Re: [AMRadio] 75 Meters Long Already
In a message dated 11/26/06 3:27:46 PM, [EMAIL PROTECTED] writes: Have you guys in the N.E., East West coasts had the same lack of short skip on 75 after dark? Same thing here in SOCAL. Dennis D. W7QHO Glendale, CA __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] FS: HR Magazines, Raio-Electronics Books Literature
In a message dated 10/26/06 6:36:54 AM, [EMAIL PROTECTED] writes: GP-Series Transmitter section, excerpt from WWII-era publication “Aircraft Radio, Naval Air Technical Training Center, Ward Island, Corpus Christie, Texas”. Maybe 10 pages on the GP transmitters. $5 Don, I'll take this one. Dennis D. W7QHO Glendale, CA __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] dirt cheap chassis punch set
In a message dated 10/19/06 9:00:05 AM, [EMAIL PROTECTED] writes: Print the coupon picture below. http://www.harborfreight.com/cpi/emails/42/RetailB/images/1.jpg Cupon worked FB at Pasadena, CA store. They had a good pile of them in stock too. Dennis D. W7QHO Glendale, CA __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] dirt cheap chassis punch set
OK, see why these are selling cheap. The sizes listed on the outside of the package are not what's inside. Supposed to be 1/2, 3/4, 1 1 3/4 inches. More like 7/8, 1 1/16, 1 5/8 and 1 11/16. Also. something very starange with the smallest of the two drive bolts supplied. Still worth 12 bucks, I guess. Dennis D. W7QHO Glendale, CA * Previously: In a message dated 10/19/06 11:39:03 AM, W7QHO writes: Print the coupon picture below. http://www.harborfreight.com/cpi/emails/42/RetailB/images/1.jpg Cupon worked FB at Pasadena, CA store. They had a good pile of them in stock too. __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] AM on 3970?
All, The West Coast Military Collectors Net meets at 8:00 PM Pacific Time Saturday on 3983 kHz. Listen for us and please join in if propagation permits. Dennis D. W7QHO (NC) Glendale, CA __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] VHF AM Group
No regular activity here in the Los Angeles area. Another fellow and myself talked about getting something going but then he up and moved to Idaho. There will be at least a couple of old military rigs on 144.450 during our Nov. 4 MRCG FD in San Pedro. Did some hearability tests yesterday (Sep. 24) between Ft. MacArthur and other locations in the Palos Verdes Peninsula we use for this event. Used a pair of SR-42s for the test but will be running SCR-522, ARC-1, ARC-4, etc. stuff during the event. Dennis D. W7QHO Glendale, CA __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Filament Transformer for pair of 833A's
In a message dated 8/20/06 11:23:42 PM, [EMAIL PROTECTED] writes: My question was, are we paying $50 for it, because it was in a transmitter? Are we paying $50 for it, because it's rated for the same filament power as 833's? Or are we expected to pay $50 for it, simply because it's 'old'? Because $50 is the price the seller put on it. Doesn't seem so complicated to me.. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Just a refresher...
In a message dated 8/20/06 11:32:21 PM, [EMAIL PROTECTED] writes: I know Brian has said it, and said it (and said it some more)... maybe just one more time will help someone else understand. Been said enough several times over. Now, can we get on to something interesting here? Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Legal-Limit tuner advice....?
In a message dated 1/12/06 8:31:16 AM, [EMAIL PROTECTED] writes: On Wed, 11 Jan 2006, [EMAIL PROTECTED] wrote: Quick and dirty, just try grounding one side of your ladder-line at the input end and feeding the other side off the single ended output of your ATU and see what happens. SWR figures might be better (but could also be worse). John, Did you ever try this? If so, what were the results? Dennis D. W7QHO Glendale, CA
Re: [AMRadio] FS: NOS Transformers and More Miscellany
In a message dated 8/11/06 8:16:32 AM, [EMAIL PROTECTED] writes: NOS 24VCT 5A transformers. 12-0-12. 117VAC, 60cps input. Modern transformers made in Taiwan. 2.5 inches tall by 2.75 inches wide. Two mount holes are 3-11/16 apart. This is a currently shipping part from All Electronics as their part number TX-245 at a price of $19.50. My price is $5 each. 10 available. Buy several and get your money's worth out of a postal flat rate box. Don, I'll take 3 of these. Dennis DuVall, W7QHO 1524 Princes Dr. Glendale, CA 91207
Re: [AMRadio] The new FCC rules are here!
In a message dated 7/27/06 8:52:12 PM, [EMAIL PROTECTED] writes (in part): Dateline, Washington, DC The FCC today took what they described as an important new step to reduce QRM on amateur frequencies by setting standards for voice speeds. ABOUT TIME!!! Dennis D. W7QHO Glendale, CA
[AMRadio] Re: FREE! 400 Cycle MG set
Got it working. Offer still holds. Dennis D. W7QHO Glendale, CA
[AMRadio] FREE! 400 Cycle MG set
Ex USN unit. One HP 115v. 60 Hz drive motor, and the generator side is rated at 600 watts, 115 volts @ 400 Hz. Came up with a pair of these from an estate in the Valley a couple of years ago. I use one with my PRC-47. The other unit worked initially and then lost output. Don't know what the problem is but don't think it's serious. I checked the windings in the generator and all were OK but I didn't pursue the problem further because I had the second unit. Motor runs FB. Anyway, it's free for the hauling. Weighs about 150 lbs. Will deliver in LA area. ON IT'S WAY TO THE LANDFILL SHORTLY IF NO TAKERS. Dennis D. W7QHO Glendale, CA 818-240-7907
Re: [AMRadio] OUT SOURCE OUT OF COUNTRY TECH HELP
In a message dated 7/14/06 4:05:38 PM, [EMAIL PROTECTED] writes: Dell has gone down hill drastically... GO APPLE GUYS! Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Looking for BC-342N
In a message dated 7/11/06 11:58:55 AM, [EMAIL PROTECTED] writes: Also would be interested in knowing if anyone has a silk screen for the front panel already made as I suspect I will need some panel work done if I find one in my price range. The front panel on the N and other later models were not silk screened. Etching (?) process was used that left the panel labeling raised above the surrounding painted surface. Earlier versions used engraved front panels. Don't exactly when the change took place. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] FS: Tube, Boatanchor and Vintage Computer Literature, Also Raytheon QK422 Klystrons
In a message dated 6/27/06 5:45:54 PM, [EMAIL PROTECTED] writes: ARINC Research Corporation, Application Notes For Military Receiving Tubes, Supplement To MIL-HBK 211, June 30, 1959. “…goes beyond the handbook in dealing with various application problems which are commonly encountered in complex equipments.” Discusses circuit design and application data with an empahsis on reliability. 225 pages, comb-bound. Covers 6V miniature tubes and 5000-6000-series JAN tubes with charts and tables for each tube type. Amazing reference. $27 Don, I'll take this one is still available. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Question about ferrite rods
