ICOM 621-2-TR: Squelch Level and CTCSS

[rhombus_000]

I have an ICOM 621-2-TR running conventional UHF in the business band. It transmits fine, but on receive it seems very insensitive. Even with the monitor button on, it only picks up very strong signals. I have tested the antenna (1/4gp) with and adapter to a HT and the antenna is fine.

My question is this: does the squelch setting (currently 90) affect the decoding of CTCSS? Will the unit break squelch if the signal is below the threshold but the correct CTCSS tone is present? Or will a high squelch setting lock receive out even if the unit hears the right tone?

I suspect I may have a hardware problem since the unit is being outperformed by 4 watt HTs. The setting is in an industrial facility, HT's can talk to one another everywhere but the 621 only hears transmissions from outside.

Thanks in advance for any help...

 

[12dbsinad]

What you describe sounds like a bad Ceramic filter. I'm willing to bet the radio is a 07-08. VERY common in 621's of that time frame as they had a run of defective filters, and will cause very poor RX to the point of unusable. It is for sure fixable but requires some de-soldering/soldering skill.

 

[rhombus_000]

What you describe sounds like a bad Ceramic filter. I'm willing to bet the radio is a 07-08. VERY common in 621's of that time frame as they had a run of defective filters, and will cause very poor RX to the point of unusable. It is for sure fixable but requires some de-soldering/soldering skill.

Thanks for the info!!! I am pretty good at soldering I dabble in making my own PCBs, although I'm guessing that the filter is going to be surface mounted which will be a challenge.

Would you happen to have any info that could help me identify it's location on the board?

 

[12dbsinad]

I am going by my shear memory here, but I believe the common issue is in the 2nd IF (F12) on the board, this should be the location of the ceramic filter. You can download the service manual easily by doing a google search.

 

[rhombus_000]

I am going by my shear memory here, but I believe the common issue is in the 2nd IF (F12) on the board, this should be the location of the ceramic filter. You can download the service manual easily by doing a google search.

Thanks!!! I read somewhere else also that the 2nd IF 450 khz filter can be an issue. Got the unit apart and the filter seems moderately easy to get at aside from having to desolder a few connections to get the board out of the case.

Much appreciate the help, my company's radio budget is pretty much zero so it's either fix it myself or off to the scrap heap.

 

[jeatock]

Bad filters is an issue across all manufacturers, something that has become more of an issue since narrow banding.

A working, properly aligned Icom will have an outstanding front end. That is the basis for the company's success. A deaf Icom is broken.

Any of the Icom factory repair locations do a fine job for a flat hundred bucks, including return shipping in a week or less. Some will provide a pre-paid label for the next one. They see them every day (read as experienced), will diagnose and repair all the defective components, and also align the radio. Alignment is not difficult, but getting it right takes both time and bench equipment. I am a dealer and let AJR in Chicago do all my heavy lifting when it comes to repairs of the minuscule surface-mounted components. I suspect some of their techs moonlight as laproscopic brain surgeons --- components are that small and heat sensitive.