Antenna for picking up Worcester P25.

[shustakc]

I want to listen to Worcester Public safety. Have a BCD996XT, and live on a hill in Holden.

The reception of said signals is weak with a BNC telescoping antenna in the back of the radio. I barely see any indication of a signal on the meter, and reception is occasionally broken.

Friends tell me that they pick up Worcester from Boston, and the signal is strong. I'm trying to figure out if it's my radio, my location.

Any ideas on how I can go about figuring this out? I figured the best way would be to have someone bring their radio here to see if it's better than mine. So far, asking on my local ham radio repeater has been a wash.

Thanks

[ScanBoston]

Christine, So you have these four possible control channels in the scanner. 858.1375, 857.2625, 856.8375 and 856.5125. The scanner is set to Motorola P25 Trunking. Talkgroups for Worcester PD are 4369 East Dispatch and 4371 West Dispatch. As I said I get the system solid after Framingham on the Mass Pike on a portable inside my car. Marlboro as well and driving through Holden and Paxton. Dave K1PRE, can get them in Littleton MA but he is using an outside antenna. I do not get them in the Boston Area. The Best Antenna for just them would be an 800 MHz Beam aimed wherever you get the strongest signal. A discone would also work okay if you still want your area VHF and UHF at the same time. I can bring my portable your way someday for a test just not sure when. https://www.snewiki.com/wiki/index.php/ ... r_Regional

https://www.ebay.com/itm/222872308941?e ... R5bBlNOdYQ

https://www.ebay.com/itm/222871928685?e ... R8qcotOdYQ

[MrSvenSven]

Another possibility is that you are suffering from simulcast distortion, which you can read about here:
https://wiki.radioreference.com/index.p ... Distortion

If that's the case, your problem might actually be receiving the signal from two different radio sites at once (Worcester has 5). The solution to that would actually be a smaller antenna. The only real way to know is to experiment. Try different antennas, both large and small. Try different locations in the house.

[shustakc]

First, a couple of questions.

I'm interested in monitoring fire, west side police and east side police.

Is any of this phase 2, or should my phase 1 scanner work fine?

With my 996XT, I barely get one bar of S meter signal strength. Mostly no bars. Which seems strange as I live on a hill in Holden near the Worcester side of town.

I was going to visit a ham friend, bringing my scanner to his place. He has a Home Patrol. I wanted to compare his reception on his radio to my radio in the same locale. For whatever reason, he's not hearing anything either. We are hearing stuff on broadcastify (although they don't specify if they are monitoring east or west side traffic.)

[ScanBoston]

Try this one https://openmhz.com/system/worcester
Use the filter at the top to customize what you want.

PD and Fire are P1
Shewsbury all P2
Some Worcester City Services are P2 but if any older radios are involved the talkgroup shifts to P1.

[shustakc]

Thanks John.

I'll keep you updated on what I find.

[nikronzo]

Christine, when I get back in town this weekend I can give you a hand on getting Site 36 working for you, There is no issues with the trunk from the south side of Holden, usually I get an RSSI of about -108 on my portable in my basement, the Control channel is always 858.1375 and only changes when a site needs maintenance done. The nearest tower to us and the strongest signal is from the Millstone greenhill park tower but the Worcester trunk is P25 simulcast CQPSK so the airport tower can cause simulcast distortion as John mentioned.
-Nick

[nikronzo]

also in terms of talkgroup status, WPD F1 and F2 are strapped FDMA phase 1 along with city fire admin, dispatch and firegrounds and EMS Dispatch. All other PD talkgroups for instance are strapped for RC4 encrypted TDMA mode

[shustakc]

Christine, when I get back in town this weekend I can give you a hand on getting Site 36 working for you, There is no issues with the trunk from the south side of Holden, usually I get an RSSI of about -108 on my portable in my basement, the Control channel is always 858.1375 and only changes when a site needs maintenance done. The nearest tower to us and the strongest signal is from the Millstone greenhill park tower but the Worcester trunk is P25 simulcast CQPSK so the airport tower can cause simulcast distortion as John mentioned.
-Nick

Thanks.

Something is wrong as I'm getting nothing now.

Talk to you later.

Chris

And thanks.

[shustakc]

Brought home a used 536 last night, and after some serious reading in the manual, and watching some Youtube videos, I got Worcester programmed into the radio. The control channel is very weak on that one as well.

