RE: [AMRadio] BC-610 terminating impedance
The biggest difference with the link in the BC-610s, is that the link is on a pivot joint that is fixed on the center line of the loading coil. You can rotate the link from vertical and in line with the turns, OR you can place it perpendicular to the turns AND anywhere in between. You CANNOT take the link outside the coil proper. This vastly limits the variability of load impedances. I do not know when the fixed link coils ceased to be issued. However, the 1952 manual shows the issued coils to ALL be the rotating link variety. The animals or as most refer to them, Beasts, are indeed a horse of a different color. The A, B, C, D variants have different manuals - AND - may well have different characteristics. The E, F, G, H, I, and T-213 manual was published in October 1952. My I variant is indeed a Hallicrafters manufactured one. So noted by data plate and Hallicrafters logo on the tuning units. I believe my T-213 is a BW manufactured one. Both came with an SO-239 output connector. The I model also has the porcelain feedthroughs. When looking inside, I find the lines to the feedthroughs ALSO go with one to ground and the other to the center conductor of the SO-239. As to polarization of antennas, there is no question that long haul propogation DOES constantly change. My point was the use of the Mil issue 25ft vertical whip. As it has a very short length, its capture ability and transmission ability would be severely degraded in comparison with a manufactured Ham vertical. That was my basis for saying that I had no use for a vertical to be installed off the back of the BC-939. I have consistently used dipoles and inverted vees for my station. I have had no issues, and have been very happy with the results qith QSOs up and down the entire East Coast, and well into the MidWest. Antennas ARE the only black art left. I have always found them to interesting. As to my reference to the VSWR/SWR, I was explaining the reading into a 50 ohm dummy load that is internal to the ME-165G - NOT into a feedline. I feel very comfortable that the reading I referred to was indeed indicating that the transmitter WAS indicating a 50 ohm unbalanced output. Sorry - but I am NOT putting my antenna bridge looking back into the transmitter. I like my bridge, and am NOT looking to allow ALL of its smoke to depart. The manual for these two radios ALSO states to connect the transmitter to the BC-939 tuner by COAXIAL cable. Bob - N0DGN I may have missed something here amongst all the messages and I really am not too familiar with the BC610 but I thought it had variable loading with an adjustable 3-4 turn link. If so, it should be able to load into a fairly wide range of loads. On my variable link rig I can go down to about 10 ohms load by pulling the link out to maintain the proper plate current, but with the link in all the way the proper loading (indicated by plate current)is reached when the load is about 100 ohms. Of course if the load is 10 ohms and the link pulled out for proper plate current I need to be very careful not to pour the coals on with the plate voltage or the link will over heat. I have been able to load to proper plate current with a 300 ohm load but I had to parallel tune my link instead of series tune.
Re: [AMRadio] BC-610 terminating impedance
Barrie, Download a copy of the manual, TM 11-286. This can be gotten from: http://eshop1.chem.buffalo.edu/Beastly-610.html This is WB2FCNs web site. The area you want to look at in the TM starts around page 43. In the Military versions of the HT-4, (BC-610s), there are what looks like HV fuse clips on the top of the final loading cap. Depending which loading coil is used, either C-455 or C-454, dictates whether you use a 55uuf or a 100 uuf vacuum capacitor. If I had spares, I'd hook up with you and we'd talk. Unfortunately I do NOT. There are OTHER changes that MUST be made to the TX - OR - damage can occur. These are some MINOR rewiring that are COMPLETELY reversible! If you own and use a BC-939 tuner, it ALSO must have some rewiring done, and use of another one or two vacuum caps are used. With the BC-939, the long wire specified for operations from 1Mc to 2 Mc is 125 ft. As to the HT-5 speech amplifier, I strongly suspect that a BC-614 speech amp CAN be used in lieu of the HT-5. Watch that E place for them to turn up. They do from time to time. The other place to go would be the T-368 BC-610 mail list through QTH.NET. Join the list and meet some other owners of the BEASTS! Bob - N0DGN With all this interesting discussion about the BC-610 I'm reminded of a question I asked a while ago regarding the padder-cap for 160 operation. I do not have a BC-610, nor, other than photos, have I ever seen one. I do have the Hallicrafters HT4-B, which was made in 1938, and