Thanks folks...
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no one is really answering the question so i will, the vertex is 5-600 and a pyramid will run u about a grand when is all said and done.kc2kuy wrote:Well i need to know whats a good price for one and where can i find one already to go..Again i am looking for the 151-158 range..Thanks...
firegood wrote:We run pyramids on our engines for when the repeater is out, they work awsome.
On a seprate note, something i have never understood. If you are running a in band repeater off two antennas with a frequency difference of 10 or 15 mhz why cant this be done with a set of mobiles, Without all the special filtering that pyramid sells.
That's an awefully baseless statement. Just because you may not need 110w mobiles, does not mean others around the county do not. Our state-wide VHF system is built around 110w mobiles and 5/8w antennas, and even then it's a haul in some places.afterimage84 wrote:you absolutley can...unless you are pushing out 110 watts...which no one should be in this day and age, yet it still happens...
you don't NEED the filters and such....
I'm with you guys.afterimage84 wrote:Worse...not at all.
It is NOT a baseless statement. It is a true statement. There is no reason anyone should be running that kind of power (here is the key to the statement) in this day and age...
You are saying you have a state wide system and it a "haul" in some places even with 110 watts? Well thats a system that needs an overhaul. Just out of curosity, have you ever TRIED a lower power radio? I am certian it is an area of the blockheaded "but we have ALWAYS had 110 watts!"
But yes, with that kind of power you definately need the filtering....and some hot dogs to cook on the antenna when you talk.
AEC wrote:Most certainly CAN be accomplished with even low power radios, I've built several ham repeaters for folks using the garbage Hamtronics boards with TCXOs and dual whips for TX/RX with a single BpBr can to notch the IMD products and I can take a 2 watt HT over a mile away from the car and still hear my output on another HT held in my hand.
All things considered, even a 10 watt mobile repeater is easy to design for vehicular use IF the proper precautions are dealt with.
No fancy duplexers needed, just a single can is all you should require, along with a moderate gain GaAs FET preamp AFTER the filter on the RX side feeding the receiver.
Good grounding and shielding is a must in any environment, and the vehicle is no different.
The cabinet this was built inside of had partitions for all modules, including feedthroughs for DC, audio, RF and control signals if using even a cheap controller, or just an audio level switch to engage the transmitter.
I use a power mosfet for switching the TX and mic audio lines and this setup works like a charm and has yet to suffer from any sort of heat related issues or RF induced problems.
Every DC line and audio level line was filtered and used double shielded cabling with ground points along the lines to prevent RF ingress and keep the audio signals free of spurs.
Old Motorola MSY repeaters had a handy 3-cavity filter in the 12 watt (on UHF machines) transmitter section that tunes easily in the 150 Mhz range and is a snap to get resonant on the frequency of choice to use as a filter on the rceiver input, ahead of the pre-amp.
You can also locate a low power circulator and place it on the transmitter to prevent IMD products of desensing your input while keeping stray RF off the air.
Remember to terminate the circulator with a load that is at least twice the level of RF you intend to run, and make certain it is rated for continuous duty, and not intermittent, in case the transmitter remains keyed due to some form of failure, and if possible, bolt the load to the housing for added heatsinking.
That's all I have for now...
Good luck in your endeavor!
P.S. You should be able to construct this easily using readily available radios and components for well under $600.00 and have a kick butt system.
Remember the K.I.S.S analogy...it does work.
Some things are better when kept to minimal requirements that meet the goals you have.