VHF Quantar Duplexer 600KHz?

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.

Moderator: Queue Moderator

Post Reply
User avatar
escomm
Queue Moderator
Posts: 5168
Joined: Fri Mar 24, 2006 8:24 pm

VHF Quantar Duplexer 600KHz?

Post by escomm »

Manual says something like 200KHz of bandwidth at 1.5MHz separation and 600KHz of bandwidth at 2.5MHz separation. Has anyone used them on a 600KHz split and how was the insertion loss and other performance?
User avatar
chartofmaryland
Batboard $upporter
Posts: 411
Joined: Sat Dec 28, 2002 11:25 pm
What radios do you own?: Alot

Re: VHF Quantar Duplexer 600KHz?

Post by chartofmaryland »

Afternoon Escomm,

When you are speaking of the bandwidth, are you asking about the bandpass bandwidth of the high and low side of the duplexer?

The minimum seperation between transmit and receive frequencies will always stay at 1.5 Mhz Tx to Rx or 2.5 Mhz Tx to Rx.

The flat pack duplexer from Fingu is lacking the Q to perform at 600 Khz Tx to Rx frequency spacing.

We have tuned a few to try and the best we could run with around 2 dbm desense was 3 watts on transmit while still getting -119 dbm on receive.

CoM
If the lights are out when you leave the station and then come on the second you key up, you know you have enough power.
User avatar
escomm
Queue Moderator
Posts: 5168
Joined: Fri Mar 24, 2006 8:24 pm

Re: VHF Quantar Duplexer 600KHz?

Post by escomm »

Sorry I was talking about the rack mount one. I think the current part number is 9175300H02
User avatar
Astro Spectra
Posts: 655
Joined: Sat Sep 22, 2001 4:00 pm

Re: VHF Quantar Duplexer 600kHz?

Post by Astro Spectra »

Hi escomm, that set of cans has a minimum t to r split of about 1.2 MHz. It's a bandpass-bandpass design. At the narrowest spacing the pass band is about 100 kHz aside , meaning the width of the high and low pass bands.

It's not big enough really for the ham split, you need something with 'more can' i.e. larger cavities. My favourite is the Sinclair Q2220. My other favourite is Nobu at Ceasers :)
User avatar
escomm
Queue Moderator
Posts: 5168
Joined: Fri Mar 24, 2006 8:24 pm

Re: VHF Quantar Duplexer 600KHz?

Post by escomm »

Holy crap, that thing is not BP/BR???
User avatar
Astro Spectra
Posts: 655
Joined: Sat Sep 22, 2001 4:00 pm

Re: VHF Quantar Duplexer 600KHz?

Post by Astro Spectra »

There is a notch set by the a small tuning cap but from memory it's shallow at only 30 to 40 dB at the narrow splits, deeper at the wide splits. Because the main elements are electrically shortened the notch performance is not great.
Karl NVW
Posts: 163
Joined: Wed Sep 03, 2003 7:13 am

Re: VHF Quantar Duplexer 600KHz?

Post by Karl NVW »

I believe the numbers Escomm is looking at are for the preselector filters. TxRx has a very nice six 10" can BPBR design that is specifically built for 600 KHz T-R separation. Bandwidth of each leg (for alternate operation on two channels) is about 67 kHz with slightly degraded performance: additional 0.8 dB insertion loss and 9 dB less isolation. NOTE: That's for 2 channels, NOT two separate repeater stations simultaneously!!
Karl - WA8NVW AFA5VB
SHARES + NCS
PETNRDX
Posts: 842
Joined: Sun Nov 25, 2001 4:00 pm
What radios do you own?: Too many

Re: VHF Quantar Duplexer 600KHz?

Post by PETNRDX »

Without pulling out the spec sheet on those, my memory says they really were for 2mhz or more.
They are best suited as a filter for a frequency agile base station, hence the 200 khz of bandwidth and the reason for BP rather than BR.
You can use these for "protection" of a remote base at a repeater site and get great sensitivity even near other transmitters. Assuming of course that they TX of the other transmitter and the RX of the base are appropriate. Same with the opposite (RX to the station TX).
I have messed with these extensively and closest "spacing" that I found usable was around 1 mhz.
We are using them around 1.2 mhz with 9/10's dB loss on one side, and 1.5 dB loss on the other. They are not wanting to be reciprocal on the loss when tuned that close. You kinda get what you get.
The loss goes WAY up as you get below 1.2 mhz or so.
Our use is a bi-directional "simplex to simplex" repeater.
Steve K.
Post Reply

Return to “Base Stations, Repeaters, General Infrastructure”