RE: [AMRadio] BC-610 down=up and burnt't finals
I just remembered a funny situation where Otis, K5SWK, had some one else at his rig controls. The rig was and is single 833 modulated by a pair and this story was of many years ago. The person at the controls is now a silent key but I still won't mention his name. The story goes that Otis was down the street buying cigarettes, beer or something, and this person was visiting from out of town. Not realizing the rig had had a arc over on the tuning capacitor, that is never experiencing anything of that size before, the operator continued to talk while the big pole pegs melted the plate of the 833 in the final. The 833 had a hole burnt through the plate the size of a half dollar after the circuit breaker on the house when pop. The funny part of this story is that that tube was a very good tube and continued to work perfectly with out even a drop in grid current at full output. I ask Otis if the tube showed any color and he said that he could not see the other side but that on the side facing him there was no place for the tube to show color. He did change the tube later because he said that it was just too weird to look at the grid and heater through the hole and not see the normal little red glow that was supposed to be there on the plate. Some of those 833A's are indestructible. I have one with a shiny spot the size of a silver dollar burnt into the plate, and the glass got so hot that it softened and the vacuum began to suck in the envelope. There is a huge dimple on one side of the glass envelope. Someone gave it to me with some other junk, and before throwing it out I decided to test in in the Gates broadcast transmitter. Turns out to be one of the best 833A's in my collection. Works as well as a brand new tube. Don K4KYV
Re: [AMRadio] BC-610 down=up
So I was half correct. But it is indeed an unbalanced system. I was recalling about an article done back in '94 in an issue of Electric Radio which stated that the final only utilized half the coil. The final is single-ended, but the plate tank circuit is balanced just as in a pushpull amplifier. This is the classic plate-neutralised triode final. The other half of the coil functions to generate the out-of-phase rf voltage required to neutralise the circuit. True, the tube works into only half the coil, but the circulating current of the resonant tank circuit is present in the entire coil, which along with the split-stator variable tank capacitor make up the tuned circuit. The Q of the tank is determined by the LC ratio of the entire coil and capaciter. The circuit is inherently balanced. The flywheel effect of the tank circuit takes care of the fact that the rf pulses are introduced on only one end of the coil. The link output on the BC-610 came from the factory balanced, with two ceramic insulators at the output. I have seen many of these converted to an unbalance output by grounding one side to the cabinet and using a SO-239. But the link in the middle of the tank coil is inherently a balanced output. Don K4KYV
Re: [AMRadio] BC-610 down=up
So I was half correct. But it is indeed an unbalanced system. I was recalling about an article done back in '94 in an issue of Electric Radio which stated that the final only utilized half the coil. Of course that was a while ago. Mike(y) W3SLK - Original Message - From: "James M. Walker" <[EMAIL PROTECTED]> To: "Discussion of AM Radio" Sent: Thursday, October 27, 2005 11:55 AM Subject: Re: [AMRadio] BC-610 down=up Check the schematic for the BC-610 Jim WB2FCN - Original Message - From: "Mike Sawyer" <[EMAIL PROTECTED]> To: "Discussion of AM Radio" Sent: Wednesday, October 26, 2005 9:34 PM Subject: Re: [AMRadio] BC-610 down=up > The BC-610 has an un-balanced output. Generally, had it been 'push-pull', it > would have been with a balanced output. In essence, it only utilizes half > the coil on the jack bar. I just had this very same conversation not too > long ago. > Mike(y) > W3SLK > - Original Message - > From: "Barrie Smith" <[EMAIL PROTECTED]> > To: "Discussion of AM Radio" > Sent: Wednesday, October 26, 2005 8:47 PM > Subject: Re: [AMRadio] BC-610 down=up > > > Just curious, here. > > Someone mentioned that the BC-610 has a 50 ohm output. Well, I don't > remember ever having seen a BC-610, but I do have an HT4-B (the civilian > version of the BC-610, made in 1938), which does not (in stock form, at > least) have a 50 ohm output, it has a balanced output. > > So, I may be talking about, and giving advice about, something else. > > 73, Barrie, W7ALW > > > __ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > AMfone Website: http://www.amfone.net > AM List Admin: Brian Sherrod/w5ami > > __ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > AMfone Website: http://www.amfone.net > AM List Admin: Brian Sherrod/w5ami > > > __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami
Re: [AMRadio] BC-610 down=up
James M. Walker wrote: Check the schematic for the BC-610 Jim WB2FCN If anyone needs/wants to look at one, I have the E version at http://w5omr.shacknet.nu:81/~w5omr/hamstuff/AM-Stuff/BC-610/bc610.gif It's not the best, but it's not -that- bad. -- 73 = Best Regards, -Geoff/W5OMR
Re: [AMRadio] BC-610 down=up
Check the schematic for the BC-610 Jim WB2FCN - Original Message - From: "Mike Sawyer" <[EMAIL PROTECTED]> To: "Discussion of AM Radio" Sent: Wednesday, October 26, 2005 9:34 PM Subject: Re: [AMRadio] BC-610 down=up > The BC-610 has an un-balanced output. Generally, had it been 'push-pull', it > would have been with a balanced output. In essence, it only utilizes half > the coil on the jack bar. I just had this very same conversation not too > long ago. > Mike(y) > W3SLK > - Original Message - > From: "Barrie Smith" <[EMAIL PROTECTED]> > To: "Discussion of AM Radio" > Sent: Wednesday, October 26, 2005 8:47 PM > Subject: Re: [AMRadio] BC-610 down=up > > > Just curious, here. > > Someone mentioned that the BC-610 has a 50 ohm output. Well, I don't > remember ever having seen a BC-610, but I do have an HT4-B (the civilian > version of the BC-610, made in 1938), which does not (in stock form, at > least) have a 50 ohm output, it has a balanced output. > > So, I may be talking about, and giving advice about, something else. > > 73, Barrie, W7ALW > > > __ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > AMfone Website: http://www.amfone.net > AM List Admin: Brian Sherrod/w5ami > > __ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > AMfone Website: http://www.amfone.net > AM List Admin: Brian Sherrod/w5ami > > >
Re: [AMRadio] BC-610 down=up
Well Mike and group, The coupler itself doesn't generate TVI! The transmitter that is connected to it might, the coupler just pass along the signals that go to it. The "coupler" was never intended to , tune a dipole antenna, nor an open wire fed antenna. It was for a base fed "Whip" antenna and the manual for the SCR-399/499 called out the length of the feed cable to the base of the whip, and also the length of the whip. If you followed the manual and provided those lengths, AND also if stationary, provided the ground system suggested, the coupler worked as intended. As in it put most if not all of the RF into the wire. I think most of the stories about generating TVI are bogus, or at least leaving out all the information about the type of antenna that was being used. To ease the pain of not knowing about the usage, anyone wanting to use the BC-939(*), or the TN-339(*) coupler should first read the manuals for those units. I have learned that any "hunk" of wire will radiate, if you get the RF to it. These units provide the means for that, but they require that the guide lines for usage be followed. Jim WB2FCN - Original Message - From: "Mike Sawyer" <[EMAIL PROTECTED]> To: "Discussion of AM Radio" Sent: Wednesday, October 26, 2005 4:28 PM Subject: Re: [AMRadio] BC-610 down=up > The way I understand is that the BC-939 was a helluva TVI generator. What is > neat is that they used the exact same thing for the BC-610's younger > brother, the T-368. Only difference is they put it in a battleship grey box. > Mike(y) > W3SLK > > - Original Message - > From: "Todd, KA1KAQ" <[EMAIL PROTECTED]> > To: "Discussion of AM Radio" > Sent: Wednesday, October 26, 2005 9:23 AM > Subject: Re: [AMRadio] BC-610 down=up > > > On 10/26/05, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > > > > 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. > > Apparently Hallicrafters and/or the military considered it long enough > to qualify since the 3 position switch on front of the tuner has 'long > wire' specifically listed in the center position. My guess is that > they considered any random length beyond what would qualify as a > 'whip' to be a long wire, perhaps in the spirit of the original term. > > The odd thing about my A model is that the lower vacuum cap has been > removed and replaced with an air capacitor, screwed to the base with > heavy wire soldered to each of the two clips. It resembles a moderate > sized air variable but with only 5-6 stationary plates. Looks to > either be factory installed or later upgraded. Haven't had time yet to > investigate the value or rating. > > Very well-built piece of equipment, even if it has limited utility. > > ~ Todd/'Boomer' KA1KAQ > > > > -- -- > > > __ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > AMfone Website: http://www.amfone.net > AM List Admin: Brian Sherrod/w5ami > > __ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > AMfone Website: http://www.amfone.net > AM List Admin: Brian Sherrod/w5ami > > >