In a message dated 6/16/06 11:07:53 AM, [EMAIL PROTECTED] writes: I have often thought that a large remotely rotatable ferrite based loop on the roof or attic would be real nice for those difficult times. Bill, Give a small tunable loop a try. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] My comments (was REPLY BUTTON)
In a message dated 6/14/06 12:19:38 PM, [EMAIL PROTECTED] writes: I appreciate this list and got my DX-100 due to a for sale message on here! I seem to remember steering you on to this deal. SX-42 came with it. Ever get this setup on the air? Dennis D. W7QHO Glendale, CA
Re: [AMRadio] How the reply button works
In a message dated 6/11/06 4:09:01 PM, [EMAIL PROTECTED] writes: Everyone, please send your vote to list so we can all feel confident in the final decision. OK, apparently I cast the first vote (stone?). Again, I prefer TO THE PERSON. If I believe my response is of interest to the net (or anyone else's business) I'll distribute it accordingly. Not really a big deal to me either way, though. Most reflectors seem to go to the list as someone else noted. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] PA set up using ant analyzer
In a message dated 6/4/06 8:13:09 PM, [EMAIL PROTECTED] writes: Does it matter the type of tube, 833 or 592 r What's a 592 r tube? Can't find it in Fathauer or Sibley. See references to a 592 and a 592/3-200A3 but neither looks like a substitute for an 833. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] (2) 801As needed
In a message dated 5/31/06 2:08:08 PM, [EMAIL PROTECTED] writes: Anyone on the list have, or know of a source for a couple of 801As? I'm getting a BC-223 on the air and got everything but those tubes. Cash or willing to trade. Mark, NOS pair up on the e-place as we speak. See my earlier e-mail to you on getting a 223 on the air. Just curious, which TU's do you have. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] 10 Meters
Hearing OR, CO, AZ, OK TX out here 2000 - 2100 Z. All SSB, though, NOTHING up in the AM window. (Yes, I did call CQ on 29.0.) Dennis D. W7QHO Glendale, CA
Re: [AMRadio] 10 Meters
In a message dated 5/27/06 4:05:00 PM, [EMAIL PROTECTED] writes: Called CQ quite a few times between 2230 and 2300 today (Saturday). etc., etc. Not hearing anything on 10M out this way. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] BC-610 Modulation Transformer
In a message dated 5/27/06 2:36:10 PM, [EMAIL PROTECTED] writes: You've got it, John. That accurately describes the terminals on my BC-610D transformer, anyway. Larry, My copy of TM 11-280 (SCR-299) indicates the terminals as being marked B and P respectively for the B+ and Plate ends othe windings. Any markings on your unit? Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Ferroresonant transformer revisited
In a message dated 5/10/06 7:26:42 PM, [EMAIL PROTECTED] writes: I use a T-368 PTO as my main station vfo. I stabilised it by running the filaments off a regulated DC supply. Also use it to run mic preamp. Now have stable VFO and hum-free microphone preamp. I'm not sure why a small fraction of a percentage variation in filament voltage will cause such noticeable drift. Without the regulated filament voltage, neither the A4 nor the T-368 pto are stable enough to work 40m cw using a narrow filter. T-368's following the Basic model included a constant voltage xformer for the PTO filaments. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] 160 meters
Any suggestions as to where I am likely to get in on the most AM? Not sure where you're located, but in my experience: East Coast - 1955 kc Wed. evening (Gray Hair Net). Also 1885 kc Midwest/Chicago area - 1980/85/90/95 kc West Coast - 1925 Tues., Th. Sat., 8:00 - 9:00 PM. Also 1885 occasionally. 1885 kc used to be the traditional AM hangout freq. but use seems intermittent nowadays. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] DX-60 Modulators
In a message dated 4/14/06 9:05:49 AM, [EMAIL PROTECTED] writes: Will sell set for 50.00 plus shipping. Thanks, Byron. Byron, I'll take a set. Dennis D. W7QHO Glendale, CA
[AMRadio] MRCG 2006
Military Radio Collectors Group 2006 Meeting May 5 – 6, Camp San Luis Obispo, California The eleventh annual meeting of the Military Radio Collectors Group will be held at the NCO Club, Camp San Luis Obispo, California from May 5 to May 6, 2006. Events will formally begin at 0800 Friday morning, but early arrivals are welcome Thursday afternoon, May 4.Registration will be open at 1800 Thursday evening. Those planning to attend are requested to contact Lynn Fielding at [EMAIL PROTECTED] or (310) 533 – 8627. Those entering the facility must show automobile registration, proof of insurance, and identification at the front gate! See http://www.calguard.ca.gov/cslo/Veh_Pass_rules.htm for more information. Secured areas for equipment operation and display will be available inside the Club and there is ample room on the surrounding grounds and the campground to accommodate outdoor activities. Friday will be devoted to equipment setup and display, operating events, technical presentations, and informal gatherings in and around the campground. Special activities may include fox hunts on 6 meters and/or 75 meters. The swap meet will be held from 0730 – 1100 on Saturday morning with a barbecue following at noon ( advance sign up required, see below). Coffee, tea, water and soft drinks will be available during the event. Continental breakfast items and juice will be available on Friday and Saturday mornings Lunch on Friday, dinner on Friday, and a lunch on Saturday will also be available with advance sign up. Contact Lynn Fielding at [EMAIL PROTECTED] for food details. Tent and car camping will be available on site adjacent to the event. Full RV hookups are available for $16 and electricity and water only are available for $14 per night. Billeting is available at the camp on a space available basis for $23 per person per night. VIP quarters are $25.75 per night. Hookup and billeting reservations can be made by calling (805) 594 - 6500. There are no admission charges for this event, but a fair share contribution of $10.00 is requested from each participant to defray event costs. Points of Contact Lynn Fielding, KE6JZD (Registration and Logistics) [EMAIL PROTECTED] (310) 533 – 8627 Bart Rowlett, WB6HQK [EMAIL PROTECTED] (310) 533 – 8627 Other Useful Information http://visitslo.com/ http://www.discoverourtown.com/TownPage.php?Town=2156Cat=Organizations http://www.calguard.ca.gov/CAAG-MS/ http://www.syzen.com/milradio/ Directions: From the 101, take highway 1 west, toward Morro Bay. Camp San Luis Obispo is five miles west of San Luis Obispo. Turn south (left) from Highway 1 to enter at the main gate. The NCO Club and the campground is on the west side of the camp. Directional signs will be posted along the route from the main gate to the NCO Club.
