Adding a Second Receiver to a MSF 5000

[krazybob]

I really enjoy the excellent users here n come here again looking for advice.

We have learned some hard lessons with our MSF 5000's. Our club owns three. They are clearly great repeaters but just can't handle southern California 15KHz band plan spacing. We don't need to go there. The key two things that keep us from excellent receive are the fact that the channel spacing of a MSF is 30KHz, and designed as a multi-channel remote base they have a 2MHz receive window at full rated specifications. The MSF is unable reject the output of two repeaters placed on opposite sides of our input. It isn't their fault. The MSF is sucking their signals in and everything within 2MHz. Our Angle Linear dual band pass cavities knock that down to a still unacceptable minimum of 1MHz without doing anything to keep Catalina and Victorville out of our input +/- 15KHz. We tried the 15KHz crystal replacement kit with miserable audio results. Effectively narrow banding the MSF was not the solution.

Our remaining solution is to replace the MSF's receiver. The MTR2000 was a thought but it too is for 25KHz band plan spacing. We need a single frequency receiver that can be peak tuned but honestly don't know enough as repeater owners to know what choices we might have. Something with a preselector or helical resonator on the front-end would be great. Deciding that our choice might be a new design Motorola mobile like a CDM750, which appears to have a good front-end, augmented with a yet to be located Micor helical resonator, we believe that we can breathe new life into our MSF's. Can a CDM750 handle the environment? We don't know but have seen numerous repeaters built using mobiles and with native 20KHz channel spacing might be as close as we can come.

But how to interface it. We have read every document that we can find without success. We remain open to options. The MSF is still a workable repeater. We're just admitting that we know that we can do better. We've talked a great deal with Robert, WA1MIK, and this is the best that we can come up with. Any suggestions?

[escomm]

Our remaining solution is to replace the MSF's receiver. The MTR2000 was a thought but it too is for 25KHz band plan spacing.

No, no it's not.

[Bill_G]

The real solution is so obvious.

[d119]

This discussion is over. It's been hashed out in six separate threads already.

Bob: You need to get a different frequency pair, not a different radio. Please stop creating new discussion threads about this problem, we're starting to get weary of it.

[wavetar]

This discussion is over. It's been hashed out in six separate threads already.

Bob: You need to get a different frequency pair, not a different radio. Please stop creating new discussion threads about this problem, we're starting to get weary of it.

Agreed. If you come here looking for advice, being selective over which good advice you choose to follow is counter productive to your cause. You need a new frequency pair, there is no radio receiver or filtering combination that can do what you need. Even of you managed to notch out the offending frequency, at 15KHz away from yours, you'll knock your receive down 20-30dB, completely eradicating any benefit you perceive it'll give you.