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12 KW CCS ON 160-15M....USING THE 3CX-6000A7..... PART 23
12 KW CCS ON 160-15M....USING THE 3CX-6000A7..... PART 23 Here, the 7.0 vac @ 80 amp CCS fil xfmr and the mating 4 amp, 240 vac variac is installed. Along with the pair of 100 amp CCS rated....'supercon connectors'. 4 ga wire from supercon connectors over to RF deck...where another pair of 100 amp connectors will be installed. The supercon 100 amp connectors use 5/16" studs on the back end. (The larger 250 amp version uses 1/2" studs They also come in a 50 amp version, using 1/4-28 studs......and also a 25 amp version, using 10-32 studs). The power supply is progressing slowly due to time constraints. Fil voltage will be measured at the cathode terminals....via a small RF choke in each leg. On new / rebuilt tubes, it's run at rated V for the 1st 200 hrs. Emission increases during the 1st 200 hrs, then levels off. After 200 hrs, the fil V is reduced by 10 %.... like down to 6.3 vac. https://www.youtube.com/watch?v=5l4bJ3MCfww
Started by Jim VE7RF @
SVHFS Presenters & Conference Update
Below is an update on the schedule of speakers and presentations for the Southeastern VHF Society Conference. The conference will be held at the Quality Inn at Exit #4 in Clarksville, TN April 4-5, 2025. This is an opportunity to meet other VHF+ enthusiasts, learn, exchange ideas, and have FUN. The $69 registration fee for the conference is required, and it includes a 1 year membership in the SVHFS. Details are here: https://svhfs.org/wp/2025-conference/. Advance registration is highly recommended as the hotel requires a head count in order to prepare the food for the event. There will be door prizes given away at the banquet on Saturday evening. Feel free to contact me via email if you have any questions: RobinK4IDC@.... Preliminary 2025 SVHFS Conference Schedule Friday 8:00 AM Registration 9:00 Charles Osborne -K4CSO 每 RF Zero - 30 min 9:30 Robin Midgett 每 K4IDC 每 RF Zero 2 Meter Beacon- 30 min 10:00 Bob Lear 每 W4ZST Power Dividers and Cable Loops 每 30 min 10:30 15 Minute Break 10:45 Mike Stipick 每 KC4RI 每 5.7 GHz SDR Transceiver - 45 min 11:30 Bill Pence 每 Grid Square Locator 每 30 min 12:00 PM Lunch - Steve and Sandra Kostro 每 Designing a Multi Band Transverter 1:15 2:00 Paul Wielozenski - K4PEW - VHF Nets 每 30 min 2:30 Ben Lowe 每 Rover Radiators 每 30 min 3:00 George Presley 每 10 GHz Beacon 每 30 min 4:00 Charles Osborne / Kent O* Dell 每 10GHz Antenna test Range - 30 min 5:00 Dinner 每On your own 7:00 Swap Fest and Hospitality Suite Saturday 9:00 AM Brian McCarthy 每 Lunar Rover Truck, 2.3GHz Amp 每 1 hour 10:00 Peter Van Horne 每 KA6U - Moon Bounce Rover 每 45 min 10:45 15 Minute Break 11:00 Chris Arthur - NV4B 每 45 min 12:00 PM Lunch - On your own 1:30 Larry Cagle - K4WLO 每 Meteor Scatter with MSK144 - 45 min 2:15 SVHFS Business Meeting 3:00 每 5:00 Rover Round Up and 10GHz Antenna Range 6:00 Social Hour- Hotel Bar 7:00 Dinner Banquet followed by the Door Prize Extravaganza! Thanks, Robin Midgett K4IDC
Started by Robin Midgett @
12 KW CCS ON 160-15M....USING THE 3CX-6000A7..... PART 22
12 KW CCS ON 160-15M....USING THE 3CX-6000A7..... PART 22 Here, the series bank of 2500 uf @ 450 vdc lytics is uniquely wired up, in it's final config. The ring terminal / spade lug is lopped off a sta-kon crimp connector, leaving just the barrel. The barrel is then slid over the round pins of the lytics. 16 ga silver / stranded / teflon wire is inserted into the barrel, along with the solid 16 ga (.052") lead of a 6 amp RVS connected diode, and also one end of the 100K @ 3 watt MOF EQ resistor. (1% Tolerance). The resistors all measure exactly 99,800 ohms. On paper, the V drop across each lytic should be identical. (375 vdc). Diss in each resistor is 1.4 watts. The function of the RVS connected diode across each cap, is in the unlikely event that if one leg of the main FWB rectifier assy failed shorted, you would end up with a condition whereby raw AC from the plate xfmr sec, would be pumped into the string of lytics, causing severe damage to them. The RVS connected diodes in this case, would conduct, bypassing the caps.... and taking out the HV fuse #2. (located between sec of plate xfmr and input to fwb). The replacement costs for those lytics is very expensive. (non issue if an oil cap was used) After crimping, the tops and bottoms of each barrel are then soldered. This makes for a 100% solid connection, both mechanically and electrically. Originally, those lytics were designed to be mounted to a PC board. The 3rd (un-used) pin was to make for a small tripod, for better support. In this application, the caps are inverted, and mounted with nylon capacitor clamps. The 330 cfm (filtered) intake air will 1st pass by the caps, before going into the planum of the RF deck. https://www.youtube.com/watch?v=wmoqie05B9s&t=2964s
