InterceptRadio.com Forums

For those that have experience with say the Icom F5121 radio (or any commerical mobile) are they (generally) less prone to overload than say the 2m ham mobiles? My Icom V8000 does a decent job but the squelch breaks open quite a bit on random noise. After doing research on other ham rigs, it looks like all of them generally suffer from this problem.

Do commerical mobile radios suffer from this problem too? I noticed the Icom F5121 doesn't have a squelch dial so they must use a digital squelch..? Is it worth upgrading to a commerical mobile rig? The difference in pricing is substantial (i.e. a commerical 2-way for the price of a ham dual-band mobile)

Nick,

At one point I had a V8000 (2 meter only) and IC-2720 (dual band) both mounted in the same vehicle. What I found was, the 2720 was extremely prone to intermod etc, whereas the V8000 was comparatively much "tighter" at the front end.

One reason for this is the fact that the "front end" of today's dual bands (regardless of manufacturer) are basically wide open, whereas the front ends of single bands are much "tighter".

I also compared a V8000 to the less expensive IC-2100, and found in that case that the V8000 was still "tighter". Truthfully, I found it to be one of the better HAM radios I have ever had, and really regret trading for who knows what I got on that deal!

The commercial rigs have a fixed squelch setting that is programmed in software. There are "front panel" options available to adjust it, but generally I think what you see there is those radios have a squelch that is "fixed" at a much tighter threshold than what we as HAMs would normally run.

The plus of this is less annoying noise.

The minus of this is reduced effective sensitivity - you don't hear weak signals as well.

If you want to "hotrod" that V8000, I have a limited supply of plug in DSP modules that can be plugged into the V8000 that will virtually eliminate noise.

PM if you want more info.

73,
Nick

Generally the commercial stuff with the exception of the low tier stuff (m1225 and other brands) will have a better front end and have sensitivity extremely close to the ham gear Ive tested but with much better selectivity. From the factory a CDM 1250 will have a receive sensitivity better than .3uv @12db sinad, open squelch around .18uv and not have near as bad a problem with front end overload as non commercial or even low tier commercial stuff.

One of the tuning procedures for these radios is to adjust the front end softpots. These are adjusted for the entire frequency band of the radio and dynamically adjust as the frequency is changed.

These also have better filtering on the power supply to the radio. Alternator noise if present is knocked down quite well as compared to say an M1225 without such filtering or most of the ham gear Ive run and worked on in the past.

If I drive up on Tiger or Gold mt... Ill get some front end overload once in a while but not too bad. But other than that no problem on any band I have.

_________________
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Yeah I was comparing the specs between the V8000 and the F5121 and the V8000 and they seem very similar. The built-in TXCO is of higher grade and the audio output is doubled (4w versus 2w.) The nice thing is that the F5121 looks to be using the same bracket as the V8000. This would make swappings radios pretty simple.

If the radios are the same width, they are indeed the same bracket.
ICOM has used 3 different widths (and therefore 3 different brackets) for the HAM / LM mobile radio bodies.