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Ferrite Magnet antenna ; parts purchase / design question
All:
Working on a ferrite antenna. Ordered parts from Ocean state electronics, ( via website) ( http://www.oselectronics.com ) bought their 14-365 Pf variable capacitor and two ferrites: one FR4-33 #33 1/2" Diameter X 4" Long and then FERRITE "LOOP STIK" ANTENNA band, 540KHz - 1600KHz. Measures 5/16" Dia. x 3 1/2" Long. Includes mounting bracket and wiring diagram. Q=25, L=788µH. LA-540................... - Now, follow this : I figure I'll use the 8 inch loopstick for the ' Primary" antenna. setting it in a window.. Hook the " primary " up to the variable capacitor via about 10 feet of co-ax wire. - so I can Tune it from 10 + feet away. THEN use the "FERRITE "LOOP STIK" ANTENNA"( part LA-540.) as a " transmitter" setting it on top of my sangean 606A; - So the primary can be tuned from far away, still usable via the capacitor and 10 + feet of wire.. - Any thoughts on this ? Sheer folley? Intellectual Property Theft? Genius ?? Happy as a Clam At High Tide.. Dan |
#2
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"Diverd4777" wrote in message ... All: Working on a ferrite antenna. Ordered parts from Ocean state electronics, ( via website) ( http://www.oselectronics.com ) bought their 14-365 Pf variable capacitor and two ferrites: one FR4-33 #33 1/2" Diameter X 4" Long and then FERRITE "LOOP STIK" ANTENNA band, 540KHz - 1600KHz. Measures 5/16" Dia. x 3 1/2" Long. Includes mounting bracket and wiring diagram. Q=25, L=788µH. LA-540................... - Now, follow this : I figure I'll use the 8 inch loopstick for the ' Primary" antenna. setting it in a window.. Hook the " primary " up to the variable capacitor via about 10 feet of co-ax wire. - so I can Tune it from 10 + feet away. THEN use the "FERRITE "LOOP STIK" ANTENNA"( part LA-540.) as a " transmitter" setting it on top of my sangean 606A; - So the primary can be tuned from far away, still usable via the capacitor and 10 + feet of wire.. - Any thoughts on this ? Sheer folley? Intellectual Property Theft? Genius ?? Happy as a Clam At High Tide.. Dan One problem might come from the capacitance of the coax connected to the tuning cap. It will restrict the tuning range. The extra capacitance will have the same effect as not being able to open the cap all the way. Otherwise, it should work. The tuning range problem will be lessened if you connect the coax to a few turns of wire wrapped by the ground side of the coil and use a similar coil on the other ferrite rod. Frank Dresser |
#3
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That peice of coax will introduce lots of aditional capacitance and
inductance. Have fun getting it to work. "Diverd4777" wrote in message ... All: Working on a ferrite antenna. Ordered parts from Ocean state electronics, ( via website) ( http://www.oselectronics.com ) bought their 14-365 Pf variable capacitor and two ferrites: one FR4-33 #33 1/2" Diameter X 4" Long and then FERRITE "LOOP STIK" ANTENNA band, 540KHz - 1600KHz. Measures 5/16" Dia. x 3 1/2" Long. Includes mounting bracket and wiring diagram. Q=25, L=788µH. LA-540................... - Now, follow this : I figure I'll use the 8 inch loopstick for the ' Primary" antenna. setting it in a window.. Hook the " primary " up to the variable capacitor via about 10 feet of co-ax wire. - so I can Tune it from 10 + feet away. THEN use the "FERRITE "LOOP STIK" ANTENNA"( part LA-540.) as a " transmitter" setting it on top of my sangean 606A; - So the primary can be tuned from far away, still usable via the capacitor and 10 + feet of wire.. - Any thoughts on this ? Sheer folley? Intellectual Property Theft? Genius ?? Happy as a Clam At High Tide.. Dan |
#4
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Thanks Frank..