This surprises me as I am probably almost line of sight to Airline Drive (which is where I think one transmit site is), or the airport. Maybe it's because it's 800 mhz, and my house is sided with aluminum. Radio reference claims there is a site at Asnebumskit, but I don't think that's correct.

I don't think distortion is an issue because the transmissions are barely giving me 1 bar if I am lucky.

[W1KNE]

Radio Reference parses the site data from the license.

https://wireless2.fcc.gov/UlsApp/UlsSea ... ey=1302616

Here are the licensed sites. Note, mobile sites are deleted.

Call Sign WPAR399 Radio Service YE - PubSafty/SpecEmer/PubSaftyNtlPlan,806-817/851-862MHz,Trunked
9 Total Locations
10 Locations per Summary Page

Locations Displayed:
All | Fixed | Mobile | Itinerant | Temp Fixed | 6.1m
2 - Fixed MOUNT ASNEBUMSKIT RD PAXTON, MA WORCESTER County 42-18-14.3 N, 071-53-49.3 W
3 - Fixed BELMONT & SKYLINE DR WORCESTER, MA WORCESTER County 42-16-36.3 N, 071-46-48.3 W
5 - Fixed BEHIND 442 SOUTHWEST CUTOFF WORCESTER, MA WORCESTER County 42-13-19.0 N, 071-46-26.0 W
6 - Fixed 375 AIRPORT DRIVE WORCESTER, MA WORCESTER County 42-16-11.0 N, 071-52-16.0 W
8 - Fixed Special Condition MASONIC HILL SHREWSBURY, MA WORCESTER County 42-18-25.6 N, 071-42-48.7 W
9 - Fixed Special Condition 20 CENTECH BLVD SHREWSBURY, MA WORCESTER County 42-15-34.0 N, 071-41-40.0 W

Are you getting a weak control channel in hold mode or in trunk tracking mode?
There is a difference. If you have a low signal in TT mode, it could mean you're getting hammered by LSM.

Try entering the control channel only in "hold mode" and see how strong it is there.

You could also be getting "desensed" from another nearby cell tower if you have one. Especially if it has T Mobile 600 MHz users on it.

[shustakc]

Didn't they shut down Asnebumskit? I literally have line of sight to the tower there, so I can't imagine that the site is active. I would be getting the meter pegged.

[jbella]

Asnebumskit/Paxton is shut down. That elminated my hearing Worcester at all to the north. But you being in Holden should be able to get that system with no antenna.

Something isn't right, as others said, possibly interference.

[shustakc]

$%%#^@%$$!!

I just erected a Tram Discone antenna about 20 feet above the ground. Fed it with 20 feet of RG58. DId a scan with my antenna analyzer, and the SWR from 50 mhz to 600 mhz is less than 2:1. Have no idea what it is at 800 as my analyzer doesn't go that high. It is not yet grounded, aside from the electrical conduit mast sitting on a wet board on the ground.

I'm on a 1000 foot hill, so not in a valley.

Attached the antenna to the scanner, and it's no better than the back of the set whip inside of an aluminum sided house.

Barely 1 bar. Mostly no bars.

WTF?

Looking at a topo map, I'm at the same elevation as the Airline Drive site in Worcester, with no hills in between the locations.

This seems very strange to me. I have not worked in the 850 mhz world before. Only 144, 220 and 440. But I would expect at least slightly better meter readings with the outside antenna.

Chris

[W1KNE]

I really think you're having simulcast distortion, especially at that height.

Try the lowest gain antenna you can find, even a small back of set antenna.

Or a receiver designed for simulcast.

[shustakc]

Would distortion reduce the signal strength as seen on the S meter? Why am I seeing practically no signal on the LCD display?

[W1KNE]

Would distortion reduce the signal strength as seen on the S meter? Why am I seeing practically no signal on the LCD display?

If you're going by the signal meter while in trunking mode, absolutely.

Usually interference will be picked up by the detector in the scanner and falsely read a strong signal.

[shustakc]

"If you're going by the signal meter while in trunking mode, absolutely. Usually interference will be picked up by the detector in the scanner and falsely read a strong signal."


I understand the distortion issue from the radio picking up signals from multiple transmission towers at the same time. Your explanation about this was excellent. I am still confused though. Your comment seems to be saying opposite things. I

With the outside antenna, I'm not seeing a strong signal. Seeing no bars, and maybe occasionally one. Exactly the same result as using the back of the set antenna inside an aluminum sided house. I'm seeing this on both scanners, so I don't think it's a radio thing. Again, using a back of the set whip, doesn't change the S meter reading. This seems intuitively wrong. I expected to see at least one or two bars of improvement from getting the antenna outside of the aluminum siding, and up 20 feet.