Started by Jim VE7RF @
Drake L-7 : galvanometer lighting
No one answered my question. Maybe no one had the answer. I bought on www.AliExpress.com. (Donald is not going to be happy) BA9S 44 47 T11 T4W ba?onnette AC 6V LED These lamps fit perfectly as replacements. In the L-7 they are powered by 5 V AC. I checked that both alternations light up the diode. I chose the amber color, so it would look like the original lamps were filming. This may be useful to others -- F1AMM Fran?ois
Started by Fran?ois @
Original GM3SEK/G3SEK Tetrode Boards 4
Boards are 95% assembled and configured for 4-250A tubes. If you plan on using different tetrode tubes, you'll need to do the math outlined in the printed manual I'm including. Includes R14 wire-wound adjustable resistor, heatsinks & mounting hardware for TO220 transistors, off-board connectors, 500-ohm wire-wound pot, 5k 50W chassis mount resistor, remaining discrete components, and Stancor P-8671 117V 50-60hz/36v/1A transformer. I can provide photos of the boards. I am asking $550 + Shipping. Send your zip code, and I'll calculate the final cost. I prefer Zelle/Venmo and USPS money orders, too. No PayPal. All items are sold as-is with no returns. 73! Mark KA6WKE - DM34st Website: https://www.copperstate-it.com Youtube: https://www.youtube.com/ka6wke Amateur Radio: https://www.ka6wke.net LinkedIn: https://www.linkedin.com/in/markschoonover
Started by Mark Schoonover @ · Most recent @
Drake L-7 : galvanometer lighting
I'm going to bore you again with my L-7. The 4 lamps that light the two galvanometers are out of order (strange). They are powered by the 5 volts (alternating current) of the filaments of the 3-500Z. Have you replaced these fairly classic bayonet lamps? by LED lamps? -- F1AMM Fran?ois
Started by Fran?ois @
Grid bias 3-500Z 19
Hello Now that both of my 3-500Zs have been de-gassed, I have a new question. ﹞ In the L7 (Drake) the bias is at 0 volts ﹞ In the Kenwood TL-522 it is -7.5 V as shown in the following diagram We read a bit of everything http://amfone.net/Amforum/index.php?action=printpage;topic=46759.0 The objective is to put the L-7 into operation in SSB at medium power. -- F1AMM Fran?ois
Started by Fran?ois @ · Most recent @
Drake L-7 44
Hello I am in the process of putting a Drake L 7 amplifier back into operation. I was advised on this forum to bring the anodes of the 3-500Z to red to maintain the quality of the vacuum. After removing the screens to check the equipment and the filaments, I realize that once the screens are put back, there is no way to observe the anodes of the 3-500Z; everything is shielded (no window). How do you observe these anodes? -- F1AMM Fran?ois
Started by Fran?ois @ · Most recent @
Ameritron AL-1500 Relay 4
The output relay in my Ameritron AL-1500 needs to be changed. I checked with MFJ since they are still selling some Ameritron replacement parts, but no luck. From the user manual, this is "RLY1" and its Ameritron part number is 408-6139. This is a 3PDT, 10A, 12V DC through hole PCB mount relay. Two of the poles are used for RF switching and the third is used for another function. I've searched on Mouser, Digikey, Allied, Newark and E-bay websites without finding anything that might be a satisfactory replacement. Ideally, an original replacement part would be found. This would allay my concern about the contact materials which should be gold or gold plated for the two NC RF contacts to ensure good contact when receiving. Suggestions would be appreciated. 73 de Riki K7NJ
Started by Riki, K7NJ @ · Most recent @
SVHFS Conference 2025, Call for Papers & Presentations
Here's an update on the SVHFS 2025 Conference; Deadline for papers has been extended to March 17 Registration is open; details are in the attached file. Thanks, Robin Midgett K4IDC
Started by Robin Midgett @
Dilemma 16
Over the years I've collected parts to build an amplifier. Life got in the way during most those years but now I find myself with the time and ambition to build an amplifier for my boatanchors. As far as bottles are concerned I have a bunch of 813s a 3-400Z,. couple of 4-400s and of course the usual 811s, 807s, 6146s........Got plenty of iron for a power supply up to 3kv. Need some direction as to which way to go. I operate 40 thru 10. Have a soft spot for AM. (yes I'm old) but do CW and SSB. Finishing up a 350 watt modulator. OR should I forget all this stuff sell it and buy an amplifier. don
