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#1
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Where are you? I'm in Illinois and just got one of the clocks. I know it
helps you not not a bit for me to say mine sync'ed up quickly, but everybody says that kinda' stuff (:-).. Don't think there is anything to buy... Make is the only way. The instructions for mine say that it only listens at certain times and can take a few _DAYS_ to sync up. That seems strange to me...oh well. Ivan's passive loop is a VERY good idea - easy. I don't think cinder block walls will matter. Search for "lowfer". I wanted to actually hear WWVB and do a little SWLing for NDBs (300-500KHz) w/ my new IC 706 and did some snooping. A good loop takes a little bit of work. -- Steve N, K,9;d, c. i My email has no u's. "Chris Campbell" wrote in message m... I'm trying to get a radio clock to sync up with WWVB (60 kHz out of Colorado). In the place that I want to place the clock, I can not get it to sync, even at night when the signal is stronger. Inside the clock is a small ferrite-core loopstick antenna. I figured out which way the gain pattern pointed on the thing (i.e. not along the axis of the ferrite rod) and tried positioning the clock for maximum signal, but no luck. So now I'd like to try a better antenna. I won't have the time to make one myself, and I'd probably do it badly anyway. It seems that I should be able to buy an antenna for this fairly cheaply (thank you to my capitalist exploiter overlords!), but I can't find one. Ideally, one designed for WWVB's 60 kHz would be great, but I'll settle for anything really, as long as it claims to have some decent gain at 60 kHz. This clock is going inside a building, inside two layers of cinder block / concrete walls, so it's possible that I just won't be able to get a signal in there no matter what I use. The external-antenna-and-a-wire-run concept is the next step, but I'd rather not to that unless I have to. We're moving out of that facility in a few months so that would be wasted labor. What are some sources for loopstick antennas? On another note, in searching this forum, someone said: An LF loopstick antenna wound on a 1/2 inch diameter rod is *much* less efficient than a 1-meter square air loop Assuming I have the space, am I better off trying this with a few big loops of wire instead of a small ferrite loopstick? What are the rules of thumb for comparing the two types of loop antennas? Thanks! |
#2
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Steve Nosko wrote:
Where are you? I'm in Illinois and just got one of the clocks. I know it helps you not not a bit for me to say mine sync'ed up quickly, but everybody says that kinda' stuff (:-).. Don't think there is anything to buy... Make is the only way. The instructions for mine say that it only listens at certain times and can take a few _DAYS_ to sync up. That seems strange to me...oh well. Ivan's passive loop is a VERY good idea - easy. I don't think cinder block walls will matter. Search for "lowfer". I wanted to actually hear WWVB and do a little SWLing for NDBs (300-500KHz) w/ my new IC 706 and did some snooping. A good loop takes a little bit of work. All you will hear is nothing, unless your detector and audio amp goes down to DC. The modulation rate is one bit per second, by reducing the carrier level by 10 dB. There is no audio modulation, because the signal is also a frequency standard. The only way you would hear it would be to mix a signal to beat against WWVB to produce a heterodyne in the radio's pass band. -- We now return you to our normally scheduled programming. Take a look at this little cutie! ;-) http://home.earthlink.net/~mike.terrell/photos.html Michael A. Terrell Central Florida |
#3
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![]() "Michael A. Terrell" wrote: Steve Nosko wrote: Where are you? I'm in Illinois and just got one of the clocks. I know it helps you not not a bit for me to say mine sync'ed up quickly, but everybody says that kinda' stuff (:-).. Don't think there is anything to buy... Make is the only way. The instructions for mine say that it only listens at certain times and can take a few _DAYS_ to sync up. That seems strange to me...oh well. Ivan's passive loop is a VERY good idea - easy. I don't think cinder block walls will matter. Search for "lowfer". I wanted to actually hear WWVB and do a little SWLing for NDBs (300-500KHz) w/ my new IC 706 and did some snooping. A good loop takes a little bit of work. All you will hear is nothing, unless your detector and audio amp goes down to DC. The modulation rate is one bit per second, by reducing the carrier level by 10 dB. There is no audio modulation, because the signal is also a frequency standard. The only way you would hear it would be to mix a signal to beat against WWVB to produce a heterodyne in the radio's pass band. -- We now return you to our normally scheduled programming. Take a look at this little cutie! ;-) http://home.earthlink.net/~mike.terrell/photos.html Michael A. Terrell Central Florida I hear it fine with several different receivers provided I use either CW or SSB. But! I CANNOT hear it on my IC-706; it does not seem to come alive until somewhere between 200 and 300kHz. Dave |
#4
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Dave Holford wrote:
I hear it fine with several different receivers provided I use either CW or SSB. But! I CANNOT hear it on my IC-706; it does not seem to come alive until somewhere between 200 and 300kHz. Dave Try using a HP312 series Frequency Selective Voltmeter for the receiver. Build a 60 KHz tuned loop and look at it with a scope. You can see the modulation, because it is so slow. It is a CW signal with a 10 dB gain reduction modulation with a maximum level change of twice per second. (Normal and -10 dB) I built a three foot square copper loop with an insulator where it was mounted on a cast aluminum electrical box, and wound 20 turns of wire inside the 3/4" copper pipe after it was soldered together. I used an op amp to give some gain,. and I could watch the modulation. The big problem was a neighbor about a half mile away left a TV set on 24/7 and the horizontal oscillator drifted after the station went off, and the harmonics would drift right through 60 KHz. I wanted to use it for a frequency standard, but I couldn't do it there. I will try it again, some day, now that I have a couple miles of woods between me and Colorado. I have enough gain to get around 12V P-P at the power inserter. I used 75 ohm cable and "F" fittings because they were handy, but I would use Mini Circuits MMICs and 50 Ohm cable if I built another outdoor 60 KHz antenna. -- We now return you to our normally scheduled programming. Take a look at this little cutie! ;-) http://home.earthlink.net/~mike.terrell/photos.html Michael A. Terrell Central Florida |
