What is this? (Radio antenna and strength of signal)

Take a look at this photo. What is that thing on the cab roof that's circled. It's present on older EMUs as well.

Thanks


[/url]

Sinclair VHF radio antenna.

What is the power output on them?

It's amazing I can pick up the MTA police and the Hudson and Harlem line from my home.

SubaruWRX wrote:What is the power output on them?

It's amazing I can pick up the MTA police and the Hudson and Harlem line from my home.

I'm sure that what you're picking up is from a higher powered repeater.

the Power output from radio(not antenna) is 25 or 50 watt on trains

L'mont wrote:

SubaruWRX wrote:What is the power output on them?

It's amazing I can pick up the MTA police and the Hudson and Harlem line from my home.

I'm sure that what you're picking up is from a higher powered repeater.

GCT Station uses a repeater as well? for the last few days I've been able to pick them up with a pretty strong signal.

Actually the Antennas are now made under a new name now. i just ordered one for the valley for number 40. they cost about 260.00 take a few weeks to get custom built/tuned to you frequency they can handle up to 200 watts of power

the actual power out put is set by the transmitter i have not looked at the MNR from what i can see on FCC.gov they are allowed 40watts on the mobile radio but the sinclair has a very gain and output pattern

and GCT uses RPT for other parts of the station but the ROAD is Simpex you can tell on a Clean cap Radio Cause it will 78/78 is simplex

Actually, the Sinclair lists as unity gain. What you'd expect from an omni of that size.

You CAN get omis that are 9 or 10 DB. I just replaced two on a water tower. Each one was 19 feet long - and that's at 450mhz!

Depending on a lot of things, the output at the antenna might be quite a bit less than what came out of the radio. Especially as frequencies climb. I wouldn't be surprised at all if they were down 3 db by the time they hit the antenna, especially if the feedline's thin (as opposed to LMR-400 or such), and the radio's a good distance from the antenna. Plus, don't forget connector losses (which are remarkably significant at high frequencies) and age issues.

I doubt lenght is any problem , the Cable is less than 8 feet long and the biggest size coax that fits in PL-59 connector.

Sounds like a good quality line (LMR-400 or such). The better antenna cables are like that. Really long/high power/high frequency stuff is even more fun - more like plumbing than cable The RG-whatever crap Radio Shack sells has losses that are unbeliveable, especially over 500mhz.

MN's down in the 150ish area, right? Pretty tolerant - when you get up near 500, little things mess it all up I just did the antenna/cable replacement on a water tower (same one with the 19 foot antennas), two 80 foot runs. With an identical new antenna (same make/model, even), and a slightly better feedline (7/8ths inch Heliax vs 1/2 inch), we picked up 10 db.

How old are the repeaters in MN's system? I'd imagine they've been swapped out over the years. But then, I've seen remarkably old (read: vacuum tube) equipment in places - it just managed to survive through the upgrades.

Up around 900 Mhz, errant golf balls hitting feedlines have been known to wipe things out. I once fixed a broken system by just reterminating one end - the entire loss was through a damaged connector.

Metro North works in RR band between 160 and 162 Mhz they do not use repeaters but remote controlled bases, most are big AErotron sets. controlled by RTC's in New york by telephone.

the m2 and the such use a motorola mocom 70 from one of the Doghouses once when they had an open house in Croton awhile back

As for the Rail Road Aerotron They were Design by harris and are actually a damn good radio compared to other Aerotron equipment

plus they also have the MRK portables from GE a very solid radio as well as other GE/Macom the m7 use a Macom Jaguar with a nice display

and there has been a large motorola use increase as well

i got a silly question at the Does the RTC have a Decoder Display with the GE G-star and the motorola MDC-1200 Data Burst for iding

kitn1mcc wrote:Does the RTC have a Decoder Display with the GE G-star and the motorola MDC-1200 Data Burst for iding

No. It's a Penta integrated dispatch system at the RTC desks.

Jim

ahh ok i was wondering cause it seems like all the radios id

All radios on M2s, M4's and M6s are Motorola "MITREK" 4 channel VHF high band units that put out 40 watts of power. M1s, M3s and M7s use and newer Erricsson (sp?) radios.

Most of MN's locomotives use either the Areotron of Motorola "Clean Cab" radios that can access all AAR channels and these units also put out only 40 watts of power. 40 watts is what the FCC allows for railroads.