[ICOM] 746

[Gary Fiber]

Sorry did not give a real good answer. You are right the received signal either is not present or severely attenuated. One the one I remember seeing the signal was restored we the filter was lifted a bit. This happened mostly on the 455 KHz filters with the nuts on the bottom. In most of Icom's radios the big filters use a springy clip to hold them in place. Sometimes the end user also lifted the circuit board, and used the supplied nuts to Aldo hold the filter. As most of us tend to do we tighten nuts on studs down nice and tight, so tight the filter case shorts the signal connections to chassis and the signal goes away.

Gary P. Fiber K8IZ
gfiber1952 at gmail.com
gfiber at comcast.net




> On Jan 31, 2016, at 10:05 AM, Kelly Taylor <ve4xt at mymts.net> wrote:
> 
> Hi Gary,
> 
> I don't dispute the Icom tech theory, but what is the usual occurrence when a signal path is shorted to ground? It dies, no?
> 
> OP reported not a dead radio when the filter was selected, but zero change in operating parameters. No change in bandwidth, but still receiving as if no filter change had been enacted. 
> 
> K
> 
> Sent from my iPhone
> 
>> On Jan 31, 2016, at 9:58 AM, Gary Fiber <gfiber at comcast.net> wrote:
>> 
>> The techs at Icom found at times a filter was to tightly pressed into place. The filter case was shorting the actual in /out connections to ground. Pulling the filter out just a little solved the trouble. A more permanent repair was to insulate the bottom of the filter case. This did not happen on all radios but a few we saw this. 
>> 
>> I have been gone from Icom for coming onto 15 years so tech things are fading a bit these days. 
>> 
>> Gary P. Fiber 
>> gfiber1952 at gmail.com
>> gfiber at comcast.net
>> 
>> 
>> 
>> 
>>> On Jan 31, 2016, at 9:40 AM, Kelly Taylor <ve4xt at mymts.net> wrote:
>>> 
>>> Wouldn't a bad or shorted filter make the radio sound dead? I tend to go with the reset-turned-off-filter-settings theory. 
>>> 
>>> Kelly
>>> ve4xt 
>>> 
>>> Sent from my iPhone
>>> 
>>>> On Jan 30, 2016, at 3:24 PM, Gary Fiber <gfiber at comcast.net> wrote:
>>>> 
>>>> You might also just gently pull up on the filter. I have seen the filter case short to the mounting holes. Sometimes placing some electrical tape on the filter bottom will prevent it from happening. Could also be a filter that has gone bad.
>>>> 
>>>> Gary P. Fiber K8IZ
>>>> gfiber1952 at gmail.com
>>>> gfiber at comcast.net
>>>> 
>>>> 
>>>> 
>>>> 
>>>>> On Jan 30, 2016, at 2:10 PM, Lloyd Curry <lloyd.na4d at gmail.com> wrote:
>>>>> 
>>>>> I have an original Icom 746 (non-pro) with the 500 hz cw filter. The
>>>>> filter has stopped working. When I push in the filter button the "nar"
>>>>> appears on the screen but there is no change in the audio or bandwith.
>>>>> Any ideas?
>>>>> 
>>>>> -- 
>>>>> Lloyd C. Curry
>>>>> Amateur Radio NA4D
>>>>> Greensburg, KY
>>>>> 
>>>>> I'm so nice I wish I had a friend just like me.
>>>>> ----
>>>>> Your Moderator: Dick Flanagan K7VC: icom-owner at mailman.qth.net
>>>>> Icom Users Net: Sundays, 1700Z, 14.316 MHz
>>>>> Icom FAQ: http://www.qsl.net/icom/
>>>>> To support QSL/QTH.net: http://www.qsl.net/donate.html
>>>> ----
>>>> Your Moderator: Dick Flanagan K7VC: icom-owner at mailman.qth.net
>>>> Icom Users Net: Sundays, 1700Z, 14.316 MHz
>>>> Icom FAQ: http://www.qsl.net/icom/
>>>> To support QSL/QTH.net: http://www.qsl.net/donate.html
>>> ----
>>> Your Moderator: Dick Flanagan K7VC: icom-owner at mailman.qth.net
>>> Icom Users Net: Sundays, 1700Z, 14.316 MHz
>>> Icom FAQ: http://www.qsl.net/icom/
>>> To support QSL/QTH.net: http://www.qsl.net/donate.html
>> ----
>> Your Moderator: Dick Flanagan K7VC: icom-owner at mailman.qth.net
>> Icom Users Net: Sundays, 1700Z, 14.316 MHz
>> Icom FAQ: http://www.qsl.net/icom/
>> To support QSL/QTH.net: http://www.qsl.net/donate.html
> ----
> Your Moderator: Dick Flanagan K7VC: icom-owner at mailman.qth.net
> Icom Users Net: Sundays, 1700Z, 14.316 MHz
> Icom FAQ: http://www.qsl.net/icom/
> To support QSL/QTH.net: http://www.qsl.net/donate.html