#5
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![]() "Michael A. Terrell" wrote: Dave Holford wrote: I hear it fine with several different receivers provided I use either CW or SSB. But! I CANNOT hear it on my IC-706; it does not seem to come alive until somewhere between 200 and 300kHz. Dave Try using a HP312 series Frequency Selective Voltmeter for the receiver. Build a 60 KHz tuned loop and look at it with a scope. You can see the modulation, because it is so slow. It is a CW signal with a 10 dB gain reduction modulation with a maximum level change of twice per second. (Normal and -10 dB) I built a three foot square copper loop with an insulator where it was mounted on a cast aluminum electrical box, and wound 20 turns of wire inside the 3/4" copper pipe after it was soldered together. I used an op amp to give some gain,. and I could watch the modulation. The big problem was a neighbor about a half mile away left a TV set on 24/7 and the horizontal oscillator drifted after the station went off, and the harmonics would drift right through 60 KHz. I wanted to use it for a frequency standard, but I couldn't do it there. I will try it again, some day, now that I have a couple miles of woods between me and Colorado. I have enough gain to get around 12V P-P at the power inserter. I used 75 ohm cable and "F" fittings because they were handy, but I would use Mini Circuits MMICs and 50 Ohm cable if I built another outdoor 60 KHz antenna. -- We now return you to our normally scheduled programming. Take a look at this little cutie! ;-) http://home.earthlink.net/~mike.terrell/photos.html Michael A. Terrell Central Florida I have no problem receiving it on a number of different Ham and General Coverage receivers using random wires or simple vertical whips. I also hear it well with an active antenna. I have not noticed any real QRM problems on 60kHz although there are some really strong noise sources at other frequencies nearby. Dave 45N 75W |
#6
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Dave Holford wrote:
"Michael A. Terrell" wrote: Dave Holford wrote: I hear it fine with several different receivers provided I use either CW or SSB. But! I CANNOT hear it on my IC-706; it does not seem to come alive until somewhere between 200 and 300kHz. Dave Look at the design of the front end. If it is capacitor coupled, the capacitive reactance is so high that it blocks anything below 200 KHz. In this case you can add another cap in parallel to improve the lower frequencies. Multiply the original by 100 or higher, and add it in parallel to reduce the capacitive reactance, and the attenuation. I built a broadband DC block for my bench at Microdyne that had five caps in parallel. It was flat to less that a half dB from 50 KHz to 450 MHz, and had a VSWR of less than 1.05 across the entire range. It was built to maintain a 50 ohm impedance end to end. If it has a transformer, the losses are too high at low frequencies. In that case I would build a low pass filter and pre amp, and couple it to the input of the mixer to see how it performs. You would have to shut it off to use other bands, though. Try using a HP312 series Frequency Selective Voltmeter for the receiver. Build a 60 KHz tuned loop and look at it with a scope. You can see the modulation, because it is so slow. It is a CW signal with a 10 dB gain reduction modulation with a maximum level change of twice per second. (Normal and -10 dB) I built a three foot square copper loop with an insulator where it was mounted on a cast aluminum electrical box, and wound 20 turns of wire inside the 3/4" copper pipe after it was soldered together. I used an op amp to give some gain,. and I could watch the modulation. The big problem was a neighbor about a half mile away left a TV set on 24/7 and the horizontal oscillator drifted after the station went off, and the harmonics would drift right through 60 KHz. I wanted to use it for a frequency standard, but I couldn't do it there. I will try it again, some day, now that I have a couple miles of woods between me and Colorado. I have enough gain to get around 12V P-P at the power inserter. I used 75 ohm cable and "F" fittings because they were handy, but I would use Mini Circuits MMICs and 50 Ohm cable if I built another outdoor 60 KHz antenna. -- We now return you to our normally scheduled programming. Take a look at this little cutie! ;-) http://home.earthlink.net/~mike.terrell/photos.html Michael A. Terrell Central Florida I have no problem receiving it on a number of different Ham and General Coverage receivers using random wires or simple vertical whips. I also hear it well with an active antenna. I have not noticed any real QRM problems on 60kHz although there are some really strong noise sources at other frequencies nearby. Dave 45N 75W They only signals I saw were WWVB, and that damned TV's harmonics drifting through 60 KHz after the station went off the air. The guy was only there a couple days a month, and left the TV on to make people think he was home. -- We now return you to our normally scheduled programming. Michael A. Terrell Central Florida |
#8
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Steve and group:
I tuned my IC706 down there, and apparently the front end filters block anything that low. My Kenwood R-5000 hears the signal fine with a 100' random wire. The radio I would really like to try, the RCA AR-88LF, only goes down to 74 KHz, and I sold the old RAK? RAL? Navy monster which covers that range, so I have to believe the R-5000 on this one. The signal is a little weak mid-day, but strong the remainder of the time. I bought one of the cheap "atomic" wris****ches last month, and have been experimenting with orientation for sync. It has an indicator which shows if it has locked up in the last 24 hours, and the manual says it tries at 3 AM in whatever time zone it is set to. The wall clocks also have a lock indicator, and their manual says they try several times in the wee hours if the first try doesn't result in synchronization. But BEWARE, I have now observed two different instances, once each with two different clocks, that while indicating that resynchronization had occurred the previous evening, the clock indicated the time which was exactly 1 minute off, apparently due to a thunderstorm during the night. The orientation where the wris****ch synchronizes reliably is face down, BTW. -- Crazy George Remove N O and S P A M imbedded in return address |
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