Batboard

We have switched over Min v to narrow band VHF. The system has a UHF link wide band interfaced to a VHFnarrow band radio that passes the audio.. Problem is that the tones go off but the audio is terrible, this happens when tone is sent via the UHF or internally generated in the vhf radio. DEVIATION IS 1.7 TO 2.0 KHZ. Any ideas.

When listerning on a vhf radio, the audio sound very good ???

Thanks.

JD wrote:We have switched over Min v to narrow band VHF. The system has a UHF link wide band interfaced to a VHFnarrow band radio that passes the audio.. Problem is that the tones go off but the audio is terrible, this happens when tone is sent via the UHF or internally generated in the vhf radio. DEVIATION IS 1.7 TO 2.0 KHZ. Any ideas.

When listerning on a vhf radio, the audio sound very good ???

Thanks.

Am I understanding you correctly, it is just the Minitor V that has the poor audio?

If that is the case were the pagers used before this on the same system in wide band with no issues?

Have you switched the pager back to wide band? If not try that and see if the audio improves.

Is it just your pager, or all of them that sound bad?

If it is just one pager, and only in narrow then the receiver has an issue. The Minitor V should be worked on in a shop that can maintain the pager's I.S. rating, but I would just send it to the depot if it does have an issue.

Good luck with it.


Jim

They ARE ALL THAT WAY, ABOT 40 OF THEM

Sounds like over deviation of audio. Did the person that did the setup have proper test equipment? They will need 2 service monitors, or one that is capable of duplex operation.

Are there PL tones involved? or carrier squelch?

Should be no issue going wide to narrow in a cross band setup (we do it). Just a matter of setting levels.

With a 1 kHz tone, injecting 60% deviation on wideband (3 kHz) should equal 60% deviation on narrow band (1.5 kHz). Watch for clipping and distortion. Do an audio sweep and look for significant roll off.

Make sure you can get close to your full 2.5 kHz deviation on the narrowband radio.

Check you paging tones and try to get around 2 kHz deviation.

Should sound as good as wideband.

Is the base radio using Hear Clear, or nay compandering or Expansion?

Thanks, I am using Kenwood radios, found out today that Kenwood , when going to NB , you have to re align the radios , do not come from factory aligned for NB.. Would this be an issue with CDM 1250 radios ?. Glad to hear that wide to narrow is working. I use a HP8920a monitor, VHF NB radio shows 1.7 to 2.1 Deviation, ???? All worked great, but as sson as I went to NB on VHF, wow.

NO compandered or hear clear involved.

Yet another reason Motorola has single contracts that are larger than Kenwood's annual LMR sales

They nip at the heels for a reason

Just curious what Kenwood radios your using?

I kind of find that hard to believe their not narrowband ready.

TK 8180 UHF aand TK 7180 VHF.. County wide dispatch system does not have a set plan yet, rumor they have to get money in budget for equipment.


RF GUy , thanks for the info. Dev is around 2.o on tones. Again called Kenwood, they are suspecting the wide UHF signal is causing the problem, they are not sure. I am going to try a CDM configuration and see how the audio sound.

Thanks guys for taking the time to answer my questions.

Sounds like to me their talking to some salesman at Motorola that wants to make their shops quota for the year in sales.

We run KW's, we're on NB and we have no issues. So I highly doubt that KW's are the blame for this.