Re: [AMRadio] possible interference coming up
In a message dated 4/4/06 6:03:48 PM, [EMAIL PROTECTED] writes: On Tue, 4 Apr 2006, [EMAIL PROTECTED] wrote: Maybe, maybe not, but it's not your problem. If his audio equipment is responding to your transmissions then HIS equipment is malfunctioning, not yours. Dennis, I respectfully disagree - in a lot of cases, taking a pro-active tack can mean the difference between 'happy hamming' and bad feelings, lawsuits and neighborhood retaliation. John, I stand by my original statement. Now, whether or not to help the other guy out is another matter and would depend on the surrounding circumstances, most importantly the attitude of the complaining party. In the past I've usually tried the proactive approach as you call it but with little success, sorry to say. The usual response I've encountered is something along the line of ...my (expensive) stuff was working just fine until you came along, so shut your junk off now! followed by out-and-out refusals to let me anywhere close to their TV, telephone, Hi Fi, etc. I even offered several interference free telephones to one guy who refused to even give them a try (I don't want your damm phones!). If the guy's wife is your wife's best friend ya gotta play nice, of course. Ditto if he's your landlord, boss, your minister, etc., but I personally wouldn't touch anyone's expensive music and/or entertainment systems. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Re: Modulator design needed
In a message dated 3/28/06 1:47:38 PM, [EMAIL PROTECTED] writes: (1) Change screen grid voltage to ~450V, Wow, that's pretty hot for an 807. What kind of screen dissapation numbers are you seeing with this? Dennis D. W7QHO Glendale, CA
Re: [AMRadio] RE: Modulator design needed
In a message dated 3/27/06 4:48:02 PM, [EMAIL PROTECTED] writes: The 807's in the Viking and DX-100 run in AB2. I know the VII manual sez AB2 but no way with that triode connected 6AU6 driver (AB1.25 maybe). A popular mod was to replace with a parallel connected 12AU7 which doesn't give enough kick either and the stock driver transformer won't handle AB2 power levels in any case. The stock VII audio system can provide just enough output for good sounding 100% modulation with a hot pair of 807s and careful adjustment. Regulating the screens at 300 volts will help a lot too. Don't know what Heath did about the problem, but note that DX-100s (pair of 1625s) usually sound quite good on the air. I modified my VII for proper AB2 operation with a 6AQ5 driver, 5W driver xformer, negative feedback, and regulated screen and bias supplies. Works FB but a non-trivial undertaking. Swapped a pair of EL-34s for the 807s in another VII; regulated the screens but left the rest of the audio string original. Worked just as well as the AB2 mod and MUCH easier to do. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Amplifier to use with my DX-60
In a message dated 3/19/06 10:01:34 AM, [EMAIL PROTECTED] writes: I would appreciate a copy of this info. Healthfully yours, DON W4BWS Don, Are you good in QRZ? Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Amplifier to use with my DX-60
In a message dated 3/18/06 8:48:57 PM, [EMAIL PROTECTED] writes: I would be interested in that Dennis. TNX. Mod-U-Lator, Mike(y) W3SLK Mike, Are you good in QRZ? Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Amplifier to use with my DX-60
In a message dated 3/19/06 12:19:58 PM, [EMAIL PROTECTED] writes: The 1956 QST gives you so much more for 25 cents extra. You get vintage yellowed pages, a nest of Silverfish, and Wayne Green's Never Say Die soap box editorial... :-) Jim --- W5OMR/Geoff [EMAIL PROTECTED] wrote: Jim Candela wrote: Check out Ebay, a copy of CQ magazine, Article: June 1956, Mobile Reference-shift Modulator, Item number: 5834903572, cost $4.00 buy it now back issues of ER are $3.75 Just checked my CQ collection and discovered I have the June 56 issue. The Mobile Reference Shift article was written by Dale Hileman, K6DDV, the author of the earlier Radio and TV News piece. Both articles cover essentially the same ground. For those who requested more information on the scheme I will include a copy of the CQ article along with my later discussion as published in ER. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Amplifier to use with my DX-60
In a message dated 3/18/06 9:41:29 AM, [EMAIL PROTECTED] writes: Actually, I'm a subscriber and have that issue. How did I miss remembering that when I got the DX-60? Thanks, Harry, KT4AE Maryville, Tennessee [EMAIL PROTECTED] wrote: Harry, In the January, 2004 issue of Electric Radio, there is an article on the DX-60... Also, see ER# 133 (May 2000) and 140 (Jan. 2001) Dennis D. W7QHO Glendale, CA
Fwd: [AMRadio] Amplifier to use with my DX-60
Re: [AMRadio] FS: AC-1, Homebrew, Command Sets, Simpson, MFJ, Pomona, 1625 Tubes, More
Don, I need one each of the 7 and 9 pin socket savers. How much PP to 91207? Dennis D. W7QHO Glendale, CA
Re: [AMRadio] 6BG6 ad
Could be legit. The GA tubes he he's selling sure don't look like the run-of-the-mill 6BG6's. His test not vety scientific but ordinary 6L6, 6BG6, 807, etc. examples would get red in the face under such treatment. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] W4CJL's Taylor Super Modulation
In a message dated 2/24/06 9:16:23 PM, [EMAIL PROTECTED] writes: There is a circuit of sorts in ER Number 179 with a story about Hoisy not long after his death.I will see if I can send you a copy. Are you sure about the issue #. I don't find the story in my ER 179 (Ap[ril 2004). Dennis D. W7QHO Glendale, CA
Re: [AMRadio] W4CJL's Taylor Super Modulation
In a message dated 2/20/06 2:19:28 PM, [EMAIL PROTECTED] writes: Does anyone know if the articles that, Don Hoisington W4CJL, wrote about Taylor Super Modulation still exist today ? Don't have any information on the W4KCL articles, but for the best analysis of the scheme and a critique of the wild claims made for it see: Supermodulation -- An Evaluation and Explanation Oswald G. Villard, Jr., W6QYT QST for December 1950 Villard was a Stanford Engineering professor and trustee of W6YX, the university's club station. Other references: Radio News -- Sept. 1948; June 1949; Feb. 1950; May 1950; July 1950 R. ETaylor, Modulation System, U. S. Patent No. 2,282,347, May, 1942 Dennis D. W7QHO Glendale, CA
Re: [AMRadio] W4CJL's Taylor Super Modulation (more)
Also, see ER #105, January 1998. In a lead-in to the article, the editor of the mag (then N6CSW) makes reference to Don Hoisey Hoisington, W4CJL and future articles on Supermodulation. However, a search of the ER index reveals no further mention of the subject. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Re: [FLBOATANCHORS] Replacing sweep tubes with 6146s
In a message dated 2/19/06 12:05:01 AM, [EMAIL PROTECTED] writes: Sweep tubes are more expensive and don't last as long. 6146's are rugged. They've been through the fire before, and they'll stand a whole lot more. I'm still using the original 6JS6C pair in my Yaesu FT-101B. Bought the rig in 1975 and have operated it regularly ever since, mobile, fixed, SSB and AM. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Replacing sweep tubes with 6146s
In a message dated 2/18/06 1:26:00 PM, [EMAIL PROTECTED] writes: I seem to remember a few years back an article on converting the finals in a FT-101* to 6146s. Seems like a good idea now since a 6KD6 sweep tube cost a lot more than a 6146. Lots of 6KD6s on the e-place. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Re: AM Transmitter Advice??
Dennis D. W7QHO Glendale, CA
Re: [AMRadio] AM Transmitter Advice??
