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Author Topic: Fighting tons of RF & Misc Interferences after Antenna Upgrade  (Read 3195 times)
K1LA
Member

Posts: 5




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« on: September 17, 2011, 05:46:59 PM »

First off all,
thanks in advance for any help, I really appreciate it.

I've got two HTs a Yaesu VX8DR and a FT-60R(I usually keep the latter in the car). I had been using a Daimond SRH 320A & SRH77CA on the two HTs for slightly better performance in my house but finally decided to make the move and put up an antenna on my roof to better operate 2M, 200 & 400. Anyway, I bought a Diamond X3200a and mounted it high atop my house (which is up in the hills of Sherman Oaks CA), used high quality coax and ran it directly to my little shack in the house and eagerly awaited the performance increase I was hoping for........Unfortunately, to my disappointment the increase in range and clarity(which has been significant) has been overshadowed by harsh RF across the whole radio. I've tried many different frequencies, bands, even various operating power modes but the interference and noise is everywhere I go. I tried adjusted the squelch thresholds to the maximum but that did nothing. My friends at Ham Radio Outlet say I am likely picking up all the extra "junk" in the air now since I'm so high up in the hills and using a good antenna. I'm just wondering if/how I can eliminate this noise, at present it really makes using it nearly impossible since its just nonstop stabs(every second or two) of random transmissions, static, noise and other stuff(I'm getting all sorts of TV, VHF FD, and other hams as well as radio stations). Will using CTCSS and tone squelch(or whatever advice you guys give me) sacrifice my ability to TX/RX in other ways?

Thanks again, I can't wait for the help!
KJ6BUR

 
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N9BH
Member

Posts: 43




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« Reply #1 on: September 18, 2011, 12:42:51 PM »

It is possible that your HT receiver cannot deal well with all the now stronger signals and is experiencing IM, Intermod. Basically signals might be mixing in your receiver resulting in a new frequency that matches, say, the IF frequency. Try your other HT and see if you hear the same stufff on it. I found an ARRL article that may help you. It is titled "Intermod" - A Modern Urban Problem.  Here is the link. http://www.arrl.org/files/file/Technology/Intermod/Intermod_Urban_Problem.pdf
Here is another article titled What is Intermodulation Interference. http://www.midians.com/html/intermod-explained.asp

73
Bruce
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AA4PB
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Posts: 12768




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« Reply #2 on: September 18, 2011, 01:26:33 PM »

I think what you are experiencing is not uncommon with HTs. They don't do well with many strong signals (IM) due to limited front-end filtering (to keep size and cost down). They are designed primarily to work with the attached whip antenna. You may be able to add an external filter to help or get a mobile transceiver that as they generally have better front-end filtering.
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K1LA
Member

Posts: 5




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« Reply #3 on: September 18, 2011, 03:16:17 PM »

Thanks a lot gents.
I'll read those articles right away. For the interim I've been getting by with pretty good results using the Front End attenuator but it appears that the permanent solution will involve simply buying a 2M/440 mobile & 220 mobile for the house and I'll use my HTs in the car and for walkin around.
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K1CJS
Member

Posts: 5974




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« Reply #4 on: September 18, 2011, 09:23:11 PM »

Your last post is the right approach.  HTs are a little wider open and amplified to pick up the signals that they have to WITH A RUBBER DUCKIE ANTENNA.  When you put a good, high gain antenna on them, I would be surprised if you DIDN'T get any intermod and RF interference.

I think you'll find that a mobile rig will fix your problem.
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