BAOFENG UV-5R VHF/UHF HANDHELD TRANSCEIVER PROBLEM
I Z33T home page I Z33T web pages in english I
The Baofeng UV-5R is wonderful cheap little handheld transceiver with wide-band frequency range, but nothing is perfect, so UV-5R is not perfect too.
I was tried to connect better antenna instead original antenna to my UV-5R in order to increase working range. But I noticed that with better antenna the receiving signals was actually worse !? (tried Nagoya 771, Nagoya 106, Nagoya 108, Diamond X-30 and home made Dipole for 2m band)
The corespondents send me a better receiving reports but, unfortunately, in most of the cases I copy them worse or not at all...
Thinking about this unexpected problem, I come to conclusion that connecting any better antenna to UV-5R, actually you exposes the receiver front end to strong out of band signals. Especially if you live in urban area with many RF signals around, like strong FM broadcast stations and so.
Many wide-band receivers suffering from low receiving dynamic range just because they are wide band and at their front-end (when you connect a good antenna) the receiver "see" many out of band signals as well (like strong FM broadcast signals). Those strong signals can easily block (desensitization) the receiver and we couldn`t receive weak signals of interest. By the way, a good tracking filter (which can filter out strong out-of-band signals) is impossible to include in the little transceivers of that price range.
The producer equipped this little handheld UV-5R transceiver with just good enough antenna to making local contacts, and at the same time, antenna is as bad as not being blocked by strong out of band signals...
Baofeng receiver overload and desensitization is very difficult to notice. If it is occurred, you can not receive weak signals, but only strong ones. Everything else is just as normal. When the strong signals will gone, the receiver will receive weak signals again...
- - - - - - - - - - - - - - - - - - - - - - -
Reading the forums about Baofeng, I find this post with the same common problem:
Bob Lampe wrote:
When I use my UV-5RPlus locally I have no problem but when I go to another town and try to call a friend of mine there he can hear me calling but I can not hear him or his friend when they call me or reply to my calls? Does anyone have an idea what the problem may be and how to correct it? As far as I know I am on the correct frequency because they can hear me. I just am not able to hear them On the local repeater I can receive just fine. I am heard and can hear. I have changed my antenna on the car from the "rubber ducky" to a magnet mount and when I checked the SWR on the magnet mount was 1.2:1. First time I ever mounted an antenna and did not have to set SWR it was that low just off the get go.
Bob Lampe, KF7ZGK, Kalispell, MT
I answered him: May be the problem is out of band strong RF signals in the new location, so they actually block your receiver front end, which is very sensitive but not selective in cheap hand-held transceivers...
- - - - - - - - - - - - - - - - - - - - - -
To solve this problem, I made myself a bandpass filter for 2 m band (145 MHz).
Now I can connect better antenna without receiving problem. This band-pass filter dramatically increase receiving performance! I can hits and listen repeaters up to 100 km away !
The details about my excellent home made Low-loss helical bandpass filter, click here
Here is the link of my YouTube video about this band-pass filter.
Here is the VIDEO of one Irish amateur radio enthusiast, Tony (EI5EM) who has made this filter, and shows us how efective it is.
Here is the LINK of another video from Romanian amateur radio enthusiast, Florin (YO3IVT) who has made this filter, and shows us how efective it is.
I Z33T home page I Z33T web pages in english I