Linears for AM -- here we go again for at least the third time in the past 12 months. Basic considerations: 1. Under carrier only conditions a correctly designed and adjusted linear amplifier will be operating at about 33% efficiency. So, with a pair of 813's the math works out to 125 watts of carrier, obviously not worth the effort if you're starting off with a 100 W carrier exciter. 2. The linear must be initially tuned up at the peak RF output value which, in turn, requires that the exciter (or some other source) must be capable of providing the input necessary to do this. Typically, his would be 4 times the carrier value but expect to hear a lot more on this from the asymmetrical speech waveform crowd. 3. Real AM can only come from a plate modulated class C PA in the view of certain members of this community. At the same time, big mod iron is expensive and hard to find. Also, for a legal max rig the wall plug efficiency of high level and linear is not that much different in the final analysis. Bottom line -- If you're going to build a linear do it right and go for a pair of 4-400's, single 4-1000A, 3-1000Z or one of the big Russian tubes I've seen on eBay recently. I use my HB 3-1000Z amp on both SSB and AM, BTW. Works FB. Good luck with the project. Dennis D. W7QHO Glendale, CA *** Original message dated 1/30/06 12:08:03 PM, [EMAIL PROTECTED] writes (in part): My friend, KR1S (Jim Kearman) is designing an AM transceiver, for me. We plan for this to be a solid-state unit that will deliver about 100 watts out. It will be single band (75 meters) and I have been considering using that to feed a homebrew linear. I have the makings of a 2 x 813 amp thanks to my and Jim's hamfesting efforts. So far, we have been reading and kicking around ideas. It seems that with the derating of the amp to handle the continuous carrier, etc.. may be more trouble than it is worth.
Re: [AMRadio] AM Transmitter Advice??
Gary, Thanks. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Heath SB-30X series AM filter
In a message dated 1/27/06 10:45:49 PM, [EMAIL PROTECTED] writes: Can anyone look up the part number of the AM filter for the SB-300/301/303 receivers? Steve, My SB-300 Assembly Manual lists two different units, #404-201 and 404-M201P22. (3.75 kc bandwidth) Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Re: Your comments abou t AM
In a message dated 1/15/06 8:26:57 PM, [EMAIL PROTECTED] writes: Mike Mertel, K7IR, developed what I believe is one the most innovative new antenna ideas in years if not in decades. The U.S. Patenet office apparently agrees and awarded him a patent for it. Mike is an Electrical Engineer but I don't believe he worked in the antenna field before starting SteppIR. That was born from his interest in ham radio. www.steppir.com Clever application of long understood and applied techniques. Original and innovative but hardly a state of the art advance. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Negative Loading circuits - good, bad, or ?
In a message dated 1/11/06 5:26:15 AM, [EMAIL PROTECTED] writes: The 3 diode circuit is supposed to prevent the plate voltage from going to zero. I use variacs on the power supply so I can set the point at which the circuit starts working, and no matter if I set it to 95, 90, or 85% I get splatter if the audio would exceed 100% negative, so the circuit seems to do no good. Brett, What circuit are you using? The ones I referenced don't call for variacs or auxiliary power supplies. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] I'm not an antenna expert
In a message dated 1/11/06 9:18:50 AM, [EMAIL PROTECTED] writes: I'm afraid of what I'm doing to the tuner/transmitter at that amount of reflected power. John, What kind of a tuner are you using and where are you measuring the SWR? Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Millen High Voltage Connectors
In a message dated 1/10/06 11:37:54 AM, [EMAIL PROTECTED] writes: If you over tighten the millen connectors they will crack the shell of the chassis part pretty easily. You may not realize they have cracked. This can be a leakage point. Yep, they sure will. For HV I like to use a ceramic feed through insulator covered by a removable housing to prevent accidental contact with the exposed screw stud. The Navy SRT-14/15/16 transmitters used ceramic plate caps (807 size) on the cable ends and ceramic feed throughs with appropriately sized brass mating lugs on the chassis side for HV connections. Clever solution. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Negative Loading circuits - good, bad, or ?
In a message dated 1/10/06 6:37:54 AM, [EMAIL PROTECTED] writes: I have used the 3 diode, power supply (variac) and load resistor setup on various rigs, the first one was the pair of 813's modulated by a pair of 4x150 (4cx250b) tubes in AB1. The circuit worked very well on the mod monitor and scope, and I could get ungodly amounts of positive modulation. Like 2500 to 3000 watts pep out of a 600 watt carrier, without any audible distortion I've had good results with the three diode circuit too. Earliest reference to the scheme I can find is in QST, October 1956 using 866 rectifiers. Covered again in ER #3, July 1989, this time with solid state diodes. More simple schemes can also give some useful benefit, ex., using a weak tube on the side of a P-P modulator circuit that conducts on the negative half of the audio cycle. Other cheap and dirty tricks include lowering the screen voltage on the same side or inserting a resistor in series with the plate. Can end up sounding bloody awful, though, if not done carefully and with restraint. I suspect the high voltage brick diodes I use have some sort of problem, switching speed? that caused very bad splatter when I would exceed 100% neg modulation. I saw no signs of it on the scope or mod monitor, but it showed up on the spectrum analyzer. Don't believe the type of diodes used would have any significant effect on this. Splatter is generated in the PA tank circuit when plate voltage is suddenly cut off on the audio negative half cycle. Same splatter would be produced if the PA was being fed straight off the secondary of the mod transformer. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] VFO for 20V-3
Let me cast a vote for the Globe 755(*). Built in PS and high output. Uncommon, though. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Valiant and Loop progress
In a message dated 12/6/05 6:44:29 AM, [EMAIL PROTECTED] writes: The 40 meter antenna works great, and I suppose I don't need to do anything with it, but fitting an 80 meter antenna in the space, without it being right over the house is the problem. What's wrong with an antenna strung over the house? I've been doing that here for years running legal limit AM and SSB with no problems. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Coast to Coast AM
In a message dated 12/5/05 9:16:30 AM, [EMAIL PROTECTED] writes: This is shaping up as a nice winter radio season and I hope others out west will give a listen to the easterners as we try to make the toss. Paul, Will be listening for you guys. Heard Tim here the other night +20 on 3880. K1JJ strong also. The long condx have been playing hob with our local nets, though. Cheers, Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Loop antenna feed question
John, Hmmm 450 loop at 5'. Feedpoint impedance would vary all over the place depending on frequency. Do you transmitting on this setup, and if so, are you using some kind of an antenna tuner, balanced output or single ended, how long is the feedline, and what frequencies do you intend to use? In any case, can't see that fanning out at the feedpoint would be necessary or useful. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Dumber than a rock question . .
