Re: UV-5R SOTA in high levels of RF


Paul Butzi (W7PFB)
 

My cousin Curt K7ZOO is pretty active with SOTA in Arizona (among his other interesting projects is a plan to do summit to summit SOTA using heliographs).

His experience is that he is often able to hear stations on his Yaesu handheld that cannot be heard on SOTA partner's Baofeng UV-5r.  This is on summits that are in the middle of nowhere, so there are no other transmitters within miles.

Caveat: while it’s likely true that all FT-60’s perform alike, or that all Kenwood TH-F6a’s perform alike, it is most definitely not the case that all Baofeng UV-5r’s will perform alike, because of variations over time in which compromises are made for one particular batch of UV-5R radios.

An interesting article on building a bandpass filter is at https://www.arrl.org/files/file/Technology/Intermod/No_Tune_Filter.pdf

Note that both the filter described in the article and the SOTABEAMS filter have 3db of insertion loss, meaning that unless you get the filter out of your antenna feed when you transmit, the filter is eating half of the power and your 5 watt radio is effectively a 2.5W radio.

All very interesting stuff!

-p W7PFB
73, Don’t forget to smile and have fun!

On Feb 19, 2022, at 12:07 AM, Dan Pflugrath <dpflugrath@...> wrote:

Referencing Ken's (W7ECK) post and video about the Boafeng UV-5R handheld operating on summit with commercial RF transmitters and towers.
 
An easy way to check out your radio in a high RF environment is a drive up SOTA summit like Little Mountain W7W/SK-173  just south of Mt. Vernon.  I had the same RF overload experience there with my Baofeng UV-5R.  I generally do not have the problem with RF swamping my UV-5R by staying away from the antennas but still staying inside the activation zone.  It can even affect your HF operations.
For anyone that wants to operate "any" handheld radio in a high RF level environment (like Tiger Mtn. or Little Mtn.) you can purchase a 2 meter band pass filter from SOTABeams.  Even with the best Yasue, Kenwood etc radios the SOTA operators say the improvement is amazing with the bad pass filter.  All 2 meter radios are affected to some degree.   https://www.sotabeams.co.uk/bandpass-filter-for-2m/  I am not aware of anyone using this filter with a UV-5R.
 
If someone has one of these 2 meter band pass filters would you run some tests on a High level of RF  summit with various radios including the UV-5R to verify the performance with and without the filter.  Cougar mountain would also be a good place to run the tests but Little Mountain does not require a pass code access and Tiger is a good hike.
 
73 Dan KA7GPP
 

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