was the basis for the BC-610. In the HT4-B, there is a platform in the rear left corner of the RF compartment with four banana jacks. These jacks are hard-wired in such a fashion that if a capacitor were plugged into two of the jacks it would be in parallel with the variable tune cap. I was told, years ago on the air, that this assembly was to be used for a plugin fixed air capacitor for low frequency operation. I use a 50pf vacuum cap for 160 operation, but I'd certainly like to know more about the plugin air cap. And, if any still exist, because I'd certainly be in the market for one. Also, I'm still looking for the HT5 speech amp. TNX, Barrie, W7ALW --- [This E-mail scanned for viruses by Declude EVA] __ 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 terminating impedance
Bob: I've got my HT4-B working FB, for many years. I own a BC-939, but I've never attempted to use it. I have the BC-614 speech amp, and this is what I've been using. The only reason I'd like to have the HT5 is that it's what was originally used with the rig. My questions regarding the HT4-B are mostly motivated by the possibility that there are some differences between it and the BC-610. There are cosmetic differences, and the HT4 has one more meter. And, possibly, the shelf with the socket for the air-padder cap. 73, Barrie, W7ALW --- [This E-mail scanned for viruses by Declude EVA]
Re: [AMRadio] BC-610 terminating impedance
Barrie, There ARE different tube line-ups between the HT-5 and the BC-614. From your description of the mounting for the shelf and socket for the padder cap, there are obviously differences inside the BC-610 vs. the HT-4. I'm curious as to what differences in meters there is. I have one for filament voltage, one for tweaking the oscillator - it is multi-functional with a function switch, and then there is the plate current meter. The BC-614 has of course its own meter for modulation current. The BC-939 has an RF Ammeter. Bob - N0DGN Barrie Smith wrote: Bob: I've got my HT4-B working FB, for many years. I own a BC-939, but I've never attempted to use it. I have the BC-614 speech amp, and this is what I've been using. The only reason I'd like to have the HT5 is that it's what was originally used with the rig. My questions regarding the HT4-B are mostly motivated by the possibility that there are some differences between it and the BC-610. There are cosmetic differences, and the HT4 has one more meter. And, possibly, the shelf with the socket for the air-padder cap. 73, Barrie, W7ALW -- Bob - NØDGN +--+ | \\//\\// | | (@ @) Bob Bethman - NØDGN(@ @) | +---oOOo-(_)-oOOo--oOOo-(_)-oOOo---+ | NØDGN AMRadio Manassas, VA|REAL Tube Radio and AM| +---+--+ | Manassas Radio - Home of Homemade Kielbasa Pirogi| +---+--+ | Bob Bethman\\\|/// The absence of a danger | | rbethman(at)comcast.net \\ ~ ~ // signal does *NOT* mean | | (/ @ @ /) that everything is OK | +-oOOo-(_)-oOOo+ | http://home.comcast.net/~rbethman| | 1 BC-61ØI w/BC-614I,1 T-213/GRC-26 w/BC614I,1 '51 Collins R-390A | | SP-600/NR Type 159, Heath DX-60, Apache, Mohawk, SX-101, HT-32A | +---.oooO---Oooo.---.oooO---Oooo.--+ | () () () () | |\ ( ) / \ ( ) / | | \ _) ( _/ \ _) ( _/| +--+ | Amateur Astronomer - Celestron Nexstar 8 | | 12 f5 Dob coming soon! Being built | | Meade ETX-6Ø| | 38 Deg 46'48.62' N - 77 Deg 28'26.89 W | +--+ | Opinions expressed are that of my own and do not necessarily | | coincide with or represent those of ANYONE else | +--.oooO---Oooo.---+ | () () | | \ ( ) /| |\ _) ( _/ | |ALL E-mail received and sent scanned by AVG Norton System Works | +--+
Re: [AMRadio] BC-610 terminating impedance
Barrie, There ARE different tube line-ups between the HT-5 and the BC-614. I did not know that! Will have to do some research. From your description of the mounting for the shelf and socket for the padder cap, there are obviously differences inside the BC-610 vs. the HT-4. I went to the previously suggested website. There was a photo of the RF compartment of a BC-610 with no capacitor shelf in sight. I'm curious as to what differences in meters there is. I have one for filament voltage, one for tweaking the oscillator - it is multi-functional with a function switch, and then there is the plate current meter. The BC-614 has of course its own meter for modulation current. The BC-939 has an RF Ammeter. The HT4-B has five meters. From left to right they are: Plate Grid Current Excitation Plate Fil Voltage Modulation Plate (I believe that this meter performs the same function as the modulation meter in the BC-614. At least they dance about in the same fashion when I babble into the microphone) What other differences there may be, I do not know. It would be of interest (to me, at least) to find out. BTW, there is a fairly decent photo of my HT4-B on the November, 1992 (I think) cover of