[ICOM] Icom 730 LSB OSC question

Wed Jul 10 21:02:42 EDT 2013

Hi Ken,

I am a little confused now. You're putting the FL-44A back in? I thought you took out the stock mechanical filter (MF-455-11GZ) and replaced it with the optional FL-44A.

Maybe you're just referring to the 455 kHz filter as "the FL-44" as a generic term? The two filters are definitely different. The Kokusai MF-455-11GZ mechanical filter is the stock filter which comes with the radio, the ICOM FL-44A is an optional upgrade.

Please let us know your progress and good luck!

73, Frank W3UHF

On Jul 10, 2013, at 8:53 PM, Ken wrote:

> Ok,  All I am going to do is swap the old FL-44 filter back in.  Pretty easy to do.  Receive sounds almost OK  if I slide the receive IF shift off to the right.  I'll let you know how it turns out.
> 
> Ken
> 
> 
> On 07/10/2013 07:14 PM, Frank A. Ellis wrote:
>> OK that's better. I was thinking you had done something with the FL-30 in the 9 MHz IF. That's the filter I have had problems with before.
>> 
>> The symptom can be observed with just white noise. With the IF shift centered, the tonal quality of the white noise should be roughly the same in LSB and USB. My first FL-30 failure manifested itself by one sideband sounding tinny, and the other was too bassy when switching between LSB and USB with the IF shift centered. I could readjust the IF shift off center about a quarter inch, and find a sweet spot where both sidebands would sound the same again, switching back and forth. I estimated the offset was between 200 and 300 Hz.
>> 
>> I checked the BFO's, which were both right on. Then checked the alignment of the IF shift, which was also good. The problem was staring at me but I couldn't face the fact that the FL-30 had shifted frequency, causing the passband shift that I observed. When I replaced it, all was back to normal.
>> 
>> I had three different radios do the same thing over a many-year period and in each case the FL-30 was the culprit. I confirmed all the bad filters by transplanting them into good radios to verify they were bad. In each case the filter had shifted upwards a few hundred Hz.
>> 
>> Of course, you have been working with the 455 kHz IF and not the 9 MHz. Whole different problem there. Just wanted to pass this along for general info.
>> 
>> Sounds like your problem started with the FL-44 swap, and that's a good place to go back to.
>> 
>> BTW, the stock mechanical filter in the IC-730 455 kHz IF is pretty good. If I was going to install an option filter in a stock 730, I would pick the 9 MHz IF (FL-30) to install first.
>> 
>> 73, Frank W3UHF
>> 
>> 
>> 
>> On Jul 10, 2013, at 7:58 PM, Ken wrote:
>> 
>>> Frank,
>>>  Yes, thinking back, it all started with the FL-44 swap...  hmm... Its hot here, work on my tractor till 11:00 or so and hide back in the house.  Swap the filter out and see if it fixes it.
>>> 
>>> Ken
>>> 
>>> 
>>> On 07/10/2013 06:49 PM, Frank A. Ellis wrote:
>>>> Hi Ken,
>>>> 
>>>> Got mine in 1984 as well!
>>>> 
>>>> What was the reason for changing the FL-30? Maybe I missed something. Did the problem start since the replacement filter was installed?
>>>> 
>>>> 73 Frank W3UHF
>>>> 
>>>> 
>>>> 
>>>> On Jul 10, 2013, at 7:05 PM, Ken wrote:
>>>> 
>>>>> Frank,
>>>>> Ok, maybe thats the problem, I changed the FL-30.  I have had my 730 since 1984, so its 30 years old....I have the old one, maybe I'll just swap it back?
>>>>> 
>>>>> 73, Ken
>>>>> On 07/10/2013 05:54 PM, Frank A. Ellis wrote:
>>>>>> Ken,
>>>>>> 
>>>>>> Check the BFO oscillator frequency and also the alignment of the IF Shift. When the BFO oscillators are on frequency and the IF shift alignment is correct, the radio's AF should sound approximately the same on LSB as it does in USB with the IF Shift centered.
>>>>>> 
>>>>>> If not, one of the sections of the FL-30 (if installed) may have shifted in frequency. I have had 3 FL-30's do this over the last 25 years or so.
>>>>>> 
>>>>>> Still have my IC-730 after almost 30 years!
>>>>>> 
>>>>>> 73, Frank W3UHF
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> On Jul 10, 2013, at 6:28 PM, Ken wrote:
>>>>>> 
>>>>>>>   Ok, I have a Icom 730 that has some how moved the passband higher in frequency.  I have the manual and think I know what to tweak, just wanted to check if anyone else has adjusted it?  I can hear it on receive, I should be able to adjust it by ear to get it back,  USB is correct.
>>>>>>> 
>>>>>>> Tnax, Ken
>>>>>>> ----
>>>>>>> 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/
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>>>>>> 
>>>>>> ----
>>>>>> 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
>> 
> 
> ----
> 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