Is 20 feet of RG58 instilling huge losses, erasing any benefit from the outside antenna? I figured 20 feet would not inject enough loss to be an issue.

If I install a homebrew, 10 element quagi, would that help? More gain, and the ability to point at one tower, while cutting the signal from any of the others.

I do see one improvement with the outside antenna.

Despite the lack of S meter bars, I'm getting better copy on the WPD and WFD signals. No breakup, so audio distortion, no drops.

At least last night, the copy was much better. I'm concerned that when the trees leaf out, the signal will not be copyable.

[shustakc]

Here's what I did and found.

Uniden BCD536hp, Tram Discone antenna on top of a 25 foot mast. 1000 feet above sea level.

1. Upgraded the 30 feet of RG58 to 50 feet of LMR400. Added one bar of S unit reading from 1-2 to 1-3 peaking. I expected a lot more. Did 50 because I intend to add another 15 feet to the height.
2. Water in the Tram antenna wiped out reception. Using a VOM, normally there was an infinite reading between center pin and ground. With the water, 1 meg. Took the center hub apart, dried out the antenna, and caulked up the antenna. Fixed.

800 meg is a lot different than even 440. I'm maybe 8 miles from the transmit tower for Worcester, but reception is tough. Next thing I'm going to try is a homebrew yagi for 800 to see if that helps.

NO problem with distortion. Now getting clear reception with no drop outs.

[ecps92]

it may have already been stressed, but keep in mind, sometimes TOO Much antenna can be the issue
Some folks have had luck with the 'distortion" of simulcasting by using a paperclip

Here's what I did and found.

Uniden BCD536hp, Tram Discone antenna on top of a 25 foot mast. 1000 feet above sea level.

1. Upgraded the 30 feet of RG58 to 50 feet of LMR400. Added one bar of S unit reading from 1-2 to 1-3 peaking. I expected a lot more. Did 50 because I intend to add another 15 feet to the height.
2. Water in the Tram antenna wiped out reception. Using a VOM, normally there was an infinite reading between center pin and ground. With the water, 1 meg. Took the center hub apart, dried out the antenna, and caulked up the antenna. Fixed.

800 meg is a lot different than even 440. I'm maybe 8 miles from the transmit tower for Worcester, but reception is tough. Next thing I'm going to try is a homebrew yagi for 800 to see if that helps.

NO problem with distortion. Now getting clear reception with no drop outs.

[garys]

Where was the water getting into the antenna? I have a Tram 1410 and if I have to take it down and seal it, I'd like to have an idea of what to look for.

Thanks.

Here's what I did and found.

Uniden BCD536hp, Tram Discone antenna on top of a 25 foot mast. 1000 feet above sea level.

1. Upgraded the 30 feet of RG58 to 50 feet of LMR400. Added one bar of S unit reading from 1-2 to 1-3 peaking. I expected a lot more. Did 50 because I intend to add another 15 feet to the height.
2. Water in the Tram antenna wiped out reception. Using a VOM, normally there was an infinite reading between center pin and ground. With the water, 1 meg. Took the center hub apart, dried out the antenna, and caulked up the antenna. Fixed.

800 meg is a lot different than even 440. I'm maybe 8 miles from the transmit tower for Worcester, but reception is tough. Next thing I'm going to try is a homebrew yagi for 800 to see if that helps.

NO problem with distortion. Now getting clear reception with no drop outs.

[shustakc]

I sealed three locations.

You have the horizontal circle of radials that is the radiator. Those elements bolt to a 1 inch diameter hub. A hex head bolt holds that hub onto the ground plane cone, and attaches the radiator to the center pin of the S0239. The S0239 is attached to a hub that also connects to the elements that make up the cone - ground plane. A black plastic cylinder insulates the radiator from the ground plane.

I removed the bolt, and disconnected the radiator from the cone hub. I then removed the black, plastic insulating cylinder.

I put a moderate coat of silicone on the surface of that black, plastic cylinder that fits inside of the ground plane hub. I also put a coat on the top surface of the insulating cylinder that mates with the radiating hub above it. Finally, once I bolted it back together, I covered the hex bolt head with silicone.

If that is still unclear, I can shoot some pictures.