Re: NEW HAM - FT-897 to FT-2900 Simplex Transmit/Receive Range
- I, too, must disagree with the inference that coiled coax causes a noticeable loss in range. If this were the case, coax baluns would have been rejected, years ago.
I operate a VHF communications over a large part of rural Washington state and have never noticed any coverage differences in mobiles with coax either coiled or not. Of course, if your friend's coax was of the foam variety, I would have attributed the improvement to the center conductor migrating to the shield braid, which I have seen.
73, Radio Randy N7CKJ
--- In FT897@yahoogroups.com, Dennis <n8bmb1@...> wrote:
> The coax being coiled does make a difference. I have seen it in person
> and the "wow" factor after it was straightened out. In this case, if
> memory serves, he is on the side of a "mountain" (based on different
> post about different subject).
> But in agreement, there are so many factors in UHf/VHf that it can make
> someone say "why bother?". However, the mobile is pushing 75 watts. He
> SHOULD have heard SOMETHING at 15 miles, even a small S-1 something but
> again, it could be the local noise level killed that too. We just don't
> know. We are working on this off board at this time. I gave him
> several things to check on and am waiting the outcome of that
> investigation before moving on tho something else.
> Dennis - N8BMB
- Hi Donovan;
The answer is: "Yes, you should be able to communicate for a lot more than five miles". Get a SWR meter either off ebay or amazon and check your antennas. The feed line does not need to be resonant if it is 50 ohm coax, but the antennas definitely need to be resonant, that is, SWR of 2:1 or less. If the antennas are cut for 450, and they are both vertically polarized, you should get "line of sight" all day long, which is a bit more than 5 miles even in flat terrain IF (very large "if")your base antenna is off the ground level. Of course, if your base antenna is only a few feet, then 5 miles might be all you can do. See: http://en.wikipedia.org/wiki/Line-of-sight_propagation
I would play around with it (the HAM way!), and see what I got with different installations and configurations.
Note: If your home/base ant. is horizontal and the mobile is vertical (almost certain), then you will have a LOT of attenuation, some say as much as 50dB.
Another note: Use of a SWR meter is very important in both mobile and base operation. Antennas are rarely tuned from the factory due to the fact that the installation can change the SWR radically. A resonant stretch of coax on VHF can cause lots of problems; stay with a random stretch and tune the antenna. Ebay has several workable SWR meters for under $40 US. Make SURE you get the one for VHF/UHF.
There's more, but all that is a start...
No repeaters out there?
73 es GUD DX.
--- In FT897@yahoogroups.com, "Matt" <doormatt@...> wrote:
> Hi Donovan, the answer is that it depends on a number of issues. Firstly, is
> the base antenna mounted outside or sitting inside your house - and what
> height above ground level is it? What is the terrain like over the distance
> that you are trying to communicate over and is your house elevated or in a
> valley? Have you tested the antenna and feedline in both the car and the
> house to see if they are resonant or near resonant for the frequency in use.
> Do you have a long coax run between the radio and the antenna at the house -
> what length is it and what type of cable?
> If in flat terrain and the antennas are in good working order, then I would
> expect way more than 5 miles range. But, lots of variables to look at.
> ----- Original Message -----
> From: "dcawood" <dcawood@...>
> To: <FT897@yahoogroups.com>
> Sent: Monday, April 01, 2013 2:57 AM
> Subject: [FT897] NEW HAM - FT-897 to FT-2900 Simplex Transmit/Receive Range
> > Hello,
> > I just installed a FT-2900 VHF Transceiver in my wife's car. The radio is
> > transmitting at 75watts and is connected to a 19.5 inch mag mount 2m/70cm
> > antenna. I had to go with that antenna because her antenna is already
> > hitting the top of the garage entrance. The base station is a FT-897D
> > connected to a 2m/70cm Ventenna operating at 50watts.
> > Today we did our first drive test. She started from downtown Dallas and I
> > was at home in west Plano.
> > My first contact to her was when she got to northwest highway which is
> > about 15 miles out. With my rx gain at its highest level, I was not able
> > to receive her till she reached Frankford which is about 5 miles out. With
> > the FT-2900 set to 75watt, even on a 19.5" magmount antenna, shouldn't I
> > be able to hear her at least 15 miles out rather then 5 miles out?
> > Regards,
> > Donovan - KF5TSH
> > ------------------------------------
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