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
The BC-610, and the HT4-B both have the same final configuration, according to schematics I have for both. A link-coupled output, at least in this instance, can feed either a balanced or an unbalanced line. With both ends of the output link above ground, and attached to a balanced feeder, or load, the link can be adjusted to match the output to that load (unless that load is very much out of range out of range). With one end of the link to ground (often through a variable capacitor), and the other end above ground, and conected to an unbalanced load, the link can match an unbalanced load, such as a 50 coax. This scenario is entirely independent of whether the final is push-pull or single-ended. It comes under the broad defination of "transformation". 73, Barrie, W7ALW - Original Message - From: "Mike Sawyer" <[EMAIL PROTECTED]> To: "Discussion of AM Radio" Sent: Wednesday, October 26, 2005 7:34 PM Subject: Re: [AMRadio] BC-610 down=up The BC-610 has an un-balanced output. Generally, had it been 'push-pull', it would have been with a balanced output. In essence, it only utilizes half the coil on the jack bar. I just had this very same conversation not too long ago. Mike(y) W3SLK - Original Message - From: "Barrie Smith" <[EMAIL PROTECTED]> To: "Discussion of AM Radio" Sent: Wednesday, October 26, 2005 8:47 PM Subject: Re: [AMRadio] BC-610 down=up Just curious, here. Someone mentioned that the BC-610 has a 50 ohm output. Well, I don't remember ever having seen a BC-610, but I do have an HT4-B (the civilian version of the BC-610, made in 1938), which does not (in stock form, at least) have a 50 ohm output, it has a balanced output. So, I may be talking about, and giving advice about, something else. 73, Barrie, W7ALW __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami
Re: [AMRadio] BC-610 down=up
The BC-610 has an un-balanced output. Generally, had it been 'push-pull', it would have been with a balanced output. In essence, it only utilizes half the coil on the jack bar. I just had this very same conversation not too long ago. Mike(y) W3SLK - Original Message - From: "Barrie Smith" <[EMAIL PROTECTED]> To: "Discussion of AM Radio" Sent: Wednesday, October 26, 2005 8:47 PM Subject: Re: [AMRadio] BC-610 down=up Just curious, here. Someone mentioned that the BC-610 has a 50 ohm output. Well, I don't remember ever having seen a BC-610, but I do have an HT4-B (the civilian version of the BC-610, made in 1938), which does not (in stock form, at least) have a 50 ohm output, it has a balanced output. So, I may be talking about, and giving advice about, something else. 73, Barrie, W7ALW __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami
Re: [AMRadio] BC-610 down=up
Just curious, here. Someone mentioned that the BC-610 has a 50 ohm output. Well, I don't remember ever having seen a BC-610, but I do have an HT4-B (the civilian version of the BC-610, made in 1938), which does not (in stock form, at least) have a 50 ohm output, it has a balanced output. So, I may be talking about, and giving advice about, something else. 73, Barrie, W7ALW
RE: [AMRadio] BC-610 down=up and burnt't finals
That would be class AB1 6146s in the speech amplifier. Yep I guess I do know it pretty well. The final was built in a push pull configuration complete except for the extra tube and the extra neutralizing capacitor. Otis said, "I never put the other tube in because, I didn't want to be accused of running illegal power". I operated that station more than any other visitor to Otis's place and many times when he was away on trips to San Antonio and other places with his mobile rig in the old black Cadillac. The rig ran 3000 volts on the plates of final and modulators and the final current was about 300 ma. The antenna was about 70 ft. high and pretty near flat top. The RF current meter that was in the RG8 coax line read 4 amps, until he went to the folded dipole with 300 OHM feed line. So for anybody that thinks Otis was ever illegal (OVER 1KW DC input) HE WAS NOT John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of W5OMR/Geoff Sent: Wednesday, October 26, 2005 5:43 PM To: Discussion of AM Radio Subject: Re: [AMRadio] BC-610 down=up and burnt't finals His homebrew speech-amp uses a pair of 6146's in Class B, to drive the push-pull 833's. 73 = Best Regards, -Geoff/W5OMR __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami
Re: [AMRadio] BC-610 down=up and burnt't finals
John E. Coleman (ARS WA5BXO) wrote: <>Not disputing any of what you said Bob. I just remembered a funny situation where Otis, K5SWK, had some one else at his rig controls. The rig was and is single 833 modulated by a pair and this story was of many years ago. The person at the controls is now a silent key but I still won't mention his name. The story goes that Otis was down the street buying cigarettes, beer or something, and this person was visiting from out of town. Not realizing the rig had had a arc over on the tuning capacitor, that is never experiencing anything of that size before, the operator continued to talk while the big pole pegs melted the plate of the 833 in the final. The 833 had a hole burnt through the plate the size of a half dollar after the circuit breaker on the house when pop. The funny part of this story is that that tube was a very good tube and continued to work perfectly with out even a drop in grid current at full output. I ask Otis if the tube showed any color and he said that he could not see the other side but that on the side facing him there was no place for the tube to show color. He did change the tube later because he said that it was just too weird to look at the grid and heater through the hole and not see the normal little red glow that was supposed to be there on the plate. John, WA5BXO Otis's rig, is the only rig I know, that could be operated with only 1 of the pair of 833's in the modulator lit up, and no one could tell the difference. His homebrew exciter was supposed to use a 4-65, but the only 4-65 he had got damaged, or something, so he hastily lashed up an adapter plate for a pair of 6146's. Those are probably the same tubes that are in the exciter. His homebrew speech-amp uses a pair of 6146's in Class B, to drive the push-pull 833's. Everything in that station was homebrew. Oh, I don't mean he wound his own resistors, or blew glass to make tubes out of, but you know what I mean.. gather up a bunch of parts, assemble 'em in such a way as to cooerce a butt-load of electrons out of the wall, into thin air, and have 'em reappear at the other end intact, again. Ah, the magic of Radio and homebrewing! I know you know all about the station there, John... but not everyone knows Otis' rig (or Otis, for that matter!) like you do. Sure miss hearing that signal on the air. Sure will be good to get him back on, soon. -- 73 = Best Regards, -Geoff/W5OMR
RE: [AMRadio] BC-610 down=up and burnt't finals
Not disputing any of what you said Bob. I just remembered a funny situation where Otis, K5SWK, had some one else at his rig controls. The rig was and is single 833 modulated by a pair and this story was of many years ago. The person at the controls is now a silent key but I still won't mention his name. The story goes that Otis was down the street buying cigarettes, beer or something, and this person was visiting from out of town. Not realizing the rig had had a arc over on the tuning capacitor, that is never experiencing anything of that size before, the operator continued to talk while the big pole pegs melted the plate of the 833 in the final. The 833 had a hole burnt through the plate the size of a half dollar after the circuit breaker on the house when pop. The funny part of this story is that that tube was a very good tube and continued to work perfectly with out even a drop in grid current at full output. I ask Otis if the tube showed any color and he said that he could not see the other side but that on the side facing him there was no place for the tube to show color. He did change the tube later because he said that it was just too weird to look at the grid and heater through the hole and not see the normal little red glow that was supposed to be there on the plate. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Wednesday, October 26, 2005 3:58 PM To: Discussion of AM Radio; Discussion of AM Radio Subject: Re: [AMRadio] BC-610 down=up 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. Seems interesting to me that this old radio was used in WWII, Korea, AND Viet Nam with all of this working JUST FINE. If you don't like the BC-939 and its settings, you just erect dipoles for each band desired. Just DON'T use a trap dipole. You WIL NOT get a proper tune and load! Of course if you want to stock up on a BUNCH of 250THs, you CAN have it you way. I've got one that someone sent me when they insisted on THEIR way. There is very definitive light all the way through opposing sides in the middle of the plate. YMMV Bob - N0DGN My 250THs are just fine! > On 10/26/05, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > > > > 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. > > Apparently Hallicrafters and/or the military considered it long enough > to qualify since the 3 position switch on front of the tuner has 'long > wire' specifically listed in the center position. My guess is that > they considered any random length beyond what would qualify as a > 'whip' to be a long wire, perhaps in the spirit of the original term. > > The odd thing about my A model is that the lower vacuum cap has been > removed and replaced with an air capacitor, screwed to the base with > heavy wire soldered to each of the two clips. It resembles a moderate > sized air variable but with only 5-6 stationary plates. Looks to > either be factory installed or later upgraded. Haven't had time yet to > investigate the value or rating. > > Very well-built piece of equipment, even if it has limited utility. > > ~ Todd/'Boomer' KA1KAQ > __ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami
Re: [AMRadio] BC-610 down=up
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. Seems interesting to me that this old radio was used in WWII, Korea, AND Viet Nam with all of this working JUST FINE. If you don't like the BC-939 and its settings, you just erect dipoles for each band desired. Just DON'T use a trap dipole. You WIL NOT get a proper tune and load! Of course if you want to stock up on a BUNCH of 250THs, you CAN have it you way. I've got one that someone sent me when they insisted on THEIR way. There is very definitive light all the way through opposing sides in the middle of the plate. YMMV Bob - N0DGN My 250THs are just fine! > On 10/26/05, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > > > > 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. > > Apparently Hallicrafters and/or the military considered it long enough > to qualify since the 3 position switch on front of the tuner has 'long > wire' specifically listed in the center position. My guess is that > they considered any random length beyond what would qualify as a > 'whip' to be a long wire, perhaps in the spirit of the original term. > > The odd thing about my A model is that the lower vacuum cap has been > removed and replaced with an air capacitor, screwed to the base with > heavy wire soldered to each of the two clips. It resembles a moderate > sized air variable but with only 5-6 stationary plates. Looks to > either be factory installed or later upgraded. Haven't had time yet to > investigate the value or rating. > > Very well-built piece of equipment, even if it has limited utility. > > ~ Todd/'Boomer' KA1KAQ > __ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami
Re: [AMRadio] BC-610 down=up
The way I understand is that the BC-939 was a helluva TVI generator. What is neat is that they used the exact same thing for the BC-610's younger brother, the T-368. Only difference is they put it in a battleship grey box. Mike(y) W3SLK - Original Message - From: "Todd, KA1KAQ" <[EMAIL PROTECTED]> To: "Discussion of AM Radio" Sent: Wednesday, October 26, 2005 9:23 AM Subject: Re: [AMRadio] BC-610 down=up On 10/26/05, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > > 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. Apparently Hallicrafters and/or the military considered it long enough to qualify since the 3 position switch on front of the tuner has 'long wire' specifically listed in the center position. My guess is that they considered any random length beyond what would qualify as a 'whip' to be a long wire, perhaps in the spirit of the original term. The odd thing about my A model is that the lower vacuum cap has been removed and replaced with an air capacitor, screwed to the base with heavy wire soldered to each of the two clips. It resembles a moderate sized air variable but with only 5-6 stationary plates. Looks to either be factory installed or later upgraded. Haven't had time yet to investigate the value or rating. Very well-built piece of equipment, even if it has limited utility. ~ Todd/'Boomer' KA1KAQ __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami
Re: [AMRadio] BC-610 down=up