- Guess I'll get the main ferrite loop to work first, then try the long leads & the coils. retuning it with 1, 2,4 then 8 foot lengths to see what obtains.. I guess Very Very thin copper wire would introduce the least capacitance ?? Dan In article , "Frank Dresser" writes: "Diverd4777" wrote in message ... All: Working on a ferrite antenna. Ordered parts from Ocean state electronics, ( via website) ( http://www.oselectronics.com ) bought their 14-365 Pf variable capacitor and two ferrites: one FR4-33 #33 1/2" Diameter X 4" Long and then FERRITE "LOOP STIK" ANTENNA band, 540KHz - 1600KHz. Measures 5/16" Dia. x 3 1/2" Long. Includes mounting bracket and wiring diagram. Q=25, L=788µH. LA-540................... - Now, follow this : I figure I'll use the 8 inch loopstick for the ' Primary" antenna. setting it in a window.. Hook the " primary " up to the variable capacitor via about 10 feet of co-ax wire. - so I can Tune it from 10 + feet away. THEN use the "FERRITE "LOOP STIK" ANTENNA"( part LA-540.) as a " transmitter" setting it on top of my sangean 606A; - So the primary can be tuned from far away, still usable via the capacitor and 10 + feet of wire.. - Any thoughts on this ? Sheer folley? Intellectual Property Theft? Genius ?? Happy as a Clam At High Tide.. Dan One problem might come from the capacitance of the coax connected to the tuning cap. It will restrict the tuning range. The extra capacitance will have the same effect as not being able to open the cap all the way. Otherwise, it should work. The tuning range problem will be lessened if you connect the coax to a few turns of wire wrapped by the ground side of the coil and use a similar coil on the other ferrite rod. Frank Dresser |
#5
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"Diverd4777" wrote in message ... Thanks Frank.. - Guess I'll get the main ferrite loop to work first, then try the long leads & the coils. retuning it with 1, 2,4 then 8 foot lengths to see what obtains.. I guess Very Very thin copper wire would introduce the least capacitance ?? Dan Actually, if you don't want/need/HAVE to use coax, your route of least capacitance would be standard television twinlead. The good foam surround stuff has virtually no capacitance, and certainly would not have enough to worry about at 10'. |
#6
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"Diverd4777" wrote in message ... Thanks Frank.. - Guess I'll get the main ferrite loop to work first, then try the long leads & the coils. retuning it with 1, 2,4 then 8 foot lengths to see what obtains.. I guess Very Very thin copper wire would introduce the least capacitance ?? Dan Thin wire would introduce the least capacitance, but there won't be much difference with reasonably spaced turns. The capacitance goes down quickly with spacing, and there's really not much spacing difference between very fine and fine wire if you wind maybe 12 turns per inch or so. That's not a magic number or anything, just wind, test and adjust. Frank Dresser |
#7
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Another thing you might want to consider is the inductance of the loopstick.
For a 14-365pF tuning cap, you need right around 260uH for the loopstick. A Q of at least 200 is desirable, for sharp tuning. Pete Frank Dresser wrote in message ... "Diverd4777" wrote in message ... All: Working on a ferrite antenna. Ordered parts from Ocean state electronics, ( via website) ( http://www.oselectronics.com ) bought their 14-365 Pf variable capacitor and two ferrites: one FR4-33 #33 1/2" Diameter X 4" Long and then FERRITE "LOOP STIK" ANTENNA band, 540KHz - 1600KHz. Measures 5/16" Dia. x 3 1/2" Long. Includes mounting bracket and wiring diagram. Q=25, L=788µH. LA-540................... - Now, follow this : I figure I'll use the 8 inch loopstick for the ' Primary" antenna. setting it in a window.. Hook the " primary " up to the variable capacitor via about 10 feet of co-ax wire. - so I can Tune it from 10 + feet away. THEN use the "FERRITE "LOOP STIK" ANTENNA"( part LA-540.) as a " transmitter" setting it on top of my sangean 606A; - So the primary can be tuned from far away, still usable via the capacitor and 10 + feet of wire.. - Any thoughts on this ? Sheer folley? Intellectual Property Theft? Genius ?? Happy as a Clam At High Tide.. Dan One problem might come from the capacitance of the coax connected to the tuning cap. It will restrict the tuning range. The extra capacitance will have the same effect as not being able to open the cap all the way. Otherwise, it should work. The tuning range problem will be lessened if you connect the coax to a few turns of wire wrapped by the ground side of the coil and use a similar coil on the other ferrite rod. Frank Dresser |
