R1225 hidden RX setting

[kk6rq]

I find myself having to refresh myself about the hidden RXFE setting on the R1225 repeater. You highlight the RX
freq, then do Shift-F3 and you get:
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RXFE Select

*High - *Medium - *Low
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
"Selects the band pass filter for optimizing the
tuning of the receiver front end."
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Question:
What I can't remember is whether it adjusts SENSITIVITY or ATTENUATION or RANGE. If I had it in front of me I'd answer the question
myself w/ the service monitor, but it's not right now, so I can't.

Anybody remember this? Thanks.

Bob

[Bill_G]

Wasn't aware of this feature, but if it truely is a Bp filter, and the choices are high, med, and low, then that suggest freq ranges of the model. I don't know if the limits of the Bp are published, or how much they overlap.

[Al]

According to the R1225 service manual, the receiver's front end has 3 pin diode switched bandpass filters following the first RF amp. All three have 1 dB bandwidths of 10 Mhz, centered on 151, 161, and 171 Mhz. So the first filter covers 146-156, second 156-165 and the third 165-174 Mhz. The hidden setting appears to allow override of automatic(by the RSS) selection of the correct Bp filter which likely would be chosen based on the Rx frequency. The UHF model is similar, with Bp filter ranges of 444-454 Mhz, 454-464 Mhz, and 464-474 Mhz.

[Bill_G]

Thanks Al. sounds like real Bp window filters to me. I see no reason why someone would manually change the Bp setting except as a bench test.

[Al]

Agreed, Bill. It's hard to imagine a situation where the RSS/codeplug selection wouldn't be optimum.