Okay, So I will finally stop bugging the board about the stupid controller and the MSF. Now it will be all of the ancillary RF equipment.
Okay Here is what I am running. MSF5000UHF with the internal filtering/duplexer. This is the model with the internal circuit and it doesn't have an "external looking duplexer unit" within the cabinet.
I have been told that the factory MSF filtering and set up is very good (even though it soaks up power output) So I am going to sitck with this set up. (I am in a nasty and congested area)
Here is the external equipment I would like to interface.
1) Angle linear 3 can bandpass filter with recieve pre amp.
2) Celwave dual stage isolator with a dummy load on it.
Here are my questions:
1) Where can I exactly interface this equipment to the MSF
2) How does this isolator get hook up. It has three open ports withh the fourth occupied by a dummy load.
3) Any other suggestions or maybe a diagram on this sorta hook up.
4) Should I buy a harmonic filter, If so where would this go.
**5) Is anyone here able to tune the isolator. It is NOS with the manual.
Thanks, Rob
Filter, Pre-Amps, Isolators and the MSF5000- Info needed
Moderator: Queue Moderator
My two bits worth:
You do not need any of these things!
If you really want to screw up a repeater on a conjested site just put a pre amp on it!
This is a prescription, you need to determine exactly how much gain, if any you need, and pad the amp output for this figure.
It is not possible to hear below the site noise floor.
The noise varies from time to time, so you may get away with rediculous gain such as 18db, however you will have intermittent problems with intermod, desense.
Your sensitivity should be about-117dbm/SINAD.
The factory could have designed the receiver for say -130 however in the real world this is not usable.
In the MSF the cable lengths on the "duplex tee" are critical.
The additional filter would go in the line to the receiver front end, which uses SMA connectors. I have no idea how this would effect your performance, my advice is DONT.
The MSF PA has at least one circulator, possibly 3 depending.
There is no point in installing an extra circulator.
The factory duplex station has a triple circulator.
If you are installing the 5 port circulator, it would go in the OUTPUT line of the PA, which has "N" connectors.
In general, circulators (isolators) must be mounted on an aluminum panel, never steel unless specifically allowed by the manufacturer.
This is due to the strong magnet in the circulator.
Circulators with adjustments are easy to align if you have some basic equipment.
You do not need any of these things!
If you really want to screw up a repeater on a conjested site just put a pre amp on it!
This is a prescription, you need to determine exactly how much gain, if any you need, and pad the amp output for this figure.
It is not possible to hear below the site noise floor.
The noise varies from time to time, so you may get away with rediculous gain such as 18db, however you will have intermittent problems with intermod, desense.
Your sensitivity should be about-117dbm/SINAD.
The factory could have designed the receiver for say -130 however in the real world this is not usable.
In the MSF the cable lengths on the "duplex tee" are critical.
The additional filter would go in the line to the receiver front end, which uses SMA connectors. I have no idea how this would effect your performance, my advice is DONT.
The MSF PA has at least one circulator, possibly 3 depending.
There is no point in installing an extra circulator.
The factory duplex station has a triple circulator.
If you are installing the 5 port circulator, it would go in the OUTPUT line of the PA, which has "N" connectors.
In general, circulators (isolators) must be mounted on an aluminum panel, never steel unless specifically allowed by the manufacturer.
This is due to the strong magnet in the circulator.
Circulators with adjustments are easy to align if you have some basic equipment.
Aloha, Bernie
My $0.04 worth: I have a 110w UHF MSF5000 with the internal duplexer / filter. The power amp has one circulator in it. With 60 watts out of the station's antenna connector, it's actually putting out about 90 watts out of the power amp. The loss in the post-filter is about 2.0 dB. There's a similar amount of loss in the pre-filter, but that doesn't affect the output power too much. These are simple bandpass filters, tuned to the transmitter's output signal. As Bernie said, the TEE cable and the RF Tray's front end filters are a critical and necessary part of the entire duplexer / filter setup. If you install a preamp between the receiver and the TEE cable, you lose all that filtering that the station needs to run duplex with the factory hardware.
You could certainly bypass the two filter sections and hook the power amp output to a good (such as a Celwave 300w bandpass/reject 6-cavity) duplexer, and run a preamp with perhaps 6-9 dB of gain between the duplexer and the receiver. Any more gain will just raise the noise level in the receiver. You should also have a low pass (harmonic) filter on the output of the power amp - the one in my 80w station starts attenuating around 650 MHz to get rid of the 2nd and higher harmonics.
The Celwave base-station duplexers are often for sale on eBay and the prices vary from $200 to $500 depending on condition. A new cable set will cost $250 from Celwave, should you need one. Two of my three units had bad cables. I bought one set new, and made the other set myself for a lot less money.
An external duplexer will have from 1 to 2 dB of loss, depending on how it's tuned and the condition of the cables. You will have this loss on both the receiver and transmitter. It will also notch the receive frequency out of the transmitter signal, and vice versa. With the MSF5000's built-in unit, there is no notching, just bandpass. You only suffer loss on the transmitter, and when it's tuned properly, you will not have any desense on the receiver input with 100 watts coming out the antenna connector (note that this is NOT the recommended power level for a 110 watt station, but I did try it for a few seconds at that setting).
Bob M.
You could certainly bypass the two filter sections and hook the power amp output to a good (such as a Celwave 300w bandpass/reject 6-cavity) duplexer, and run a preamp with perhaps 6-9 dB of gain between the duplexer and the receiver. Any more gain will just raise the noise level in the receiver. You should also have a low pass (harmonic) filter on the output of the power amp - the one in my 80w station starts attenuating around 650 MHz to get rid of the 2nd and higher harmonics.
The Celwave base-station duplexers are often for sale on eBay and the prices vary from $200 to $500 depending on condition. A new cable set will cost $250 from Celwave, should you need one. Two of my three units had bad cables. I bought one set new, and made the other set myself for a lot less money.
An external duplexer will have from 1 to 2 dB of loss, depending on how it's tuned and the condition of the cables. You will have this loss on both the receiver and transmitter. It will also notch the receive frequency out of the transmitter signal, and vice versa. With the MSF5000's built-in unit, there is no notching, just bandpass. You only suffer loss on the transmitter, and when it's tuned properly, you will not have any desense on the receiver input with 100 watts coming out the antenna connector (note that this is NOT the recommended power level for a 110 watt station, but I did try it for a few seconds at that setting).
Bob M.