#8
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"Diverd4777" wrote in message ... Thanks Brenda: I'll try the standard television Twinlead. I really don't know anything much about electronics; or reading scematics or soldering. Maybe I should learn; from what I hear it's becoming a lost art! Dan Here's some fascinating stuff, if you're fascinated by such stuff: http://www.du.edu/~jcalvert/tech/techhom.htm#elec And, more to the point: http://www.du.edu/~etuttle/electron/elecindx.htm Any website author who writes "There is a very large number of texts on electronic circuits, most of which are too big and rather bad." is OK with me. He lists several books he's found helpful. Among them is the Radio Amateur's Handbook. I also think they are excellent. Frank Dresser |
#9
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Diverd4777 wrote:
All: Working on a ferrite antenna. Ordered parts from Ocean state electronics, ( via website) ( http://www.oselectronics.com ) bought their 14-365 Pf variable capacitor and two ferrites: one FR4-33 #33 1/2" Diameter X 4" Long and then FERRITE "LOOP STIK" ANTENNA band, 540KHz - 1600KHz. Measures 5/16" Dia. x 3 1/2" Long. Includes mounting bracket and wiring diagram. Q=25, L=788µH. LA-540................... - Now, follow this : I figure I'll use the 8 inch loopstick for the ' Primary" antenna. setting it in a window.. Hook the " primary " up to the variable capacitor via about 10 feet of co-ax wire. - so I can Tune it from 10 + feet away. THEN use the "FERRITE "LOOP STIK" ANTENNA"( part LA-540.) as a " transmitter" setting it on top of my sangean 606A; - So the primary can be tuned from far away, still usable via the capacitor and 10 + feet of wire.. - Any thoughts on this ? Sheer folley? Intellectual Property Theft? Genius ?? Happy as a Clam At High Tide.. Dan Sounds like a great project! Like anything where there are unknowns, experimentation is the fun way to go, so don't hesitate to try different things. The second, smaller ferrite to couple the signal into your receiver is presumably in parallel with the 8" loopstick. It's just that a bunch of coaxial cable is in-between. Inductors in parallel have less inductance than either of the two inductors, so this will throw you off using equations built to serve the case of one loopstick and one variable capacitor. This might cause you to need more capacitance, which fortunately is easy to do by adding a series of small caps in parallel until you achieve the desired tuning range. Someone else mentioned the extra capacitance added by the coax. I'd *think* (I may well be all wet) that this extra capacitance is a good thing given the partial loss in inductance. |
#10
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"Ross Archer" wrote in message ... Sounds like a great project! Like anything where there are unknowns, experimentation is the fun way to go, so don't hesitate to try different things. The second, smaller ferrite to couple the signal into your receiver is presumably in parallel with the 8" loopstick. It's just that a bunch of coaxial cable is in-between. Inductors in parallel have less inductance than either of the two inductors, so this will throw you off using equations built to serve the case of one loopstick and one variable capacitor. This might cause you to need more capacitance, which fortunately is easy to do by adding a series of small caps in parallel until you achieve the desired tuning range. Someone else mentioned the extra capacitance added by the coax. I'd *think* (I may well be all wet) that this extra capacitance is a good thing given the partial loss in inductance. The extra capacitance will cause a problem with the tuning range by reducing the difference in the capacitance ratio of the tuning capacitor. A 10 to 360 pf tuning cap will tune about a 4 to 1 ratio with a normal fixed inductance with a typical amount of distributed capacitance. Putting another 100 pf or more of capacitance in parallel would reduce the tuning range to less than 3 to 1, which is less than range of the AM broadcast band. Anyway, that's my instinct on this one. There's a square law relationship between the tuning ratio and the capacitance ratio but I really don't want to run the numbers. I suggested using a link of a few turns to connect the coax rather than putting the coax directly across the tuning cap in order to reduce the added capacitance. That sort of hookup would probably also reduce the energy transfer, but that gets into all that Nikola Tesla stuff, and I really, really don't want to run those numbers. Frank Dresser |
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