73Kdnz9xSKzwtJkU769X1IJJ4rakj+I+FBgquoj0H7De3L4N4 dSWdrHcO1ECCI7WDRfXQLxTyj1GgpMNIPE4CgCRPyVrnP7MI7NQPqca59JYWWoiZF0Z+ 6NWBFNuNKfHb1QxwvzADMck839t8r+WKi4ekWcocgNjvMvF4QwhUI5SfeTdW75FerCvc L3Ubg4oQJz4Au2HDwWq0lH3nKixDn4B9uiKkibN9Q6a1huHNveQZjLRE/0ryz5tLXmcD JJmg== MIME-Version: 1.0 Received: by 10.50.12.138 with SMTP id y10mr1614904igb.58.1355820088794; Tue, 18 Dec 2012 00:41:28 -0800 (PST) Received: by 10.231.157.74 with HTTP; Tue, 18 Dec 2012 00:41:28 -0800 (PST) In-Reply-To: <20121218100332.Horde.2ASBc_rSz0VQ0CNU8mNkBhA@posti.anvianet.fi> References: <20121218092921.Horde.h2yZX_rSz0VQ0BtRPVIC2uA@posti.anvianet.fi> <20121218100332.Horde.2ASBc_rSz0VQ0CNU8mNkBhA@posti.anvianet.fi> Date: Tue, 18 Dec 2012 19:41:28 +1100 Message-ID: From: Dimitrios Tsifakis To: rsgb_lf_group@blacksheep.org X-Spam-Score: -0.7 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: I am glad you found the eBay seller and your project is about to be revived. A VFO, as David G4DMP mentioned before, is also another valid option. It shouldn't be too hard to make a VFO stable enough for 472 kc, even if it is a valve one! As a test, I built a VFO for 7 Mc using a 6C4 oscillator and a 6AG7 as a BA - it was perfectly good for CW work. [...] 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 [209.85.223.181 listed in list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (dtsifakis[at]gmail.com) -0.0 SPF_PASS SPF: sender matches SPF record 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: 4d97240a623a26620214cd27feaa9f71 Subject: Re: LF: FT-241A xtals? Content-Type: text/plain; charset=ISO-8859-1 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=none 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 x-aol-global-disposition: G X-AOL-SCOLL-AUTHENTICATION: mtain-mk05.r1000.mx.aol.com ; domain : gmail.com DKIM : pass x-aol-sid: 3039ac1d618950d02ca321a3 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none I am glad you found the eBay seller and your project is about to be revived. A VFO, as David G4DMP mentioned before, is also another valid option. It shouldn't be too hard to make a VFO stable enough for 472 kc, even if it is a valve one! As a test, I built a VFO for 7 Mc using a 6C4 oscillator and a 6AG7 as a BA - it was perfectly good for CW work. I hope we can exchange more technical information about both projects here. Maybe this will be a source of inspration for others that have considered the possibility of using valves for a 472 kc transmitter. 73, Dimitris VK1SV 2012/12/18 : > What a coincidence Dimitros! > > After answering to your posting I did a search on Ebay for FT-241 crystals > and found the same seller - an order has already been made :) > > Many thanks for bringing up this subject - I had lost hope already. > > > > Paul-Henrik, OH1LSQ > > > Quoting Dimitrios Tsifakis : > >> Hi Paul-Henrik, >> >>> Yes, the same thought has been on my mind for a long time now. The >>> problem >>> is that fundamental X-tals for this frequency band are nearly >>> unobtainable. >>> I have even tried to custom order some new ones for me and a couple of >>> friends but never succeeded - the quantities would need to be much larger >>> for this type of crystals. (They use a different kind of cut as compared >>> to >>> crystals for say 3500kHz which can still be ordered custom fairly easily) >>> >>> Hopefully people with a stash of suitable vintage X-tals will wake up >>> when >>> the new band opens for real and put some up for sale if they don't want >>> to >>> use them themselves. >> >> >> I bought a few crystals from this ebay seller: >> >> >> http://www.ebay.com.au/itm/FT-241-CRYSTALS-Many-to-choose-from-You-pick-/260897401407?pt=LH_DefaultDomain_0&hash=item3cbeb26a3f&_uhb=1#ht_4373wt_1188 >> >> There seem to be a few left. They are sold as-is, but I found that the >> majority of the ones I bought worked OK. There may be other sellers on >> eBay. >> >>> I'd say go for it - I have built a couple of "MO-PA" transmitters for >>> 80/160m, they are really pleasant and rewarding projects with a distinct >>> sound of their own. This is especially true if you also key the >>> oscillator. >> >> >> I have built recently a similar transmitter for 40 m, using a 6CL6 and >> an 807. When I keyed the oscillator together with the PA, I couldn't >> get it to behave properly, so I added a switch to leave the oscillator >> on and key only the cathode of the PA. I only key the oscillator when >> I want to draw some attention with the home-brew sound! >> >> In general, I have had difficulty sourcing a HV transformer suitable >> for an 807. In the past, I found that one can build a voltage doubler >> or quadrupler, with modern electrolytics, it is a viable alternative. >> The 6.3 V for the filaments I found I can get from a 6 V transformer. >> Hint: it's easy to add extra turns on a toroid type transformer :-) >> >> 73, Dimitris VK1SV > > > > >