[Mobile-Portable] IC706

[K0DAN]

----- Original Message ----- 
From: "K0DAN" <k0dan at comcast.net>
To: "Mobile-Portable Reflector" <mobile-portable at mailman.qth.net>
Sent: Wednesday, January 17, 2007 9:51 PM
Subject: Re: [Mobile-Portable] IC706


> If you have a NOAA weather station in your area (162.XXX MHZ), tune it in 
> frequency, then move 15 Khz, 30 Khz, etc. off. If NOAA has any strength, 
> you will be able to hear them (or at least the EFFECTS of their signal) on 
> your IF quite a ways off their center frequency. Theis is especially true 
> on the 706 and other rigs which are do-it-all rigs for hams. Nothing wrong 
> with the 706's, but they're designed to be all things to all hams, and in 
> the process there are inevitable trade-offs. Most of the time their 
> performance on VHF/UHF is great, but get them in a downtown urban 
> environment, and they're gonna get clobbered by intermod and other strong 
> signals which swamp their front ends. Same thing goes for working in a 
> contest or multi-station envrionment. This is not unique to the 706, lots 
> of receivers will get hurt on wideband modes such as FM.
>
> Avoiding the preamp will help. Trying the attenuator might help. But 
> depending on the S/N ratio of the station you're trying to hear, the 
> environment, antenna, and receiver front end may be your limiting factors.
>
> 73
>
> Dan
> K0DAN
>
> ----- Original Message ----- 
> From: "Gary Pearce KN4AQ" <kn4aq at arrl.net>
> To: "Mobile-Portable Reflector" <mobile-portable at mailman.qth.net>
> Sent: Wednesday, January 17, 2007 3:50 PM
> Subject: Re: [Mobile-Portable] IC706
>
>
>> At 02:59 PM 1/17/2007, you wrote:
>>>...
>>>Didn't have an attenuator handy to rule out the overload problem. Wasn't 
>>>using the preamp, of course. And was ignorant of the how to turn down the 
>>>RF gain (combo of RF gain/squelch is selectable and I didn't)
>>>73
>>>
>>>Larry K3VX
>>
>> The 706 has a 20 dB attenuator readily available - just hold down the 
>> "pre-amp" button for two seconds and you get the attenuator instead.
>>
>> The squelch/RF gain control can be set for "dual mode" - clockwise for 
>> squelch, counterclockwise for RF gain, with "straight up" being the 
>> dividing line.  You do that in the initial setup menu.  But that 
>> control's effect is fairly late in the process and may not do what you're 
>> looking for.
>>
>> Front-end overload from 3 miles away is unlikely.  And while the energy 
>> at 16 kHz may be minimal, most receiver's filters are not very sharp at 
>> 15 kHz.  The ARRL labs tested the 706 at 20 kHz and found the receiver to 
>> be 70 dB down at 20 kHz.  Alas, they didn't publish the slope from 15 to 
>> 20 kHz.  My guess is that the receiver is hearing pretty well at 16 or 
>> even 17 kHz, well in to the adjacent channel.  For comparison, my Yaesu 
>> 8900, generally a pretty good receiver for rejecting intermod, is poor at 
>> adjacent channel rejection at 20 kHz - only 58 dB down.  My on-air 
>> experience confirms it - I can hear some hash from strong, 20 kHz 
>> adjacent channel signals that the 706 doesn't hear.
>>
>> This being a contest, maybe some of the stations were punching the audio 
>> a little harder than usual, filling out that spectrum.
>>
>> 73,
>> Gary KN4AQ
>>
>>
>>
>>
>> ARVN: Amateur Radio//Video News
>> Gary Pearce KN4AQ
>> 508 Spencer Crest Ct.
>> Cary, NC 27513
>> kn4aq at arvidnews.com
>> 919-380-9944
>> www.ARVidNews.com
>>
>> ----
>> Your Moderator: Dick Flanagan K7VC, mobile-portable-owner at mailman.qth.net
>>
>
>