I've been following this with interest for a while as we have an Icom in HI
and have almost exactly the same problems - sometimes we can hear / be heard
---From a good distance away but on occasions, we can't hear Rochester until we
are within about 5 miles of them (122.25Mhz).
As far as I can see, the problem must be one of three things:
1) the aerials gain isn't over the required range - this could easily be
fixed by a more conventional aviation aerial
2) The squelch is either over enthusiastic or being triggered by noise
---From the engine, GPS etc (anyone found any links here - I believe it may be
noise from the engine electrics as the radio 'deafness' seems less
pronounced when the throttle is closed.
3) The design or manufacture of the radio isn't 'as it says on the
box' - which I doubt from a name like Icom.
My theory is number 2 above - anyone got any ideas on this? (my limited
understanding of the Rotax history is that there are 2 types of ignition
unit in use - could it help if those with the same problem told us what
engine they have and what ignition units are installed - this problem seems
to be very widespread (we thought we were just unlucky and needed a new
aerial).
Peter
----- Original Message -----
From: "Bryan Allsop" <bryan@blackballclub.com>
Subject: Re: Europa-List: Radio reception problems
> <bryan@blackballclub.com>
>
> Thanks for your response Fred.
>
> I confess though that I am not sure that I understand all of it. Age is
> beginning to effect the clarity of my thinking processes, perhaps in the
> same way that my six year old Icom A 200 is not so clear in extreme
> circumstances.
>
> I began to lose the thread with the 'wild geese' and 'turkeys', and
> something to do with 'doorstops'. I must also confess that I am not
> totally
> up to speed with 'Genave Alpha 360's either, and I am even a little rusty
> on
> 'general azimuth'. Other than that, I think I am almost quite clear about
> what you are saying.
>
> So, what can I do Fred? Can I chop a bit off somewhere, or do I need a new
> radio?
>
> Incidentally, friends have noticed that the transmit performance drops off
> when the European Safety Com frequency 135.475MHz is used.
>
> Regards.. Bryan
>
> ----- Original Message -----
> From: "Fred Fillinger" <n3eu@comcast.net>
> To: <europa-list@matronics.com>
> Subject: Re: Europa-List: Radio reception problems
>
>
>>
>> <bryan@blackballclub.com>
>>>
>>> They were receiving me strength five, but for much
>>> of the transit I could not hear them at all.
>>>
>> Antennas work by the rule of reciprocity, and above indicates antenna
>> is not the problem, at least in that azimuth of the 360-deg pattern.
>>
>>> In both cases I have been able to hear other
>>> aircraft speaking to them strength five,
>>
>> If you can't hear a ground station, but other A/C yes, and they're not
>> in the same general azimuth, the radiating pattern of the antenna is
>> suspect -- an installation location problem. A/C to A/C doesn't have
>> the line-of-sight problem like A/C to ground over terrain. But the
>> ground station can achieve a near perfect antenna, canceling out the
>> line-of-sight issue.
>>
>>> I can now see that I have a common problem at the lower frequencies,
>>
>> Receive problems on the extremes of the bands indicate alignment
>> problems, but radios just don't go out of alignment to any significant
>> degree, if at all. The degree of problem you report suggests a
>> component might be way off spec. Low odds, but people hit lotteries.
>> Also, radiating pattern problems can be frequency dependent to some
>> degree.
>>
>> Hope this helps rather than chases wild geese!
>>
>> BTW, we can't deduce strength five or strength anything from what is
>> heard, unless rather weak. Leveling circuitry in modern radios +
>> other factors. Our old control tower was even handing "strength
>> three" or "four" to people. Must have an S-meter I figure. But first
>> visit to the tower, I alarmingly saw they used a Genave Alpha 360, a
>> "doorstop" in alternative use. No S-meter, but that turkey of a radio
>> could actually hint at strength reasonably well.
>>
>> Reg,
>> Fred F.
>>
>>
>>
>
>
>
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