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eHam Forums / Boat Anchors / RE: Kenwood TS-430S Filters
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on: March 29, 2013, 02:20:31 PM
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Kenwood TS-430 Owner's Manual http://www.usersmanualguide.com/kenwood/amateur_radio/ts-430sTurn to page 20, Section 6-2 Installation of Optional FiltersPictorials: Figure 6-1 and Figure 6-3 show proper jumper configurations. === Turn to page 10, Section 5.1.8 NAR-WIDE switch operation The Passband Width Matrix table show all possible combinations. IF a switch setting does not work -- CHECK to see if former owner properly jumped AM filter.That would be on Page 20. |
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124
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eHam Forums / Amplifiers / RE: DENTRON MLA 2500
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on: March 28, 2013, 06:36:05 PM
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2008 Retrofit to an MLA2500 amp using the Eimac 3CX800 ceramic triodes done by Lawson, W4EMF http://w4emf.gs35b.com/mla2500-retro-3cx800-2008/index.html=== Tony King, W4ZT came up with a schematic diagram (July 2007) for converting the Dentron MLA-2500 to use TWO Russian surplus GI-7b ceramic triodes. http://gi7b.com/mla2500/mla2500mod.pdfW4EMF and K4POZ provided assistance and suggestion. http://w4emf.gs35b.com/mla2500-retro-gi7/index.htmlhttp://gi7b.com/mla2500/index.htmlModifications, in no particular order, that are shown on the schematic above: GI-7B tube retrofit. Cathode choke move from the ALC board to under chassis cathode connection. Input coupling capacitor change. Cutoff resistor and bias change. Adjustable Bias Board and bypass caps added. Glitch resistor change from a fuse resistor to a true glitch resistor. New grid shunt and protection diodes. Resistor value not specified on schematic. New plate current shunt and protection diodes. Resistor value not specified on schematic. Metering calibration resistors and pots added. Harbach SS-100 Step Start module added. Antenna Relay change to 3PDT Relay to allow keying the amp only after Antenna contacts are made. The third set of contacts is put in series with the bias keying relay and prevents hot switching the amp. Filament transformer added. Filament choke and bypass caps added. New and added filter capacitors, equalizing resistors and reverse protection diodes added. Dropping resistor in series with delay tube filament to make up for the unloaded filament winding. This value is found experimentally. Meter switch changes to properly switch the metering and calibration. === Based on this work, other amateurs have successfully documented this conversion. Dentron MLA-2500 GI7B Modification by N3OC, February 2013 http://n3oc.dyndns.org/GI7B.htm |
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eHam Forums / Amplifiers / RE: DENTRON MLA 2500
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on: March 28, 2013, 12:53:42 PM
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I thought this boat anchor was so old that nobody knew about it.
I didn't realize Dentron was still in business. SHORT HISTORY of Denny Had, founder of Dentron. http://en.wikipedia.org/wiki/Cary_Audio_DesignDennis Had was the founder of the Dentron Radio Company, owner and designer of the Ameritron amplifiers, and the Amp Supply Company.
Dentron Radio Manufactured all sorts of Amateur Radio gear; Amplifiers, and Tuners from 1960s to the early 1980s.
Amp Supply Company and Dentron are no longer in business. Ameritron is now owned by MFJ Enterprises.
Dentron, Ameritron and Amp Supply Company were all based originally in Ohio.
Amp Supply moved to Cary, North Carolina (late 1980s) and soon morphed into the Cary Audio Company.
