| Home |
| Search |
| Today's Posts |
|
#1
August 26th 03, 09:39 PM
|
|||
|
|||
MFJ-9020 -- reducing WWV interference?
MFJ-9020 users...
Has anyone come up with an effective way to reduce or eliminate the interference from WWV? I hate having that constant high-pitched heterodyne in the 'fones. How about a 10 MHz trap at the antenna connector, or at the input to the receiver section? I thought about moving the i-f off 10 MHz a little by using a matched set of crystals, but that could get a bit expensive. I'm open to any reasonable suggestions. Please don't waste my time and your time telling me to junk the 9020 and buy an FT-817 (which I already own and like very much) or one of the myriad of other QRP rigs on the market. I want to make the 9020 work, just because. Besides, I like tinkering with QRP rigs!  73/72, Dean K5DH |
|
#2
August 26th 03, 11:44 PM
|
|||
|
|||
|
Bob Miller ) writes:
On Tue, 26 Aug 2003 20:39:45 GMT, (K5DH) wrote: MFJ-9020 users... Has anyone come up with an effective way to reduce or eliminate the interference from WWV? I hate having that constant high-pitched heterodyne in the 'fones. How about a 10 MHz trap at the antenna connector, or at the input to the receiver section? I thought about moving the i-f off 10 MHz a little by using a matched set of crystals, but that could get a bit expensive. Hmm, my little qrp ten-tec 1320 has an IF of 6.144 mhz. The rig has six HC-49 style crystals at that frequency, and they don't look that expensive. (Whole rig only cost $95.) Bob k5qwg I'm open to any reasonable suggestions. Please don't waste my time and your time telling me to junk the 9020 and buy an FT-817 (which I already own and like very much) or one of the myriad of other QRP rigs on the market. I want to make the 9020 work, just because. Besides, I like tinkering with QRP rigs! 73/72, Dean K5DH Both frequencies mentioned, 10MHz and I thought 6.144MHz (though I can't remember what it's used for) are common frequencies for crystals, so they are a commodity item, and inexpensive. You can get them cheap, and if you need to go through a bunch to get a match, it won't cost too much. Moving to some specific frequency likely will mean expensive crystals because they will need to be custom made. If you move the existing IF frequency far enough, you'll then have to start messing with the rest of the circuitry. An obvious choice would be in the 9MHz range, because there were plenty of CB crystals in that range. 10.240MHz is common, and cheap, and maybe that is close enough to not cause other problems. I don't know what the rig is, I don't suppose it's a mere receiver? If so, then an obvious choice would be to get one or a few 10MHz crystals, which are cheap, and make a simple filter that goes between the antenna and the receiver. Even if it's a transceiver, the scheme would work so long as a point after the TR switching was located. Mind you, a front end filter won't solve the problem if the signal is getting into the IF directly. If the unit isn't shielded well, this might be the problem. And if it is the problem, a filter between the antenna and the receiver won't do anything because the signal is completely bypassing it. Michael VE2BVW |
|
#3
August 26th 03, 11:44 PM
|
|||
|
|||
|
Bob Miller ) writes:
On Tue, 26 Aug 2003 20:39:45 GMT, (K5DH) wrote: MFJ-9020 users... Has anyone come up with an effective way to reduce or eliminate the interference from WWV? I hate having that constant high-pitched heterodyne in the 'fones. How about a 10 MHz trap at the antenna connector, or at the input to the receiver section? I thought about moving the i-f off 10 MHz a little by using a matched set of crystals, but that could get a bit expensive. Hmm, my little qrp ten-tec 1320 has an IF of 6.144 mhz. The rig has six HC-49 style crystals at that frequency, and they don't look that expensive. (Whole rig only cost $95.) Bob k5qwg I'm open to any reasonable suggestions. Please don't waste my time and your time telling me to junk the 9020 and buy an FT-817 (which I already own and like very much) or one of the myriad of other QRP rigs on the market. I want to make the 9020 work, just because. Besides, I like tinkering with QRP rigs! 73/72, Dean K5DH Both frequencies mentioned, 10MHz and I thought 6.144MHz (though I can't remember what it's used for) are common frequencies for crystals, so they are a commodity item, and inexpensive. You can get them cheap, and if you need to go through a bunch to get a match, it won't cost too much. Moving to some specific frequency likely will mean expensive crystals because they will need to be custom made. If you move the existing IF frequency far enough, you'll then have to start messing with the rest of the circuitry. An obvious choice would be in the 9MHz range, because there were plenty of CB crystals in that range. 10.240MHz is common, and cheap, and maybe that is close enough to not cause other problems. I don't know what the rig is, I don't suppose it's a mere receiver? If so, then an obvious choice would be to get one or a few 10MHz crystals, which are cheap, and make a simple filter that goes between the antenna and the receiver. Even if it's a transceiver, the scheme would work so long as a point after the TR switching was located. Mind you, a front end filter won't solve the problem if the signal is getting into the IF directly. If the unit isn't shielded well, this might be the problem. And if it is the problem, a filter between the antenna and the receiver won't do anything because the signal is completely bypassing it. Michael VE2BVW |
|
#4
August 27th 03, 10:59 AM
|
|||
|
|||
|
|
|
#5
August 27th 03, 10:59 AM
|
|||
|
|||
|
|
| Reply |
| Thread Tools | Search this Thread |
| Display Modes | |
|
|
Linear Mode