Electric Radio magazine. My call sign, at that time was KF7VA. Thanks to the vanity program, I'm back to my original call from the early 1950s. 73, Barrie, W7ALW Bob - N0DGN Barrie Smith wrote: Bob: I've got my HT4-B working FB, for many years. I own a BC-939, but I've never attempted to use it. I have the BC-614 speech amp, and this is what I've been using. The only reason I'd like to have the HT5 is that it's what was originally used with the rig. My questions regarding the HT4-B are mostly motivated by the possibility that there are some differences between it and the BC-610. There are cosmetic differences, and the HT4 has one more meter. And, possibly, the shelf with the socket for the air-padder cap. 73, Barrie, W7ALW -- Bob - NØDGN +--+ | \\//\\// | | (@ @) Bob Bethman - NØDGN(@ @) | +---oOOo-(_)-oOOo--oOOo-(_)-oOOo---+ | NØDGN AMRadio Manassas, VA|REAL Tube Radio and AM| +---+--+ | Manassas Radio - Home of Homemade Kielbasa Pirogi| +---+--+ | Bob Bethman\\\|/// The absence of a danger | | rbethman(at)comcast.net \\ ~ ~ // signal does *NOT* mean | | (/ @ @ /) that everything is OK | +-oOOo-(_)-oOOo+ | http://home.comcast.net/~rbethman| | 1 BC-61ØI w/BC-614I,1 T-213/GRC-26 w/BC614I,1 '51 Collins R-390A | | SP-600/NR Type 159, Heath DX-60, Apache, Mohawk, SX-101, HT-32A | +---.oooO---Oooo.---.oooO---Oooo.--+ | () () () () | |\ ( ) / \ ( ) / | | \ _) ( _/ \ _) ( _/| +--+ | Amateur Astronomer - Celestron Nexstar 8 | | 12 f5 Dob coming soon! Being built | | Meade ETX-6Ø| | 38 Deg 46'48.62' N - 77 Deg 28'26.89 W | +--+ | Opinions expressed are that of my own and do not necessarily | | coincide with or represent those of ANYONE else | +--.oooO---Oooo.---+ | () () | | \ ( ) /| |\ _) ( _/ | |ALL E-mail received and sent scanned by AVG Norton System Works | +--+ __ 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 --- [This E-mail scanned for viruses by Declude EVA] --- [This E-mail scanned for viruses by Declude EVA]
Re: [AMRadio] BC-610 terminating impedance
For anyone interested, there are some pretty good and descriptive pictures of a BC-610 E model at http://w5omr.shacknet.nu:81/~w5omr/hamstuff/AM-Stuff/BC-610/ --- 73 = Best Regards, -Geoff/W5OMR
Re: [AMRadio] BC-610 terminating impedance
Bob Wrote: Of course I have not pursued a whip installation. It would seem to be a useless endeavor as the 160, 80, 40, and 20 meter bands are normally of horizontal polarization. I see no logic in operating in cross polarization, and making communications more difficult than necessary. Hi Bob, I enjoyed your BC-610 thread. It makes me wish I had obtained one back when I had several chances. I recall a story from Dave, W6PSS when he was moving his three 610's in a trailer, and was involved in a bad traffic accident. He was OK, but the 610's did not fare well. Now about that polarization issue you mentioned. I had long in depth conversations with the late Ozona Bob, W5PYT concerning this. What I recall is that when receiving skip at HF, the polarization is constantly changing, and the QSB you experience is in part due to that. The other part is vector addition subtraction from picking up the same signal from different paths, phase, and time delay. Bob figured that if he transmitted circular polarization this would in effect reduce QSB at the receiving end. I recall he had huge diagonally mounted turnstile dipoles mounted nearly a football field high (the top). At my QTH (Austin), he was always on the S-meter peg, and NO QSB. That was a distance of 250 miles, day and night. I myself would be hesitant to put up a 80 meter vertical because my buddies close in within Texas would have trouble hearing me if they were beyond groundwave distance, and before the first hop distance. Now how does KC9VF get out so well? Doesn't he have a vertical dipole on 80 meters? For skip reception, it seems that the transmitted polarization, isn't a big issue, but more of a angle of radiation issue. Regards, Jim Candela WD5KJKO
Re: [AMRadio] BC-610 terminating impedance
Well said Jim !! There is only one antenna that works well at any given moment and that is the one that does (work well) if you are lucky. 