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Quantro - reducing

This forum is for discussions regarding System Infrastructure and Related Equipment. This includes but is not limited to repeaters, base stations, consoles, voters, Voice over IP, system design and implementation, and other related topics.

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kb4mdz
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Quantro - reducing

Postby kb4mdz » Fri Aug 09, 2013 5:20 pm

I've seen a very few reference to running a Quantro at lower power, by taking one PA module out of service.

Anybody have any clues?

I've got a VHF Quantro, full 350 watt station, with the IPA & PA that look like they came out of an MSF5000, that I don't want to have to run full-bore. Is it truly as simple as taking out the final PA, & doing a little tuning?

desperado
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Re: Quantro - reducing

Postby desperado » Tue Aug 13, 2013 5:29 pm

The Exciter in a Quantro/Quantar are running all the time (transmitting) fire up a radio on the TX freq and hold it near the front of the radio... it will hear the carrier.
Might be able to get the 100Watt quantar powre supply and PA then be about to turn that down.
I assume that you are trying to duplex repeat on ham bands (narrow split on VHF) and can't find a duplexer that will work.

If that is the case, you don't have many options.
Keith
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kb4mdz
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Re: Quantro - reducing

Postby kb4mdz » Tue Aug 13, 2013 6:27 pm

No, I've got a 350 watt monster that I don't need; trying to just reduce the power to about 100 watts, on commercial/public safety freqs.

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kb4mdz
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Re: Quantro - reducing

Postby kb4mdz » Tue Aug 13, 2013 6:50 pm

Tho putting it on my local 2m machine's freq. & swapping it in place of the Vertex VXR5000, with a co-channel repeater just over 80 miles away....would be umm interesting.

n3obl
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Re: Quantro - reducing

Postby n3obl » Mon Apr 21, 2014 10:32 am

Just wondering if anyone made any progress with this project?

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kb4mdz
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Re: Quantro - reducing

Postby kb4mdz » Mon Apr 21, 2014 11:12 am

No, no progress. I can get the Quantro down to 175 Watts, and I've read some stuff about just using the driver &/or IPA, but other things have intervened, and it's pretty much a non-issue now.

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FMROB
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Re: Quantro - reducing

Postby FMROB » Mon Apr 21, 2014 1:32 pm

You have two MSF looking power amplifiers, correct.

If so, one is first stage and the other second stage from what I understand. Just disconnect the second stage unit and run the first stage, which if the unit was ordered as a 100watt repeater would have been the only one installed. Give it a try.

You are correct, they are the MFS amplifiers, and are bullet proof. I have been tearing down MSF's and quantros for the amps and using them on my DMR stuff for a few years now. They work and keep working. Heck, we've got a few here that have been in service for 15 years or so analog, and now in DMR service for a few years and haven't missed a beat. They mate up to the XPR8400 well, as you can run the power down on those units without an issue. I cant even keep a Quantar on the air for half that without having a failure of some sort, lol. We had gotten a few UHF 250 watt units a few years back and needed to do the same thing. I remember just removing the second stage and re wiring some of the internal rf cables, and good to go.

Rob

n3obl
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Re: Quantro - reducing

Postby n3obl » Mon Apr 21, 2014 7:57 pm

Well I got one here has a smaller heatsink up at top then the middle unit is a huge heatsink. I thought the upper unit is a IPA

George
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Re: Quantro - reducing

Postby George » Wed Apr 30, 2014 5:50 am

[quote="n3obl"]Well I got one here has a smaller heatsink up at top then the middle unit is a huge heatsink. I thought the upper unit is a IPA[/quote]

I guess no one has answered this one.

The upper smaller heat sink is a 25 watt PA.

The lower larger heat sink is the 350 watt PA.

You should be able to change out both of these units to a 100 watt PA. Look in your manual for the cabling configurations and make it look like the 100 watt station.

This really should not be a problem.

You can also get rid of one power supply and save your power bill some pain.

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redbeard
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Re: Quantro - reducing

Postby redbeard » Fri May 02, 2014 10:06 pm

I would be happy to remove the final 350W PA and just run off the driver PA, but how will the station act without the power control line from the final PA?
Look, it's not in my nature to be mysterious. But I can't talk about it and I can't talk about why.

loband
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Re: Quantro - reducing

Postby loband » Fri Jul 04, 2014 6:59 am

Why bother to own a high horse power machine only to run it at low power.....it brings a tear to my eye to even think about it......I'll give it a nice air conditiond home and run it at a cool 300watts. Hehe.

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kb4mdz
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Re: Quantro - reducing

Postby kb4mdz » Fri Jul 04, 2014 8:20 am

loband -

I see what you're saying, and I don't disagree with it. But I won't bore the thread with the long story, unless pressed.

Or I could just put a big ol' hi-power attenuator on the thing, like 3 dB at 200 Watts.

loband
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Re: Quantro - reducing

Postby loband » Sat Jul 05, 2014 7:47 am

I have a 25w vhf Quantar I will trade for a high horse power Quantro. All one has to do is drive it here.

loband
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Re: Quantro - reducing

Postby loband » Fri May 04, 2018 5:22 pm

Anybody have a working 350w PA deck they want to sell?

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motorola_otaku
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Re: Quantro - reducing

Postby motorola_otaku » Wed May 30, 2018 8:55 am

Y'all are overthinking this. :lol: If you want to run a dual-PA 350W Quantro at lower power just change the station type in RSS to the power level you want, and swap the PAs out with the appropriate power level PA from a MSF5000. Easy pleasey. You can even drop a PA stage and power supply in the process, and move into a smaller cabinet (not to mention vastly reduce your current consumption.)

Conversely you can buy one of the cheap 800 MHz Quantars off Ebay, plus a PA in the band/range you need, and convert it to a regular Quantar and get rid of all that old bulky MSF hardware.
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kb4mdz
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Re: Quantro - reducing

Postby kb4mdz » Wed May 30, 2018 10:43 am

Appreciate the input, but this thread is way old. We ended up using the Quantro as a development unit for some site monitoring. Also, turns out even at full 350 watts into a dummy load, it didn't draw but maybe 14 amps A/C; so I ran it temporary on a 15A NEMA plug, at reduced power (obviously even less) got happy.

Then instead of trying to shoehorn it into service, change licensing, probably have to upgrade coax & antenna, yadda, yadda, yadda and the thing - we ended up reselling in thru muni. gov. surplus channels, with the matching Sinclair duplexer, for more than the boss originally bought them for.

I know, I just depressed a whole bunch of you that have been drooling over it. Sorry!

loband
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Re: Quantro - reducing

Postby loband » Wed May 30, 2018 12:31 pm

What I would like to do is fool the station into thinking the 350w PA is still there, so I can run just the 20w driver to push a new Creshend rf amp. Does anyone know how to jumper the PA sense line?

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Doug
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Re: Quantro - reducing

Postby Doug » Wed May 30, 2018 3:31 pm

As strange as this sounds.... because the quantro sort of mirrors the msf5000 perhaps you can find what your searching for over on Repeater- Builder site. Under the msf station there was a brief description on bypassing the station amplifiers and driving a after market stuff.
I'm guessing it'll be a good starting point
Doug
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