[ICOM] Inrad filter mod for IC-765

[dmeitzen at comcast.net]

Thanks for taking the time.
Best Regards
Dave

-------------- Original message -------------- 
From: <paul at w8aef.com> 

> 1 KHz seems to be a little far off for not completeing the alignment when 
> replacing ssb filters. I would expect maybe 100 or 200 Hz would be closer 
> to normal. 
> 
> I believe the purpose of Inrad's alignment is to center the audio passband 
> into the filter passband. 
> 
> I don't remember the exact frequencies but as a for instance let's say they 
> are 300 Hz and 2.5 KHz for a 2.2 KHz ssb filter. 
> 
> You generate an audio tone at 300 Hz that would produce 50 watts out of the 
> radio (rf output control and maximum and into a dummy load). 
> 
> Then you generate a 2.5 KHz tone at the same level and observe the output 
> power. If it is 50 watts you are done. But if it is not then you adjust 
> the carrier oscillaor frequency such that the power output from the radio is 
> equal when you generate the 300 Hz and 2.5 KHz tones. 
> 
> And then do the same for the opposite sideband. 
> 
> The reason for using the audio generator and the 50 watts output is so that 
> receiver agc and transmitter alc will not mess you up. 
> 
> Then when you switch between sidebands the receiving station will (should) 
> hear the same audio response. 
> 
> And your dial frequency may or may not indicate your actual carrier 
> frequency. 
> 
> It's been 12 or 13 years since I did this so be sure and refer to the 
> instructions that came with your filter. 
> 
> My experience with the original Icom filters in my 765 was not good, but the 
> Inrad filters worked fine. 
> 
> de Paul, W8AEF 
> 
> ----- Original Message ----- 
> From: 
> To: "ICOM Reflector" 
> Sent: Sunday, January 08, 2006 10:09 PM 
> Subject: Re: [ICOM] Inrad filter mod for IC-765 
> 
> 
> Thanks for the answer. The question is if you do not do the alignment will 
> the unit seem to be off frequency to the receiving station? I have been 
> getting complaints that I am about 1Khz low? 
> Thanks 
> Dave 
> 
> -------------- Original message -------------- 
> From: 
> 
> > Not sure which filter mod you are talking about, but could it be 
> > installing 
> > Infrad filters and the subsequent alignment using an audio generator? 
> > 
> > I did that about 10 years ago to a 765 and it is a rather involved 
> > procedure. 
> > 
> > de Paul, W8AEF 
> 
> ---- 
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