Converting two VHF high power spectras to repeater.

[cullen3402412]

I am new to this so please bear with me. I am looking to convert two high power VHF spectras into a repeater. Possibly using an Electra 2000 controller. Has anyone else tried this and what are the pros and cons of such. Thanks in advance.

[Jim202]

I am new to this so please bear with me. I am looking to convert two high power VHF spectras into a repeater. Possibly using an Electra 2000 controller. Has anyone else tried this and what are the pros and cons of such. Thanks in advance.

The Spectra receiver is not the best for a repeater. It has no pre filter to reduce close by signals. You would probably do much better finding a Micor receiver. Buying the crystal needed and re tune it for your frequency.

The next item I would suggest would be a duplexer. This would allow you to use one antenna and if you used the band pass type, it would help to reduce any strong signals near your receiver frequency. Use of just a notch type duplexer will do little for near by strong signals.

Jim

[Bill_G]

Did you build a dragster for your first car, or did you buy a used Celica? Most of us bought a used car, and learned how to keep it running before we advanced to something nicer. Same with a repeater. Why not buy a nice used Maxtrac / GR / something-or-other and get grounded in the basics before trying to do something completely different?

[Astro Spectra]

http://batboard.batlabs.com/viewtopic.php?f=10&t=80768

http://batboard.batlabs.com/viewtopic.php?f=4&t=45645

But I'd do a bit more research on the topic of repeaters first perhaps here:
http://www.repeater-builder.com/rbtip/

[cullen3402412]

I appreciate the info. The reason I was. Interested in using the two spectras is that I already have them. I have built a Rick repeater and was hoping to get a little better duty cycle out of a higher power set up. I am trying to gather information from those of you know. Thanks for all the info you can give me on these. I have no problem buying a different receiver. I also have A ge mastr 2 but I wanted the challenge to build my own. If you know of a better direction to go I am open for suggestions.

[Jim202]

I appreciate the info. The reason I was. Interested in using the two spectras is that I already have them. I have built a Rick repeater and was hoping to get a little better duty cycle out of a higher power set up. I am trying to gather information from those of you know. Thanks for all the info you can give me on these. I have no problem buying a different receiver. I also have A ge mastr 2 but I wanted the challenge to build my own. If you know of a better direction to go I am open for suggestions.

The MASTR II would also make a good receiver for you.

Jim

[motorola_otaku]

Duty cycle is all about keeping the transmitter cool. The issue with 110W Spectras is that their heatsinking isn't too robust so even if you blow air on them all day there isn't enough metal-to-air contact to properly dissipate heat. Maratracs are somewhat better, but I'd still advise against running them full-barrel for a repeater transmitter.

If you want a fun project, get one of those cheap 800 MHz MSF5000 PA decks off eBay and drill and tap it to hold a Spectra PA board.

[candrist]

The other thing to consider is that a repeater is only as good as it can hear. Putting out 110 watts is really only good for listening.

My primary repeater only puts out 12 watts to the duplexer. It can be heard for miles and listen for miles. Without a pre-amp I don't need to put out more than 12 watts. More than 12 and I just encourage scanners to listen in.

[com501]

Some of us run 110w mobiles, and some towers have more than 8db of loss from the transmitter to the antenna with combining.

[Jim202]

The other thing to consider is that a repeater is only as good as it can hear. Putting out 110 watts is really only good for listening.

My primary repeater only puts out 12 watts to the duplexer. It can be heard for miles and listen for miles. Without a pre-amp I don't need to put out more than 12 watts. More than 12 and I just encourage scanners to listen in.

I would have to say that over the years, all the repeaters I have seen and had my hands on seem to be balanced for 50 watt mobile operation. Now this will depend on a number of other factors. But if you have a good quiet site, a decent antenna and some elevation, it doesn't take that much power to go a good distance.