Mostly I prefer HF CW for my SOTA activations, but am recently giving VHF a try as I can get into the large population centres of from Vancouver through to Seattle from our island.
In my neck of the woods (VE7/CL) many of the nearby summits have commercial radio towers on them. I have noted my el cheapo Wouxun UVD1P receiver got completely overloaded once from the local RF at one summit as to be almost unusable. Many years ago an older Kenwood handheld had similar problems when I activated from a large hilltop with commercial radio towers nearby (well before SOTA even began). At that time it was the priciest Kenwood handheld on the market.
I may have access to an older Motorola HT1250 handheld and wonder whether it might be worth reprogramming this for amateur frequencies - hoping they might be a bit more robust on the receiver front-end ??
Has anyone out there found a really good handheld that does not suffer so much from such problems?
Two thoughts for VHF/UHF on summits with lots of RF activity.
First - Hike to the summit then back down to the low end of the Activation Zone - being in the AZ but below the commercial/cell/ham repeaters may be all that you need to do. You will not get the 360 degree view and contacts, but you may be able to hear the stations calling you.
Second - Use a minimum antenna - the original rubber ducky that came with the HT rather than the extended rubber ducky. Less antenna will capture less RF interference. This is like using the attenuator on your HF rig. Save the roll-up j-pole for sites with no RF problems.
A surprising number of hams still use the old Radio Shack (Tandy) HTX-202.
The story that I heard was that they have a band-pass filter built into the radio to prevent modifications to allow out-of-band use.
The older the model, the more likely it is that it has a filter of some kind in the input circuitry. Those that advertise wide band coverage of the entire vhf uhf spectrum have very little filtering so are most susceptible to front end or mixer overload.
All that said, there are low pass filters on ebay with a cutoff around 180 mhz, have seen only SMA connectors on them, or there are home brew filter designs I have posted before, so you can use BNC or other connectors to suit your rig.
Some have found the FT817 survives the high VHF RF environment better than the HTs do. My ICom V85 survives better than most of the Yaesu general coverage rigs, but every batch of every radio in every marketplace appears to be slightly different so it is very difficult to draw conclusions with any certainty. The old icom mobile (IC22A and IC22S 10w) had helical filters in the front end which is far better than any HT I know of.
Another option is to use horizontal polarisation if you are doing HT-to_HT S2S contacts. That may give better signals on 146 and reduce the signal level from the QRM sources. Again, very difficult to generalise even from specific successes found here.
I can confirm the FT817 story. Quite recently I tried to make a 2m S2S QSO to another activator with my FT1XD, made a few calls but heard nothing back. After a while I connected the same handheld antenna to the front connector of my FT817 and had no problem making a contact. They told me that they heard me before with very good signal and wondered why I didn’t answer.
Same antenna, both 5W. Both radios are proven to work ok.
Needless to say, there is a huge comms tower and a number of smaller ones on that hill.
Reduce the attenuation either within the programming of the radio OR using a shorter antenna. Sometimes I will use a second handheld with a shorter antenna to “receive” and use my primary radio to transmit.
Use a nearby building to “block” the RF. Get on the side furthest side of the building away from the antennas. Get low to the ground.
In another thread, I posted about my search for the perfect 2m SOTA radio. Here is part of the info copied from that thread:
Rather than resort to a crummy antenna, I went with a better radio. I spent months testing various radios from friends on my bench for overload and intermod rejection. Discovered that the Icom IC-2A and the Radio Shack HTX-202 had the best receivers of all, including new HTs.
I bought a few mint condition of each and set about making them 100% before going to any summits. I have been to several densely populated tower sites with them (I work in broadcasting, so I am at a tower almost every day) and confirmed that the Radio Shack HTX-202 and the Icom IC-2A have no trouble even in the strongest fields with other VHF gear.
Nothing worse that hearing someone call “CQ SOTA” over and over and them not hearing the dozens of stations trying to come back to them on their Baofeng HT!
Good question VE7EA.
I know my Yaesu FT1DR gets clobbered on Cadillac Mountain in Acadia NP in Maine. There must be a NOAA Wx transmitter nearby because my radio gets hammered every time. I’m sure using an Arrow antenna doesn’t help any.
Interesting to see the old school HT’s perform better in this regard.
With limited VHF/UHF experience during SOTA activations I have found the Baofeng UV-5RV2, with stock antenna, to be easily de-sensed on 2 meters. On the same summits my 1983 vintage Icom IC-2AT appears to work normally with either a 19" telescoping whip or an Ed Fong rollable J-pole.
These summits are line of sight to Mt Wilson where much of Los Angeles broadcast infrastructure is located.
The Baofeng appears to work ok on 70 cm fm.
Almost ANYTHING beats hearing “CQ SOTA” over and over on 146.520 and people answering the CQ’s as the CQer steps on them calling CQ again. And again. And again. Then, when someone is finally close enough or strong enough to overcome the receive desense and make contact, they don’t even bother to tell the CQer that there are others trying to make contact but they have trash for a radio and don’t hear all of them. Frustrating!
It’s almost always a Baofeng or similar. The “I’m just going to try SOTA with my cheapo radio” does more that simply discourage new people doing SOTA, it also clogs up the frequency when you have multiple activations going on.
I’ve owned a few budget HTs and find that some have nice features and are pretty good for general use but they tend toward deafness once away from nearby repeaters. Published receive sensitivity specs on the budget HTs are lower than those from the higher end manufacturers and in real life this makes the difference between receiving a signal or nothing at all.
I’ve had great luck with Yaesu’s VX-6R. The front end seems a bit tighter than that of my IC-V86, another good reliable radio, although I only notice noise when using a directional antenna in some RFI-intensive environments.
Having been a perpetrator of this myself, I can tell you that even my Yaesu FT2DR has this same problem. One of the worst culprits for blowing out the attenuator are the NOAA weather broadcast stations on 162 Mhz. They must be super high-powered and splatter all over.
I’m guilty of calling CQ SOTA over and over and not hearing anyone because I was being drowned out by an FM transmitter. I tried activating Blue Mountain, W4V/SH-030 this Spring and couldn’t hear a thing due to the S9+ noise my Yaesu VX-7r was picking up. I now have an FM Broadcast filter and will either use that or HF on my next attempt. The same HT worked fine at a peak on Skyline Drive, both as an activator and ad hoc chaser.
I activated W4C/WM-001 a few days ago with my FT3DR and a retractable half wave. For a couple seconds, I actually heard the NOAA station come over my HT with VFO set to 146.520. Then moments later I made a 126mi contact with the same HT, which alleviated that concern significantly.
I thought for certain I was going to get drowned out now and then when I bought that HT, but I’ve had good luck with my FT3DR in noisy areas.