In a message dated 11/13/05 10:38:49 AM, [EMAIL PROTECTED] writes: So, what the hell do I do with it? Wrap some wire around the protruding pins and solder it? That's the way I do it. Don't use perfboard, much though. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] receiver performance nd tube microphonics
In a message dated 10/31/05 10:48:49 AM, [EMAIL PROTECTED] writes: An audiophile friend gave me some tubes that he couldn't use in his preamp because they exhibited microphonics. Is it possible to use them in rf and if stages without degrading performance in a receiver? Try them and give us a report. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] ARRL handbook wanted, circa 1975
In a message dated 10/28/05 4:42:48 PM, [EMAIL PROTECTED] writes: The old ARRL handbooks are listed on eBay all the time. I have a collection from 1954 to 1981. Every 4 or 55 years is close enough to get most coverage. For good tube stuff recommend earlier than 1975, say 50's to early 60's. Orr's Radio Handbooks are great too as has already been mentioned. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] BC-610 down=up
In a message dated 10/26/05 1:59:40 PM, [EMAIL PROTECTED] writes: As to folks ideas as to what constitutes a long wire, THE manual AND the tuning cards for the BC-610 are VERY specific about the 44 ft for 80, 40, 20 mtr bands, AND is very specific about the 77ft for 160 mtrs The BC-939 is used EITHER for a 25ft vertical whip, or the above mentioned wire lengths. When using the wire lengths as stated in the manual and tuning cards, you MUST place the switch on the fron to the Long Wire position. The Army can call a 44 or 77 ft end fed wire antenna anything they want. The point, though, which I trust by now has been more than adequately made, it not to expect a stock BC-939 to work with the long wires most commonly used by hams and described in ham literature. As I said before, I agree that the 939 works fine with the antennas for which it was designed. In the past I owned the gray painted version of the device which came with my T368s. Full of nice components and very well made but wouldn't match any of the antennas I had in use at the time. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] BC-610 down=up
In a message dated 10/25/05 8:18:51 PM, [EMAIL PROTECTED] writes: Actually, The BC-939 (*) handles an end fed long wire, the recommended length for 2 - 18 Mhz is 44 feet. That number changes to 77 feet for 160 meters and works quite well. Actually, a 44 (or 77) ft antenna is not a very long wire even at 18 MHz. The term is usually used to describe wires measured in wavelengths as opposed to feet and inches, see various ARRL and other antenna books. Agree the BC-939 works well when used with the short antennas for which it was designed. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] High level modulation of tetrodes
In a message dated 9/27/05 6:11:03 PM, [EMAIL PROTECTED] writes: One fix would be to have a separate winding on the modulation XFMR and a fixed screen supply. This scenario means hard to find parts and complex circuits. The military ART-13 does this (813 modulated by a pair of 811s). Special transformer for sure, but the circuitry is otherwise simple and straightforward. Works great. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Pi-Net vs Link Couple
In a message dated 9/22/05 7:30:13 PM, [EMAIL PROTECTED] writes: that's interesting, Darrell... a reactor in the screen supply. Are you capacitivly coupling it, as well? No, that can't be - the screens need to be DC voltage. However, the choke effectivly kills any stray capacitances... A choke in series with the screen supply exhibits a high impedance at audio frequencies and allows the screen to self modulate. The technique has been around for a long time. A screen dropping resistor of sufficient size will provide the same effect. The military T-368 does this with an 80K screen dropping resistor off the 2500 volt HV supply and applies modulation to the plate of the 4-400 PA only. The same technique was applied in the T-195 (4X150D PA, 1KV plate supply). Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Re:Balanced Line Antenna Tuner
In a message dated 9/22/05 9:19:29 AM, [EMAIL PROTECTED] writes: I want to construct a balanced line antenna tuner to cover 160-10 meters, does any one have any good ideas on one, and where a diagram can be obtained. A multitude of circuits and thousands of pages of description, theory and discussion can be found in the various published handbooks and antenna manuals (ARRL, Editors and Engineers, etc.) from the 1930s up to the present time. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] info wanted on 4-400 linear amplifier
In a message dated 8/3/05 8:08:07 PM, [EMAIL PROTECTED] writes: The 1962 ARRL handbook has a single 4-400A amplifier, which I think is the original question Grid driven circuit, dual mode, AB1 and class C. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] info wanted on 4-400 linear amplifier
Ed, I would go for a grounded grid circuit. As Jim pointed out, 25 watts too much for grid driven AB1 or AB2. Don't have an exact circuit, but the1983 Handbook describes an amp using a pair of 4-400s running GG. Am sure it could be adapted to a single tube, or maybe you'd consider running a pair. I can copy the article for you. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Speaker
In a message dated 7/29/05 4:12:42 PM, [EMAIL PROTECTED] writes: Anyways was wandering what some of you guys are useing that are not useing matching speakers for there receivers. Also the Hammarlund calls for 4 ohm speaker and was wandering if the audio fidelty would still be OK useing an 8 ohm speaker of some sort? Herb, Well, I use a pair of Hammerlund speakers with my 51J4 and R390A. Also, a cheap Hi-fi speaker with my AR-88 and a Hallicrafters R-42 with my HQ-180. Other combinations as required. Four, 8, 16 ohms speaker/reciever impedances -- mix them all up and I, at least, can't tell any difference (am sure there will be some comment on this). Impedance matching does become an issue, though, with the military stuff which usually has 600 ohm outputs (my R390A audio has been modified for 8 ohms). Some of the old Hallicrafters sets had 2000 and 5000 ohm outputs the these require a matching transformer which was included in Hallicrafters speakers of the period. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] power ratings
Didn't this subject get beat to death back in January of this year? Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Heath SB Problem!
In a message dated 7/7/05 3:22:37 PM, [EMAIL PROTECTED] writes: Is anyone here familiar with the LMO drive on a Heath SB unit? BOB, I've been into the one on my SB-300. What's the problem/question? Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Matchbox Melts Down IC-735 ??
In a message dated 6/23/05 10:49:50 AM, [EMAIL PROTECTED] writes: Since you sold this thing on Ebay, whether you are right or wrong, your feedback may reflect your next step. Think carefully before proceeding. I dunno, one or two negative feedback's really a problem? Also, the seller gets the last word.. Dennis D. Glendale, CA
Re: [AMRadio] roundtable ettiquette
Grant, NQ5T, got it right. I would only add DON'T SCREW UP THE ROTATION! Write down a list of participants, keep it current as people check in and out and, above all, keep track of who passes the turn to you and who gets it next, i.e., stay in the game. Dennis D. W7QHO Glendale, CA In a message dated 6/23/05 6:01:56 PM, [EMAIL PROTECTED] writes: 1. Find someplace besides right smack dab on top of the existing round table to tune up. 2. Wait for someone to turn it to the next person in the rotation and just throw out your call. Break your call works, too. AM'ers generally leave a space between transmissions just for this purpose. If it's a more VOX-like exchange in progress, wait for a break and then announce yourself. Virtually all AM QSO's welcome anyone that happens by. 3. Leaving is about the same. Let people know you're going, that this will be your last transmission, etc. Don't just vanish. If you have to leave out of turn, use that space between transmissions to jump in quickly and let folks know you're going, then pass it to the person that was next in the rotation. 4. The bigger the group, the shorter your transmissions ought to get. There's nothing worse than a roundtable of 6-8 or more people all making long old buzzard transmissions -- it can be an hour (or longer) before you get to open your mouth again :-) What else? -- I don't know --- leave the bodily noises outside the radio room, and remember that you probably have a bigger general audience on AM than you would on sidband. If I'm working in the room but not participating I'd MUCH rather listen to an interesting AM QSO than the other stuff ... Grant/NQ5T Dennis D. W7QHO Glendale, CA
Re: [AMRadio] FS: Complete AM station...Pick-up only
Ed, Sorry to hear about your health problems. Have forwarded your message on to a couple of guys who might be interested. 73, Dennis D. W7QHO Glendale, CA
Re: [AMRadio] SSB AM revisited
In a message dated 3/17/05 4:04:03 PM, [EMAIL PROTECTED] writes (in part): The only way SSB AM can be destortion free is to run a vely low percentage of modulation, or insert additional carrier (the BFO). Ah, so... wondered about that. Ran a Harris 301/302 a while ago which in the AM mode adds a carrier to it's normal USB output. Observed that to sound good it had to be adjusted so that on the scope it looked like DSB AM modulated about 50%. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] mike
In a message dated 3/15/05 9:31:31 AM, [EMAIL PROTECTED] writes: Which means that my Electro-Voice 729 is a candidate which is already on my shelf...sparkling since I polished all that cast metal to high sheen. Steve, Your EV 729 should work fine. I would add a grid leak resistor, though. Anything 1 to 10 megs FB. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] FS: dynamotors
In a message dated 3/14/05 12:42:44 PM, [EMAIL PROTECTED] writes: I have a friend that wants to sell a couple of dynamotors. We are trying to identify them. #1 is type 3451, SS392A. #2 is type 51S1, SS439. Are these numbers enough to identify them ? Thanks. Ed, No, not really. Need Voltage and current in, and voltage and current out specifications. Also, look for identifying nomenclature beginning with DY, DM or PE. EX, DM-28-A, PE-103, etc. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] BC-610 Xtal Holder
In a message dated 3/6/05 11:36:09 AM, [EMAIL PROTECTED] writes: My question would be Does the FT-243 have tha ability to take the current/power that the FT-171-B xtals are designed for? Open up some of the later FT-171-B holders any you'll find an FT-243 size xtal inside. On the question of a 243 to 171 adapter, come on, guys, simple job to make one up. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] anyone for qrp am?
