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Is there any need to replace saw filter on this comtech tuner module?

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Hi Thomas,

                          I just got hold of 2 used range video receivers.I tested these receivers by placing clode to my dragonlink antenna(at full power settings) but no interference at 1280 MHz. So i thought they must have been modded by D480 saw filter.But when i opened it,i found NM F480-2 and it looks like 21 or 27 MHz filter.

So wondering is it worth to swap the saw filter on these receivers?Please suggest.Thanks.

IMAG2449.jpg

IMAG2450.jpg

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If it has a 27MHz SAW filter then replacing it with the ECS-D480A filter will add a couple dB of gain. But be aware that removing the old filter is difficult. Some people that tried it caused some damage that reduced RF performance (or killed it). So don't attempt it unless you have strong PCB reword skills.

 

 

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Thanks Thomas.

I will first try flying long range and compare it with my existing RMRC comtech with saw filter already modified with D480A.If the difference is not much then i will leave it alone.

Regarding PCB rework,i am not that expert but i think i can handle this.I got Hakko desoldering vacuum gun which should help in case i need to replace.So far i have replaced main MCU on my frsky QX7 transmitter after i nuked it when accidentally i supplied trainer port with 5v and also some RAM chips on my VW diagnostics tool.

Are these SAW filters temperature sensitive?

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Are these SAW filters temperature sensitive?

Low risk for heat damage. The SAW construction is similar to a crystal oscillator and can take normal rework / soldering temperatures.

Besides the three pin legs, the bottom side of the filter is also soldered to the PCB. It takes a lot of heat to reflow this hidden region.

After fully desoldering the three legs with your Hakko vacuum tool, you can move on to the hard part. I suggest using two soldering irons, one on top of the SAW's metal case and another on the bottom of the PCB (on the copper area that is under the component's center area).  Apply extra flux and when the PCB is hot enough to reflow the hidden solder the SAW will come right out with a gentle pull. Don't force it, you don't want any PCB damage.

 

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Yes, be careful with the hot air. The nearby components may reflow; Then they can move off their pads while you wrestle with the SAW chip. That's exactly what happened to one guy that messed up his SAW chip upgrade.

 

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