Amp Supply was eventually closed. == Eimac 8873, 8874, and 8875 ceramic tube data sheets. http://www.ok1rr.com/tubes/eimac/8875.pdfThis FAMILY of Triode RF tubes only differ by the cooling and anode dissipation !! 8873 - Conduction cooling and rated for 200 Watts 8875 - Transverse cooler for forced-air cooling and is rated for 300 watts 8874 (3CX400) - Axial Flow forced-air cooling and is rated for 400 watts The Dentron MLA-2500 used TWO 8875 ceramic tubes. Eimac stopped production of the 8873 and 8875 over 20 years ago. The 8874 / 3CX400 ceramic triode tube is still produced by Eimac/CPI (USA) and Svetlana (Russia). Dentron MLA-2500 HF Amplifier Repair http://www.aa1zb.net/Radio/Dentron/Dentron.htmlThe easiest tube conversion is using the 8874 / 3CX400 or 3CX800 ceramic triodes. You ONLY need to change the cooling for axial flow. Uses the SAME socket. The 8874 tube was used by ETO Alpha (Dick Einhorn era) for their late 1970s to 1980s HF amplifiers (e.g. 374A, 76, 76A, 78) B.N. "Bob" Alper, W6KT -- Communications Quarterly magazine, Summer 1996Svetlana article for using Eimac 8874/3CX400A triode in Dentron MLA-2500. http://www.tube-town.net/info/sed-technotes/docs/technoteNo14.htmlNote: The economic differences mentioned in 1990s by W6KT - no longer exist - as surplus Russian 4CX800 are about same price as triodes now !DK9IP Conversion of MLA-2500 - January 2005 http://www.dk9ip.de/projects/mla2500/mla2500.html3CX400A/8874 or 3CX800A conversion instructions for the Dentron MLA-2500 by LX2KL http://195.84.101.101/~goranl/shack/amp_mla2500/convert_3cx800a.pdfNG9R performed this upgrade/change-out for his MLA-2500 in 2007 |
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eHam Forums / Amplifiers / RE: Source For Replacement Tube 811 , 380-0811A
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on: March 27, 2013, 12:17:31 PM
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Brian -- The parts are in UK, which is much closer to you (Cyprus). The 811A glass tube may still be mfg. at JJ/Tesla in Slovak Republic.http://www.jj-electronic.sk/JJ Electronic A. Hlinku 4 02201 Cadca Slovak Republic tel: +421/41/4304120 fax: +421/41/4335370 email: info@jj-electronic.com=== Waters & Stanton PLC, Spa House, 22 Main Road, Hockley, Essex. SS5 4QS. United Kingdom Tel +44(0)1702 206835 Fax +44(0)1702 205843 Opening Hours: Monday to Saturday 9.00am to 5.30pm. http://www.wsplc.com/In addition to Waters & Stanton, try the DX Shop ! Linear Amps UK was purchased by The DX Shop. The DX Shop is run by Roger Banks GW4WND, licenced since 1981. Roger can regularly be found operating VHF/UHF DX'er via tropo, E's, MS and EME operation on SSB, CW and Data Modes. http://www.thedxshop.com/index.htmlThe DX Shop Limited Dingle Cottage Churchstoke Montgomery Powys SY15 6TJ United Kingdom Sales/advice: 01588 620126 Overseas: +44 1588 620126 Fax: +44 (0)1588 620145 Email: esales@thedxshop.comSKYPE: roger_banks Our telephone lines are open 8:00AM until 6:00PM Monday to Friday, and 8:00AM to 12 Noon Saturday. === RF Parts (California, USA) International Orders http://www.rfparts.com/old_site/exportorder.html |
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eHam Forums / Mods And Repairs / Incandescent Lamp/Based LED Cross Reference
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on: March 27, 2013, 05:56:18 AM
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Dialight current focus is offering LED replacements for "based" incandescent lamps (bayonet, screw, bi-pin, wedge, etc.). They offer 5 standard colors: read, green, yellow, blue, and white. Some are offered in polarized configurations. Getting to Know LEDs, Applications and Solutions http://www.dialight.com/Assets/Application_Notes/Indication/Getting%20To%20Know%20LEDs.PDFIncandescent Lamp/Based LED Cross Reference http://www.dialight.com/Assets/Brochures_And_Catalogs/Indication/MBELCRFX001.pdfGlossary of Terms (LEDs, Incandescent Lamps, Indicaors) http://www.dialight.com/Assets/Application_Notes/Indication/Glossary%20of%20terms.pdfDialight Corporation 1501 Route 34 South Farmingdale, NJ 07727 USA Tel: (1) 732-919-3119 Fax: (1) 732-751-5778 http://www.dialight.com |
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eHam Forums / Boat Anchors / RE: Icom IC-730
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on: March 25, 2013, 11:43:52 AM
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I'm trying to locate a DC Plug and lead for this Txr in the UK.
The socket has 6 pins and I could be a Molex. Can anyone advise? NO, it is NOT a Molex connector. It is a Nylon DC connector mfg. in Eastern Asia for the Japanese "Big 3" amateur radio mfg. (Icom, Kenwood, Yaesu). Molex, Tyco/Amp, and Cinch are three major connector mfg. in USA. Two are HQ here in Chicago.The DC power connector you require is very COMMON (in amateur radio usage) from 1980s till recently. Your LOCAL Amateur Radio retail store STOCK this connector and DC power cable sets.Go introduce yourself, meet some new people ! In the United Kingdom, you have well known Amateur Radio dealers that have these in stock. You can walk-in (retail) or order via telephone. ML&S - Martin Lynch & Sons Ltd. Whitehart Associates, East House, 109 Worpole Way, London SW14 8TN http://www.hamradio.co.uk/Haydon Communications, South Ockendon, Essex RM15 4YA Tel: 01708 862524 http://www.haydon.info/Nevada Radio, Portsmouth, Hampshire http://www.nevadaradio.co.uk/about-usIcom UK Find your local dealer in UKhttp://www.icomuk.co.uk/Find_a_Local_Icom_DealerI was just given an ICOM 735 by the family of a SK. It is also missing the 13.8V cable and connector. It uses the same one as the 730. If I find anything I will post it here. OFF-THE-SHELF, Powerwerx (California, USA) always has in stock, bare connector or cable set. http://www.powerwerx.com/oem-connectors/ |
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