73, Charlie, K0NG. Quoting Jim Candela [EMAIL PROTECTED]: Bob Wrote: Of course I have not pursued a whip installation. It would seem to be a useless endeavor as the 160, 80, 40, and 20 meter bands are normally of horizontal polarization. I see no logic in operating in cross polarization, and making communications more difficult than necessary. Hi Bob, I enjoyed your BC-610 thread. It makes me wish I had obtained one back when I had several chances. I recall a story from Dave, W6PSS when he was moving his three 610's in a trailer, and was involved in a bad traffic accident. He was OK, but the 610's did not fare well. Now about that polarization issue you mentioned. I had long in depth conversations with the late Ozona Bob, W5PYT concerning this. What I recall is that when receiving skip at HF, the polarization is constantly changing, and the QSB you experience is in part due to that. The other part is vector addition subtraction from picking up the same signal from different paths, phase, and time delay. Bob figured that if he transmitted circular polarization this would in effect reduce QSB at the receiving end. I recall he had huge diagonally mounted turnstile dipoles mounted nearly a football field high (the top). At my QTH (Austin), he was always on the S-meter peg, and NO QSB. That was a distance of 250 miles, day and night. I myself would be hesitant to put up a 80 meter vertical because my buddies close in within Texas would have trouble hearing me if they were beyond groundwave distance, and before the first hop distance. Now how does KC9VF get out so well? Doesn't he have a vertical dipole on 80 meters? For skip reception, it seems that the transmitted polarization, isn't a big issue, but more of a angle of radiation issue. Regards, Jim Candela WD5KJKO __ 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 This message was sent using IMP, the Internet Messaging Program.
Re: [AMRadio] BC-610 terminating impedance
- Original Message - From: Jim Candela [EMAIL PROTECTED] To: [EMAIL PROTECTED]; Discussion of AM Radio amradio@mailman.qth.net Sent: Saturday, October 29, 2005 9:39 AM Subject: Re: [AMRadio] BC-610 terminating impedance Bob Wrote: Now about that polarization issue you mentioned. I had long in depth conversations with the late Ozona Bob, W5PYT concerning this. What I recall is that when receiving skip at HF, the polarization is constantly changing, and the QSB you experience is in part due to that. The other part is vector addition subtraction from picking up the same signal from different paths, phase, and time delay. Bob figured that if he transmitted circular polarization this would in effect reduce QSB at the receiving end. I recall he had huge diagonally mounted turnstile dipoles mounted nearly a football field high (the top). At my QTH (Austin), he was always on the S-meter peg, and NO QSB. That was a distance of 250 miles, day and night. I myself would be hesitant to put up a 80 meter vertical because my buddies close in within Texas would have trouble hearing me if they were beyond groundwave distance, and before the first hop distance. Now how does KC9VF get out so well? Doesn't he have a vertical dipole on 80 meters? For skip reception, it seems that the transmitted polarization, isn't a big issue, but more of a angle of radiation issue. Regards, Jim Candela WD5KJKO Jim did you ever visit Bob, W5PYT at his shack? I was there once a few years before he died. I missed him but went out to where the transmitter was located in an old abandoned microwave transmitter site. I would guess the tower to be about 300 ft. high and so many wires hanging from it a bird could not fly within 1/4 mile of it. I didn't see a turnstile, but I would have challenged anyone to spot any of antenna in that grouping. As for Marv., his antenna is a 193 ft.tower installed like a broadcast antenna. He operated it for a while without radials until he could find time to install them. The only difference in his signal then and now with the radials, is he is a bit louder at my QTH but not a lot. I always hear his signal and if I loose him, I loose signals from stations equidistant that use dipoles. I have a friend that says the antennas are the only black art left. You calculate what it will do then install it. Then you set about making it work. I tend to agree with that logic. One thing I am convinced about is put up a dipole rather than a Vee. The mismatch is minimal but you get the voltage points up in the air. In that case the ends do not tend to induct into the ground or surrounding structures, natural or manmade. I know many people will disagree and use some magic antenna modeling calculator to prove me wrong, but I get consistently better signals reports using a dipole at 40 ft. than with a Vee at 55 ft. In Marv's case he has more tower (wire) in the air therefore more capture/radiation area. And he also has a good ground system. At the lower frequencies of BCB you see a lot of stations that you hear day and night and the low angle radiation tends to extend the coverage at night, but there are still lobes that will cover closer in. I had a vertical in Wyoming and was able to work the same stations at nigh that I did in the daytime. I only had 4 quarter wave radials under it. My signal was not as strong at night, but I still had local coverage with a good enough signal. I know I am opening a can of worms since so much of this theory depends on your installation so let the guessing begin. 73 Jim W5JO