Back in the 90s there was a flurry of QRP AM activity in the Northeast. Known as PW (for P*** Weak)and included award certificates and nets. Max carrier level was 10 watts with a lower power sub-class. Brain child of K1JJ as I remember. I ran a 9 watt rig , 6AV5 PA modulated by a pair of 6AV5s with a 3-diode ultramod circuit running 200% positive modulation peaks. Had real punch! Interest died out after a year or so as I recall. Condx permitting, we military collectors run QRP AM regularly with our GRC-9, BC-654, BC- 1306, WS-19, etc. equipment. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] anyone for qrp am?
In a message dated 3/6/05 1:40:13 PM, [EMAIL PROTECTED] writes: I, also,would like to build a QRP AM rig. I have the 6L6's and 1625's. What I need is a modulation trandformer. Any suggestions, anyone? Thanks. For a plate modulator that works great and does not require a hard-to-find transformer try the circuit described by Dale Hileman in the April 1955 issue of Radio and Television news. Heising circuit with a clever bias shifting scheme included. Hileman called it a Reference Shift modulator. Circuit revisited in ER #91, November 1996 with some updates for using several popular sweep tubes in place of the 807 originally employed by Hileman. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] anyone for qrp am?
In a message dated 3/6/05 3:02:36 PM, [EMAIL PROTECTED] writes: Another alternative is series modulation. This has efficiency issues using a class A series modulator, but for low power AM this might be the ticket. At the following link are two circuits that I found somewhere, and am just passing them on. I never tried them. Regards, Jim WD5JKO http://pages.prodigy.net/jcandela/Modulator/ Essentially a form of grid modulation, see ARRL Handbook 1954 page 250 for a version using a 6SL7 and a 6Y6. I've heard these on the air sounding very good. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Ground(Or Lack Of)?
In a message dated 2/15/05 3:06:15 PM, [EMAIL PROTECTED] writes: Back to my 4th floor apartment problem. This building has plastic plumbing(which seems to leak at tleat once a month). This morning I pulled the plate off one of the wall plugs. The building has plastic conduit also. So the only ground is the third wire and who knows where or how it runs. The antenna will be made to a full 40M dipole. What kind of problems should I expect from the crappy ground? Bob, Entirely possible. I operated very successfully out of a 5th floor room in Germany back in the 1970s using a 400 ft end fed long wire. That high up (4th floor) your RF ground situation would be problematical regardless of the type of plumbing and/or electrical conduit used. Using a balanced antenna like you are, you shouldn't have RF in the shack problems but if you do, hang a quarter wave wire out the window connected to your xmitter chassis. You may need one of these stubs for each band you work. Your biggest problem, though, will be staying legal in regard to lightening protection. Local codes would likely require installation a solid grounding system for your antenna which you would have to clear with your landlord (and pay for yourself).If you want to bootleg it (which countless hams including myself have done) I would recommend making provision for disconnecting the antenna lead-in and getting it entirely outside the building when an electrical storm threatened. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Physical Reality of Sidebands
Sounds to me like the old question as to whether or not a tree falling in a forest makes a crashing sound if there is no one around to hear it. In answering such a question one has to draw a distinction as to whether sound exists only as the reaction of the human auditory system to pressure waves in the conducting medium (air in this case) or, do these pressure waves themselves constitute sound. Don seems to be saying sidebands exist only exist as a physical reality when apprehended by a human observer through the reactions of some kind of instrumentation (narrow receiver, etc.).Seems like a philosophical rather than an engineering issue to me. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] AM Amps
In a message dated 1/13/05 1:50:20 PM, [EMAIL PROTECTED] writes: How do you reduce the drive for AM? I take it that is how you operate CW? 73 Gary K4FMX James M. Walker wrote: Hum, 4-1000A G.G. amplifier, 3000 VDC plate, 700 MA Plate I, 500 MA Grid I, with 125 Watts out of DX-100 running apprx 2100 W input and dissipating 670 watts plate = approximately 1430 watts output! While the carrier level into 50 ohm dummy load is 1400 watts measured and a really NICE orange glow! This is with a 200 cfm blower, air system socket and chimney. Jim WB2FCN Good question. If I remember correctly, this thread originally started around the question of reducing the output of an AM transmitter to a level appropriate for driving a linear amplifier. Practically speaking, the process of setting up a linear amplifier for AM is complicated by the requirement that the amp be first adjusted for operation at the peak power level expected to be encountered which, in turn requires an RF drive source capable of providing this. This creates a problem if a small rig like a Ranger or an Elmac AF-68 is used, neither of which is capable of providing sufficient CW power to properly tune up the amplifier (presuming GG 3-1000Z, pair of 3-500Zs or equivalent here). When I first ran my HB 3-1000Z with an AF-68 some years ago, I would tune up the amp. using my Cubic Astro 103 which can provide any value of CW 0 - 100W. Worked just fine but switching rigs in and out was somewhat of a pain. I have an Apache and a Viking II here but have never looked into a modification to switch between the required tune and AM power levels (i.e., reduce plate and/or screen voltage or whatever).These days I mostly use a T-368 for high power, but on occasion I drive the linear with a little Kenwood TS-50 which very conveniently cuts the carrier level back automatically when switching from CW to AM. I've considered building up a screen or suppressor modulated exciter specifically for use with the linear. Grid modulated rigs, of course, have to be tuned up just like a linear, i.e., loaded and tuned to the CW level and then cut back to 1/4 of this for talking, thus also providing the tune-up and operate drive values required by the linear. Finally, however, it is possible to tune up a big linear with a small rig like a Ranger or Elmac. The technique involves use of a loud, verbal utterance containing a long string of repetitive voice peaks and tuning the linear to maximize the output amplitude of these. Northeastern hams will remember the YYYEII tune-up wail frequently used by one well know AMer. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] AM Amps