Started by kc1at @ · Most recent @
AL-82 Date of Manufacture 3
Hello, Can the vintage or date of manufacture be determined from the serial number on an Ameritron AL-82? Thanks and 73, Garry - K4OR
Started by Garry - K4OR @ · Most recent @
Sideband Engineers SB-2LA
This one is from 1965: https://www.eham.net/reviews/view-product?id=12175 A ham I know says his ant relay is stuck, its an open frame relay he says. Probably no parts for this one around anymore? -- Steve Hearns [ KA2PTE ] Technotronic Dimensions, VT [USA] WWW.TECHNOTRONIC-DIMENSIONS.COM E-Mail: Steve@...
Started by Technotronic Dimensions @
Update: ?Southeastern VHF Society 2025 Conference Announcement & Call For Papers #2MAmplifier
The timeline for submission of papers and presentations has been extended to March 17th.
Started by Robin Midgett @
Smoker contamination removal 25
Gonna try and detox an ACOM 1500 amp previously owned by a smoker ham, anyone ever have to remove the niccotine film before maybe with chemicals? Contact cleaner wont take it off, alcohol on a rag seems to dissolve it, so I may try that with small toothbrushes to get into the tight spots. I read someone once hung a smoker contaminated ham rigg from a wire in their garage and put cardboard under it, and soaked it inside and out with WD40, let it penetrate overnight and said it yielded good results. Not sure about that tho. -- Steve Hearns [ KA2PTE ] Technotronic Dimensions, VT [USA] WWW.TECHNOTRONIC-DIMENSIONS.COM E-Mail: Steve@...
Started by Technotronic Dimensions @ · Most recent @
Commander HF-2500 Plate Choke 4
Somebody who previously owned my Commander HF-2500 replaced the carbon resistors in the plate parasitic chokes with a different type of resistor. This worked fine on low frequencies 160M, 80M, and 40M. When I used the amplifier on 10M, it became very unstable, most likely with a parasitic oscillation and caused the plate blocking capacitor to explode and catch on fire. The main fuses blew, as well as the one on the board that contains the bias and control circuitry. After replacing these fuses and installing carbon resistors in the parasitic suppressors, I found that the amplifier would no longer work on 80M. Eventually, I discovered some discolored places on the plate RF choke where it had evidently arced through its insulation causing the needed 10M high impedance to shift. The choke was replaced with one I had from another Commander HF-2500 that has been a source of spare parts. While trying to do this, the windings (there's more than one - rather complex winding - some over the top of others) became loose, and I unsuccessfully spent several hours trying to get the windings back like they were and tight on the form they were wound on. Even though not satisfied with the replacement choke with loose and sloppy windings, I tried the amplifier on all the usual bands starting at 160M and up to 10M. It seems to work fine up through 15M, but the 10M band doesn't tune properly - most likely because the plate choke was still a problem. Does anybody have an original Commander HF-2500 plate choke that they would like to sell or know where I might find one? Another possibility is to substitute a different plate choke that works well in another amplifier with similar plate parameters. Probably the big challenge in using a different choke would be to mechanically fit it into the rather crowded place in the Commander. Another possibility would be to add a second plate RF choke with a high impedance on 10M in series with the other choke, but this still might be problematical due to the tendency of the big choke to break down as before. Suggestions, especially from anyone who has successfully used a different choke in the Commander, would be very much appreciated. 73, Riki K7NJ
Started by Riki, K7NJ @ · Most recent @
Dentron DTR-2000L info
Hi All, I have a DTR-2000L that I'm trying to bring back to life. It's the same one that I asked about last year. What I'd like is IF someone that has one of these amps, that's working, would you be willing to take some pics of the coil and cap section of the tank circuit so I can determine what I need to do to return it to stock. The tank coils have been soldered ALL OVER THE PLACE. All the leads going back to the band switch have been moved and I'm sure some genius tried to convert it to 11 meters. BTW, it DOES appear that is had a NEW socket installed in it and it's marked as such. I won't be convinced on that until I pull it apart and verify the ground connections at the socket. Anyway, if someone could be of some help, I would appreciate it Thanks!!! -- Kim Herron W8ZV w8zv@...