On 10/26/05, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > > 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. Apparently Hallicrafters and/or the military considered it long enough to qualify since the 3 position switch on front of the tuner has 'long wire' specifically listed in the center position. My guess is that they considered any random length beyond what would qualify as a 'whip' to be a long wire, perhaps in the spirit of the original term. The odd thing about my A model is that the lower vacuum cap has been removed and replaced with an air capacitor, screwed to the base with heavy wire soldered to each of the two clips. It resembles a moderate sized air variable but with only 5-6 stationary plates. Looks to either be factory installed or later upgraded. Haven't had time yet to investigate the value or rating. Very well-built piece of equipment, even if it has limited utility. ~ Todd/'Boomer' KA1KAQ
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] BC-610 down=up
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. At my Rochester, NY QTH I used four or the 44 ft. end fed long wires oriented to the cardinal points. the system worked quite well into Europe, and Asia, and South America, using my BC-610 on CW and RTTY. I also used a full size 160 meter Loop fed with open wire line to a homebrew antenna tuner which coupled the 50 ohm output of the BC-610 to the open wire feed-line. The BC-939 work quite well as long as it is used as it was designed to be used. As for the whip antenna, that measures 15 feet and is used in mobile work from the shelter that housed the AN/GRC-26 that used the BC-610 and a pair BC-348 receivers. Been there, done that! Lots of folks try to couple to a dipole antenna, the correct use is to use the whip also when the vehicle is parked, and put in an 8 foot ground out to aid in the matching to the whip or long-wire. If you cut a dipole to "a correct length" for the operating frequency then you can feed it with 50 ohm coax and plug that into the BC-610 output connector which is 50 ohms. FWIW Your mileage may vary. Jim WB2FCN Barrie Smith wrote: > > Todd: > > You mentioned that you have the '939 antenna tuner that matches the BC-610. > I have one, as well. Be aware that this tuner is designed to match a > (relatively) short whip, only. > > Won't do a thing for you on any "normal" ham antenna. > > 73, Barrie, W7ALW > > __ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > AMfone Website: http://www.amfone.net > AM List Admin: Brian Sherrod/w5ami
Re: [AMRadio] BC-610 down=up
Todd: You mentioned that you have the '939 antenna tuner that matches the BC-610. I have one, as well. Be aware that this tuner is designed to match a (relatively) short whip, only. Won't do a thing for you on any "normal" ham antenna. 73, Barrie, W7ALW
Re: [AMRadio] BC-610 down=up
On 10/25/05, VJB <[EMAIL PROTECTED]> wrote: > Todd, > > I bet you will find the filament rheostat has a dead > spot in part of its travel, where the brush rested for > years until someone swapped the wires so that the > OTHER part of the excursion now gets used. > > People do this with spigots too, where off = on. To be honest, I haven't had time to do much more than a cursory checkover before powering up, so anything is possible. It's not my intention to try to actually load, tune, or in any way use the transmitter until I have a manual in front of me and have cleaned up more of the mess. I really just wanted to make sure it functioned at a basic level before I started removing the rat's nest of wires added for audio. Fil. control seems smooth over the small distance I covered, but I didn't play with it much for fear of cooking toobs! > OK, now that you've sampled the BC-610, when are you > getting after the Collins 300-G ? It's not that it > needs much... Not much, but more than you'd think. Mainly, I need to get the large ceramic tank coil back from Ray if he has it re-wound and get it reinstalled, then I can put the rest up top back together and get the iron back in. The lower deck needs paint, but that's an hour or two tops, and repainting the iron won't be an issue. The trick is going to be repairing and replacing (source?) that black HV wire going to the large oil filled caps on top, all chopped up from that Gates power reduction unit I have since removed. I'd like to have it going Thanksgiving weekend, so that it gets a shakedown run or two before the HMR. Of course, I still need to figure out how to make the 160m 'homebrew dipole' <*slapping knee*> fit my property. No crystals either, but Barry gave me the VFO cord he used with it, which plugs into one of the 40F oscillators. Should work fine lashed to one of those T-368 PTO/VFO units like you use? Maybe 1-2 good weekends of work, once everything else like winterizing the house is done, and another 300G should be joining the ranks on 160. Wx here in the northeast has been anything but helpful. ~ Todd, KA1KAQ