Re: [AMRadio] BC-610 terminating impedance
This has been an interesting thread, and I learned some things about the HT4-B/BC-610. Relative to the polarization issue: I read a rather long article quite a few years ago about a ham who was also an electronics professor at a university in Italy, I believe. He set up two separate antennas, one vertical and one horizontal, feeding two separate receivers, and fed the IF output of one of the RX to the vertical plates of an O'scope, and the other RX to the horizontal plates. With each receiver tuned to the same frequency, he could watch the relative signal strength of the vertical or horizontal polorization on the 'scope. While I don't remember all the details, I do remember that when skip was involved the polorization of the incoming signal varied considerably, and the most likely polorization was a combination of both, which was a 45 degree angle trace on the scope. I think that cross-polorization only really matters on line-of-sight signals. 73, Barrie, W7ALW --- [This E-mail scanned for viruses by Declude EVA]
RE: [AMRadio] BC-610 terminating impedance
I may have missed something here amongst all the messages and I really am not too familiar with the BC610 but I thought it had variable loading with an adjustable 3-4 turn link. If so, it should be able to load into a fairly wide range of loads. On my variable link rig I can go down to about 10 ohms load by pulling the link out to maintain the proper plate current, but with the link in all the way the proper loading (indicated by plate current)is reached when the load is about 100 ohms. Of course if the load is 10 ohms and the link pulled out for proper plate current I need to be very careful not to pour the coals on with the plate voltage or the link will over heat. I have been able to load to proper plate current with a 300 ohm load but I had to parallel tune my link instead of series tune. As for SWR bridges, I think many people get the properties of loads and sources mixed up. All the SWR meters I have measure the match between the line and the load and they don't give a hoot about the source as long as there is no reactance in the line from the source. SWR is defined as the ratio of transmission line to load. Not source to line. Given the scenario of a XMITER (say 100 watts) that has been adjusted to match a 50 ohm dummy load on a 1/2 wave length of coax cable and the SWR meter is at the load end of the cable. If the load resistance is increase to 100 ohms the SWR meter should show 2:1 and the transmitter should have 1/2 output RF current, Hence 1/2 power. If the transmitters load is adjusted to compensate and bring the RF current and plate current back up to normal it will be putting out 100 watts again. But the SWR meter should still show 2:1. The 100 ohm load will get all must a hot as the 50 ohm load and in many cases you will not be able to tell the difference in temperature. If there is a slight difference it will be caused by the slight increase in loss of the transmission line due to the SWR of 2:1. This is generally not of any consequence on 80 or 40 meters. For the most part the load is still getting the 100 watts even though it is 100 ohms instead of 50 ohms. By the same token many SWR meters that are not at the load end of the cable may not give the correct reading and especially if the source is not a resistive output as most transmitters are not unless they or pre adjusted with the desired load attached with a very short cable. The reason I said a 1/2 wave length of coax in the above scenario, is because that with a 1/2 wave length (must take in effect of slow velocity of coax) the value of load resistance is reflected at the source. At a 1/4 wave length is either multiplied of divided by the SWR depending on whether the load is greater that the line characteristic impedance or less than it. Of course if the SWR is 1:1 then it doesn't matter how long the line is or where you measure it. The only need I have found for an SWR meter is, as an indicator of the tuning of an antenna tuner for random length wire or balanced line doublets. Also many solid state radios have no tuning built in and can only work right into a 50 ohm non reactive load. In this case a PI type tuner for coax fed antennas is very useful for fine tuning to the proper load. (Basically, it takes the place of an internal tune and load procedure, as older tube type radios had.) The SWR meter is a good indicator to use when it is placed at the input of the tuner and the transmitter has been pre-tuned into a 50 ohm dummy load. When the antenna tuner is adjusted correctly, as indicated by the SWR meter, the transmitter will be loaded just as it was with the dummy load and will not have to be retuned. SEE http://www.qsl.net/wa5bxo/swr/swr.htm John, WA5BXO