Started by Kim Herron @
Commander HF-2500 2
This is a real long shot. I have an old Commander HF-2500 which I love very much. It is Serial Number 186 and it conforms with the printed manual and schematic of June 1990. However, there is no diagram or separate drawing of the Meter Circuit Detail, as published in the later versions of the manual that one finds online. For instance the circuit published 6/16/95. The 1990 Meter Circuit Board does not conform to the later published diagram. Therefore, I am hoping that someone may have been here before me and has the the information that I'm seeking. That is, I'm looking for the diagram of the meter board and the wire colour code and description of the 12 connection points on the board. In particular, points 1 to 8 which relate to grid meter and plate/HV metering and the selector switch. I The Meter board is hard to get to, so I cut mine out to install meter dial LEDs and I extended the wires, so that it could be mre easily removed and serviced. I would dearly like to compare my board to a drawing of the correct era. Any help appreciated. 73 and thanks, Alek VK6APK.
Started by Alek Petkovic @ · Most recent @
Two tones test generator 14
Hello Do you have any recent experience of buying a generator of this type. Please send me references of such a product. Thank you -- F1AMM Fran?ois
Started by Fran?ois @ · Most recent @
?Southeastern VHF Society 2025 Conference Announcement & Call For Papers #2MAmplifier
? Southeastern VHF Society 2025 Conference Announcement & Call For Papers Quality Inn, 3095 Wilma Rudolph Blvd, Clarksville, TN 37040 April 4th and 5th, 2025 Papers and presentations are solicited on both the technical and operational aspects of VHF, UHF and Microwave weak signal amateur radio. Somesuggested areas of interest are: ? Transmitters, Receivers, Transverters ? RF Power Amplifiers, RF Low Noise Preamplifiers ? Antennas ? Construction Projects ? Test Equipment and Station Accessories ? Station Design and Construction ? Contesting, Roving, DX-peditions ? EME, Propagation (Sporadic E, Meteor Scatter, Troposphere Ducting, etc.) ? Digital Modes, Digital Signal Processing (DSP), Software Defined Radio ? (SDR) Amateur Satellites, Amateur Television In general papers and presentations on non-weak signal related topics such as FM repeaters and packet will not be accepted but exceptions may be made if the topic is related to weak signal. For example, a paper or presentation on the use of FM simplex in contests or on the use of APRS to track rovers during contests would be considered. Formats: All submissions for publication in the proceedings should be in Microsoft Word (.doc or .docx) formats. Submissions for presentation at the conference should be in Microsoft PowerPoint (.ppt or .pptx) format and delivered at the conference on a USB memory stick. Please understand that your PowerPoint Slide presentation will not be accepted to be published in the proceedings; only meaningful text will be published in the proceedings, not slides that need description for understanding. Paper: Size should be 81?2 x 11-inches. Margins: Top and sides should be 0.75 inches; bottom must be 1 inch. Font: You may choose your font, however, try and use standard fonts. The font should be clean and easy to read 12 pt. Layout: Either a one or two-column format. Page numbers: Do not include page numbers. Headers/Footers: Do not include Headers and/or Footers. Drawings: Drawings should be embedded in the files. Place them where you*d like them to appear. Photos: Color or black-and-white digital images if utilized should be embedded in text files. Place them where you*d like them to appear. Printing: We print what we receive. We do not copy edit (but will correct something if we notice it 每 or if you notice it and let us know). We try to make all papers somewhat uniform, but we do not rework each article. Page numbers are added as we prepare the files for our printer. The deadline for the submission of papers and presentations is February 15, 2025. Please indicate when you submit your paper or presentation if you plan to attend the conference and present your paper in person or if you are submitting solely for publication. Papers and presentations are being handled by Mike Stipick, KC4RI, and should be sent to: KCRI@.... Mike may be contacted at the same email address if you have any questions.
Started by Robin Midgett @
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