In a message dated 1/10/05 9:12:45 PM, [EMAIL PROTECTED] writes: Kinda Sorta. Depends on the quality of the transmitter. If he reduces the carrier output power of the Ranger, then the audio output power will rise, because there won't be as much final current flowing through the secondary of the modulation transformer. Depending on the impedance match of the final to the modulator through the mod transformer, determins how much more audio will be gained (or lost) when power is reduced from the exciter. Hmmm.. Goes without saying that however the carrier level was reduced the audio level should be concomitantly lowered to prevent over modulation. Easy to do, just reduce the mic gain control. That, and the natural asymetricalness of the operators voice. Lowering the output power, more audio, a 3:1 SR (Symmetry Ratio), the 25w of carrier could contain as much as 200w PEP. In order for the linear to 'cleanly' reproduce the audio, it's going to need more than what the plates of a pair of 3-500Z's can deliver (*note: I said Cleanly) Two hundred watts PEP on a 25 watt carrier comes out to 400% modulation. Would take some extreme speech processing to achieve this in the positive direction while limiting modulation to 100% negative at the same time. Far beyond the asymmetry of normal human speech. So, a pair of 3-500Zs running GG and giving, say, 10db gain, with 35 watts of drive would give 350 watts of carrier out and modulating at 100% with a reasonably asymmetric audio signal would give 1400 W. PEP. I have been using a 3-1000Z linear in this way for years with excellent results. Speaking of the human voice, there undoubtedly exist some levels of asymmetry depending on the speaker. I suspect, however that much of the asymmetry observed and reported is actually the product of nonlinearities in speech amplifier circuitry, particularly in the early, low-level stages. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] AM Amps
In a message dated 1/11/05 12:14:43 PM, [EMAIL PROTECTED] writes: well all I can say is it works.. works well as a matter of fact, and has been for 6 years :) I typically run between 350 and 400 watts of carrier every day. It looks great on the scope. Modulation envelope is perfect. 100% modulation. In 6 years Ive only lost one tube, and I accidently broke that one. I have to agree with Gary. You're seeing 1600 watts PEP and 400W of carrier OUT with a pair of GG 813s??? Does not compute! Just curious, are you talking about 400W INPUT power to the linear under carrier only condx maybe? If so, this would work out to about 133W carrier OUT and each 813 dissipating about 133W which would make more sense. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Windom Antenna
In a message dated 12/27/04 9:31:09 AM, [EMAIL PROTECTED] writes: So, in order for this to work, you have to decide what frequency you're going to operate on, on the HIGHEST frequency the antenna will cover. ie: 29MC /2 = 14.5, 7.25, 3.625, 18.125Mc. Goeff, Presume the last figure should have read 1.8125 Mc. that being the case, then L = 468/f(L) L = 468/18.125 L = 258.20689655172413793103448275862 Practically, we would ronnd this off to 258' 3 Now, you said that the 'tap is always feet times 25 divided by 180' T = 258.207ft * 25 / 180 T = 6455.17 / 180 T = 35.862068965517241379310344827586 Again, 35' 10 -- This is the distance to the tap-off point measured FROM THE CENTER OF THE ANTENNA. Single wire feeding it? Fed against Ground? Doesn't the single feed-line then become part of the radiating antenna? Yes, yes and again yes. Even if someone were to take, say the output of a link and feed it directly to the open wire feed-line, the open wire line would have to go all the way to the feed point of the antenna, wouldn't it? The feedline here is a single wire running up to the tap point. The flat top is NOT broken apart at the tap point, the single wire is merely attached there. The other side of the link (if this is the feed method used) would go to ground. I'm sorry if I'm seeming a little dense, but I can't get unwrapped from the 'single wire fed version' of this antenna. Open wire output from the link has *2* wires. I can see attaching them to some open wire line, and feeding this Wyndom antenna at 1.8125, and having the antenna resonant on 3.6250, 7.250, 14.5 (oops - can't operate there) and 29Mc, but I simply fail to understand how one wire is going to feed an antenna thas has two posts to connect to. See above. Certainly has me thinking, though. Now, if I could just come up with land that had 300' (for guy supports on both sides) I'll have to work CW on 3.6250, forget about 20m and enjoy a multi-wavelength antenna on 10m (when the band is open). Pardon the sarcasm ;-) These things actually do work and write-ups can be found in handbooks from the 30's up into the 50's and later. There was usually a caution to run the feedline away from the antenna at a right angle for at least 1/3 wavelength. Worked best over a well conducting ground and feedline length could be critical. Practically, some kind of a wire tuner would probably be required especially for multi-band use. A good ground wood be important too. I used one back in the 50's fed off a 6L6 with a pi network tank circuit. Worked well as I remember. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Windom Antenna
In a message dated 12/27/04 2:38:01 PM, [EMAIL PROTECTED] writes: Okay, let us try again. I thought the question was.. how can it be RESONANT at more than one place It's important here to draw a distinction between the antenna itself, in this case a single wire cut to a half wavelength at the lowest operating frequency, and the feed system connected to it. Neglecting details such as end effects for the moment, the antenna will exhibit resonance at the frequency for which it was cut and at multiples thereof. However, we propose to feed this antenna in a novel way, i.e., with a single wire line. Now, a single wire transmission line will exhibit, under some set of conditions, a characteristic impedance around 600 ohms. (I've never seen the derivation of this figure but all the books say so.) Mr. Windom, way back in the 1920s got the idea that by connecting such a feedline to just the right point on a halfwave piece of wire would make for a simple, easy to erect antenna AND FEED system. One would suspect the right point would be somewhere off the center of the antenna near where the radiation resistance also measured 600 ohms. Haven't read the 1929 article, but would suspect more than a little cut-and-try was involved here. My 1936 RAHB cautions that Correct antenna length and placement of the feeder should be checked experimentally for best results... In any case, Windom did apparently find a sweet spot and achieved something close to a flat, non-radiating feedline. And, the design was used successfully by a lot of guys for a long time. This is OK for a half wave (fundamental frequency) antenna but what about operation at 2, 3, 4, etc., times the original half wave frequency? Is it possible to find a single feedpoint that will be correct (i.e., match the 600 ohm feedline) for the fundamental AND all harmonics? Haven't read the original 1929 QST article but would be inclined to say no way. My 1936 HB (see above) agrees and goes on to say that the antenna SYSTEM can be used for harmonic operation but the feedline will always be radiating along with the antenna. Fine old classic design, though. Hope to get another one up again someday. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Windom Antenna
In a message dated 12/27/04 5:57:18 PM, [EMAIL PROTECTED] writes: Wouldn't it be real simple to use a Line Flattner/Antenna Tuner to the single wire transmission line, fed against good ground, to a Windom that is close to resonant on most of the bands, get on the air and enjoy its properties?? Sounds like good advice to me! Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Rothman Modulation
In a message dated 12/22/04 12:50:52 PM, [EMAIL PROTECTED] writes: Yup, I own one NOS. Manual is of course on BAMA. Under what name? Dennis D. W7QHO Glendale, CA
Re: [AMRadio] K1MAN comments on disrupting the 75m. AM Window (MP3)
