we have a Marti RPT-15 with a really old not so sensitive receiver and an Energy-Onix Roadcaster with a quite sensitive receiver. Receive antenna is at our FM site, at about 320ft and comes down on 7/8 heliax. it is an old vhf 2way antenna that was abandoned years ago and has worked quite well. I'm just trying to figure out before I make the trip over there to test this if it has a chance at working. Tx antenna would be a 7.2dbi yagi on a tripod on top of the pressbox. I can use either the Marti or roadcaster tx, roadcaster being the higher power unit at 40w. the only test I have done so far is from about 10 miles with a small whip antenna and I still had a full signal on the rx at 10W.
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Marti/Roadcaster range
- Thread starter stephend2
- Start date
Interference and obstructions are usually a worse problem than range. 10 Watts increased to 40 Watts is 6 dB, might make the difference in noise and quiet on a longer shot. We used to use stacked steerable yagis, and got fairly good results. The only way to tell if a given location will work, though, is to take the radio there, turn it on, and have the programming folks listen and decide if it's useable or not.
stephend2 said:
I once had the advantage of having a similar setup with a receive antenna up high on a broadcast tower. But the difference was our receive antenna was directional, and on a rotor.
Being up high with an omni receive antenna is not an advantage when it receives interfering co-channel signals that it would not 'hear' if it were lower. In congested areas of the country this is a serious problem.
A yagi transmitting antenna is a great way to increase the transmitted signal if you don't have brute force watts. But it must be aimed carefully; the more directional it is the more critical the aiming is. Depending on the antenna support design, this may or may not be easy in a remote environment. It is much simpler if the transmit antenna can be omni. If it is vehicle-mounted, you can drive up and start transmitting.
With a directional receive antenna, however, you are able to either maximize the received signal OR minimize any interfering signal. You are actually increasing the valid signal while simultaneously reducing the amount of crap the receiver has to deal with. While it too must be aimed carefully, a rotor location can be stored for repeated use, such as remotes at the same place every weekend, for example. The station I worked at had a signal strength meter from the receiver remoted into the control room, where the announcer could set the rotor for maximum-quality signal visually and aurally.
Everyone has their own way of doing things. This worked really well for us.
Kind Regards,
David
We've got an omni on a 7200' mountain top, nearly 4000' above the metro. Main problem is all the RF up there with 99% of the TV's & FM's within 800 feet and the Marti receivers propensity to mix signals in it's IF. In the Marti's those little coax’s with the RCA connectors between modules make great antennas even with the cover on. Cavities & isolators on everything.
The good part is the nearest other market is 200 miles away.
We’re trying a Moseley RPL4000 receiver up there next week. Have really good luck using one with some close high power 454 MHz paging transmitters at another site.
The good part is the nearest other market is 200 miles away.
We’re trying a Moseley RPL4000 receiver up there next week. Have really good luck using one with some close high power 454 MHz paging transmitters at another site.
Please pardon me if I point out something obvious. Dont forget polarity when planning your systems. We had a pair of stacked yagis on a 20' tower on top of the highest hill in the city. We marked the rotor with directions to the various high schools so we could preset them and listen for the guys setting up for games, ect and then fine aim for quieting. Mostly didnt need to. But I always had to remind them to orient their transmitting antenna horizontally since that is how I set up the recieving yagis to minimize interferance from other 450 mhz tx sources such as paging and land mobile which are typically vertically polarized.
well I see a couple people are on 450MHz. I'm using 161.76. receive antenna is vertical so I'm going to mount the tx antenna vertical as well and stick it on a tripod we can throw up on the roof of the press box. I'll be driving over this weekend or early next week to test it out. Interference is not much of a problem, freq is clear at the rx location, the closest thing to it is our fm signal, for which I have a tuning cavity on the rpu receiver to take care of anything off frequency. We're running 1.95KW at 105.5 and the only other thing on the tower is a 1KW paging system on 929.
according to google earth, the game we're doing on the 9th is 38.5 miles. the receive antenna is 4.5db gain, omni on about 350ft of 7/8. I've got a cavity on it to filter out 105.5 as the antenna is sitting about 10ft above our fm antenna, erp is 1.95kw. I've got a 7.1db yagi on a tripod to take out in the field, should be able to get it on the roof of the press box, using an energy onix roadcaster @ 40w
We have good terrain ham handi talki range from that distance on vhf with those circumstances. 2 watt w rubber duck antenna. Really want to help it. Add a Gallium Arsenide Prepamp.
I ended up having a bad antenna that would not tune so I never got around to trying it out from that distance, maybe next year we will try it out. We're pushing the schools now to provide internet access at the ball fields, we already have it at a few places and it works great with a barix instreamer 100 and an exstreamer 100 at the studio.
That'll give you time to re-cap the Marti equipment before next season.
Over the last few months (getting the repeaters ready for winter) every time a Marti's pulled out to fix it we end up shot-gunning all the caps to make them work.
Over the last few months (getting the repeaters ready for winter) every time a Marti's pulled out to fix it we end up shot-gunning all the caps to make them work.
what software are you using to get the audio back? currently I have a barix instreamer 100 connected through a router with a verizon card that has caused plenty of trouble and dropouts
we got the local schools to put in an ethernet jack at their ball fields so we use their internet connection to send audio back and that works great.
we got the local schools to put in an ethernet jack at their ball fields so we use their internet connection to send audio back and that works great.
Just FYI guys... if you ever need Marti manuals, I have them all on CD here. I was Sales Manger at Marti until 2005 at which time I moved back to Texas. So..give me a call and I'll email one to you.
John Lackness
SCMS, Inc./Southwest
Schertz, Tx
877-390-7267
John Lackness
SCMS, Inc./Southwest
Schertz, Tx
877-390-7267
Anyone know what's in those "frequency Control Modules"?
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