Hi Dave, Does MFJ tell you to put the meter coil inside the trap? I've built my fair share of coax antenna traps. I would think that tightly coupling the meter coil to the trap on the inside will disturb the L and C of the trap and give a false indication of resonance. When I tune traps I suspend them so they're away from any other objects (as they are when the antenna is erected) and loosely couple the GDO on the outside of the trap. Just my 2 cents. Thanks for the great videos! 73! Tom
I would think that putting the dip meter coil inside would de-tune the trap lower. You should put the meter as far away as you can, but the coils in parallel, and still get a dip indication. That would be a more accurate way to measure.
Jimmy, thanks for the comment. The MFJ coil seems to change frequency, too when moving the trap back and forth along the coil. I've been adjusting the trap on the coil until I find the most resonate spot on the meter (lowest SWR reading). I'm not sure this is correct. I'll try the wire next time. MFJ shows using a wire, in a video here, for a series circuit but they use the coil for the parallel circuit. Have 20/40m trap dipole up now and having a problem with best SWR on 20 at 1.7:1.
I used the coils from MFJ but a cheaper way is just a clip lead in a circle on a white plastic cutting board on a wood table. This made me quite mad that I bought the coils from MFJ for the meter. When a wire circle on the table from GND and antenna Hot out of the meter works as well and sometimes better. Also working towards X=0 is the best way I have found as that shows that C and L are equal which indicates resonance. Great artical thanks for doing it. 73 Jimmy, ARRL TC, WX9DX
Yes, MFJ has a video about hanging a coil or trap over the coil. Frequency indicated on the meter does change if you move the coil back and forth. The instructions that come with the coil adapters is not very detailed. The small UHF adapter that came in the set doesn't seem to work but it was too late to return it after finally needing to use it. MFJ is too busy with Facebook posts to be concerned and when complaining about quality would rather call an unhappy customer a troll. Thanks & 73! :)
Hi Dave I have an idea for a remote shut off/On coaxial trap for cable company. No more climbing the pole! If you can direct me to someone that would like to partner or introduce it to a company please reply. TY!
Hi Bob, TH-cam has changed their web pages and I no longer have an Inbox here for messages. I don't know if you've seen my page on Facebook. Please visit my website, the link is on my YT channel, then on my main webpage click the Facebook Like button or follow the link. Then you can send me a message through Zed Zed's Workbench on Facebook. I don't know if I can help but will try. Some things are still new to me and I'm still trying to figure out this Google +1 thing. 73. :)
Hi John, The adapter is made by MFJ. It's an accessory for the MFJ SWR analyzer that you purchase separately. Thanks for watching and 73! :)
Hi Dave,
Does MFJ tell you to put the meter coil inside the trap?
I've built my fair share of coax antenna traps. I would think that
tightly coupling the meter coil to the trap on the inside will disturb
the L and C of the trap and give a false indication of resonance.
When I tune traps I suspend them so they're away from
any other objects (as they are when the antenna is
erected) and loosely couple the GDO on the outside of the trap.
Just my 2 cents.
Thanks for the great videos!
73! Tom
I would think that putting the dip meter coil inside would de-tune the trap lower. You should put the meter as far away as you can, but the coils in parallel, and still get a dip indication. That would be a more accurate way to measure.
Jimmy, thanks for the comment. The MFJ coil seems to change frequency, too when moving the trap back and forth along the coil. I've been adjusting the trap on the coil until I find the most resonate spot on the meter (lowest SWR reading). I'm not sure this is correct. I'll try the wire next time. MFJ shows using a wire, in a video here, for a series circuit but they use the coil for the parallel circuit. Have 20/40m trap dipole up now and having a problem with best SWR on 20 at 1.7:1.
I used the coils from MFJ but a cheaper way is just a clip lead in a circle on a white plastic cutting board on a wood table. This made me quite mad that I bought the coils from MFJ for the meter. When a wire circle on the table from GND and antenna Hot out of the meter works as well and sometimes better. Also working towards X=0 is the best way I have found as that shows that C and L are equal which indicates resonance.
Great artical thanks for doing it.
73
Jimmy, ARRL TC, WX9DX
Yes, MFJ has a video about hanging a coil or trap over the coil. Frequency indicated on the meter does change if you move the coil back and forth. The instructions that come with the coil adapters is not very detailed. The small UHF adapter that came in the set doesn't seem to work but it was too late to return it after finally needing to use it. MFJ is too busy with Facebook posts to be concerned and when complaining about quality would rather call an unhappy customer a troll. Thanks & 73! :)
Would removing one turn make it easier to adjust for 10m?
Wow man, I will test. txn73!
Thank you.
Hi Dave, what is the adaptor you made for measuring trap frequencies? Is there any info how to make it and what materials you use.
73's de John VE6MAQ
Hi Dave I have an idea for a remote shut off/On coaxial trap for cable company. No more climbing the pole! If you can direct me to someone that would like to partner or introduce it to a company please reply. TY!
th-cam.com/video/FkJ1dVDkdyI/w-d-xo.html
Hi Bob, TH-cam has changed their web pages and I no longer have an Inbox here for messages. I don't know if you've seen my page on Facebook. Please visit my website, the link is on my YT channel, then on my main webpage click the Facebook Like button or follow the link. Then you can send me a message through Zed Zed's Workbench on Facebook. I don't know if I can help but will try. Some things are still new to me and I'm still trying to figure out this Google +1 thing. 73. :)