In a message dated 12/21/04 10:02:27 AM, [EMAIL PROTECTED] writes: I've got Crystals for 3.970/3.980 3.990. Isn't there some broadcast station up in that part of the band, as well? The West Coast Military Radio Collectors Net meets on 3.983 +/- QRM on Saturday evenings, 2000 PT. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Antenna Tuner Wonderings
Don, What kind of crappy antennas are you using, i.e., doublets fed with coax, open wire lines, etc., or end-fed wires? Or, some combination of types maybe? Rather that building up a bunch of tuners you might consider putting your efforts into erecting a set of antennas that all worked directly off a 50 or 75 ohm coax feedlines. Half-wave dipoles, one for each band, for example, or one or more of the multi-band arrangements (G5RV, fan and trap dipole, etc.). Dennis D. W7QHO Glendale, CA
Re: [AMRadio] 3-500Z vs 4-400A
Patrick, Never tried it, but my understanding is one simply needs to tie the screen and control grids directly together on the 4-400 to make it a zero bias Class B triode. This is what is done with 813s. Not sure what kind of a peak grid-to-grid input voltage swing would be needed but 1 KV seems kinda high. Have used 807s with the 20K resistor setup. Worked FB. Have also had good luck with sweep tubes by grounding the control grids and driving the screens only. Give your scheme a try and let the rest of us know how it works out. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] 813 tx (EL-34 comment)
In a message dated 11/28/04 12:18:08 PM, [EMAIL PROTECTED] writes: Unfortunately, the audiophool community has got in on the action. People are paying top ridiculous dollar for EL-34's now. Last year at Dayton, someone bought an Apache transmitter at the flea market, paid the vendor's price for it on the spot, opened it and removed the EL-34 modulator tubes and left the rest of the transmitter at the vendor's booth. Must have been rare examples with just the right color brand name lettering or some other premium technical characteristic. Just checked and lots of these tubes currently being offered for reasonable prices on the e-place . The EL-34s are good tubes. Couple of these will put out a lot more audio running AB1 than a pair of 807s. Swapped a pair into a Viking 2 a while ago and eliminated many of the well known audio shortcomings found in the stock version of that rig. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] 813 tx (EL-34 comment)
In a message dated 11/28/04 1:12:38 PM, [EMAIL PROTECTED] writes: I am not sure how you quantify a lot more audio, but we probably could not hear the difference unless you could squeeze at least an extra 25-30 watts out of them, and even then it would be barely perceptible. Guess you've had no experience with a Viking 2. Stock, these run a pair of 807s AB1 in the modulator which just barely puts out enough audio to fully modulate the rig, even with a pair of hot tubes and the screen voltage and grid bias adjusted just so. More typically one gets flat-toping and distortion. One way to solve this problem is to modify the rig to add a proper AB2 driver (6AQ5 with negative feedback, etc.) along with regulating the screens and bias supplies. Dropping in a pair of EL-34s works just as well and is an easier mod. Never measured just exactly how much more headroom the 34s provide, but one can definitely hear the difference (believe me). Dennis D. W7QHO Glendale, CA
Re: [AMRadio] AM Usage with Linear AMPS
In a message dated 11/22/04 7:56:07 PM, [EMAIL PROTECTED] writes: One thinks of MANY sweep tubes rated for so-called Pdiss of 16 watts and 20 watts that are regularly run at hundreds of watts of RF! The tubes don't seem to melt. I think of the ubiquitous 6JS6C with a rating of 30 watts. Yaesu ran a pair of these at 260 watts input in their FT101 series. Many guys ran them at 260 watts p.e.p. on SSB and 260 watts CW. Assuming 65% efficiency, you have 35% of 260 watts going into the plates. That is to say 91 watts split between the two tubes. UH oh - POP! But no, they didn't. Yaesu's instructions were don't hold key down for more than 10 sec on tune up! Otherwise - POP! Voice is a low duty cycle signal. In SSB service the average dissipation level can be kept within reasonable limits unless heavy voice processing is involved. Then when you throttle that FT-101 back to 40 watts input on AM and go to your 30% efficiency (if it is) then you are actually putting only 20 watts carrier per tube which is SAFER. Is that correct? Actually, on AM the FT-101 is throttled back to something like 100 W INPUT, 25 - 30 W carrier OUTPUT. Optional fan recommended. How about some of the othre rigs that rated their 2 sweep tube finals for 560 Watts or even 800 watts!? Yes, the SWAN 750 for example. Had one in our Club back East. Be light on the key with this sucker or definitely POP! Dennis D. W7QHO Glendale, CA
Re: [AMRadio] BC669
In a message dated 11/19/04 5:56:37 PM, [EMAIL PROTECTED] writes: Anyone out there with a PS they want to part with??? Just picked one up in great shape...It has the E on the front not the H as most of them I have seen...Any comments on this ole timer is appreciated. Bob, For a good run down see Electric Radio #30, Oct. 1991. Dennis D. W7QHO Glendale, CA
[AMRadio] Seacoast Surplus?
All. Anyone know anything about a place called Seacoast Surplus? Put some stuff up on eBay a couple of years ago. No longer on the Bay, however, and their old e-mail address ([EMAIL PROTECTED]) doesn't work either. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Seacoast Surplus?
In a message dated 11/18/04 2:51:14 PM, [EMAIL PROTECTED] writes: A quick Google search turned up this: Seacoast Surplus [no website] -- military surplus, to include technical manuals email, [EMAIL PROTECTED] or call (617) 484-9866 Pete, Thanks. Did a search but must not have looked down the list far enougn. 73, Dennis
Re: [AMRadio] Mod xmfr
In a message dated 10/12/04 6:02:49 PM, [EMAIL PROTECTED] writes: One thing I don't like about doing different things with tubes is there is no real info on running 813's triode connected. What's the distortion values? See ER #57, Jan. 1994 for a set of curves and other info. on the 813 triode connected. Dennis D. W7QHO Glendale, CA
Re: [AMRadio] Re: AMRadio Digest, Vol 8, Issue 33
In a message dated 10/11/04 11:01:40 AM, [EMAIL PROTECTED] writes: I, too, am interested in AM nets. I have such low power and inefficient antenna I hesitate to mix it up with the big guns. 73, Ed Richards K6UUZ Ed, Let me suggest the following given your location in SOCAL: AMI net, Wed evenings 9:00PM PDT, 3870 kHZ 40M Arizona Net, Sat. Sun. 10:00AM, 7293 kHz (informal) West Coast Military Collectors Net, Sat., 9:00 PM, 3983 +/- QRM (Focus on military surplus equipment but all are welcome.) Also, look for AM activity on weekends, 3855 around 6:00AM, and in the evenings 3870 - 3885. Dennis D. W7QHO Glendale, CA AMI Director, SW Region
Re: [AMRadio] Converting old 1.8-4.0 MHz AM Marine Radios
In a message dated 9/10/04 8:25:43 AM, [EMAIL PROTECTED] writes: One of my customers (...and an old ham friend) is the senior tech at large marine dealer/service shop in Southern California. The other day while discussing a technical issue with a radio we got chatting about 2 MHz marine radios, and the old AM Radiotelephone rigs. He mentioned that he had a 20-foot shipping container's worth of the equipment sitting in his warehouse, the business owner would love to get rid of! He had pulled a couple of them out recently and they still worked OK! ...Would I be interested in 1, 2 or more of them? Mark, Care to pass contact information along? Myself and some of my friends out here would be glad to find homes for these rigs. Dennis D. W7QHO Glendale, CA
