Having Trouble Monitoring CHP

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mmckenna

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After looking at the antenna i'm not sure if it's a maxrad I don't see any markings on that say maxrad on the crome part or less it came off after years of use. In the inside and it has 27-31 not sure if it's tune for that or it's the model number.
That part number is a Maxrad 34-40Mhz mobile antenna. A good choice for what you are doing. 27-31 might be the coil model, maybe.

Not surprised it won't work well elsewhere. An antenna specifically designed for low band wouldn't necessarily work well elsewhere. There is a lot to be said for having the right antenna for the application. Trying to find a high gain antenna that covers everything is difficult. Sometimes specific antennas tuned for what you are trying to hear work best. An antenna switch can be your friend here.
 

SCPD

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might be the Maxrad MLB2700 27-31mhz will it still be good for low band?
Most antennas come with a cutting chart allowing the antenna to be cut to length to match peak performance at the frequency you desire. The 2700 is designed to be cut for wavelengths between 27 and 31 MHz so the cutting chart that comes with it only covers those 4 MHz. You would be better off purchasing the Maxrad MLB4000 which comes out of the box at a length that provides peak performance for 40 MHz. The cutting chart allows for a length providing peak performance up to 47 MHz.

If I had room for another radio in my vehicle and space on the roof I would install the 4000 cut it to 42 MHz. I would then use this antenna and the radio for low band only. Since the CHP is only using low band for their primary communications with narrowbanding and trunking not being factors an older radio you may have or could buy cheaply could be dedicated for this use. I would also install a newer model scanner, something I already have (PSR-600) allowing me to listen to all the other agencies, but also capable of receiving the CHP 700 MHz handheld frequencies.

I have Larsen scanner antennas mounted on my vehicles that work very well for 136-900 MHz, at least as well as one antenna can given the wide range of wavelength involved. My Forest Service truck had two Larsen WBQ-150 antennas installed on it. One for a Midland VHF High transceiver and the other for a BC-760 scanner.The WBQ-150 is designed for agencies that communicate over the entire VHF High Band, from 136-174 Mhz, using one length. I traveled all over the state to fires and other assignments and found that this antenna performed better on the VHF High, UHF and 800 MHz bands better, as a whole, than any other antenna I've ever used. It is only 18" high so getting in and out of garages and parking structures is never a problem. This is the antenna I initially installed on my personal vehicles. When Larsen came out with their scanner antenna I started using one and found it to perform a little better than the WBQ. It took about 45 seconds per vehicle to make the switch as both antennas use a NMO mount. I highly recommend the Larsen scanner antenna for anyone wanting good performance on the upper land mobile bands. Unfortunately, its performance on VHF Low is not that great, but it is better than other multiband antennas I've used.

Expecting one antenna to cover all bands at peak performance is similar to thinking we can have one animal that gives us milk like a cow; the nimbleness, speed, companionship and intelligence of a horse; and the ability of a mule to carry heavy loads. All of that and the ability to travel quickly and carry heavy loads over snow like a snowmobile. All of this without having a stupid slow cow, a ornery mule and a smelly, cantankerous, noisy and difficult to maintain snowmobile that gets stuck in soft snow before you can say "oh crap."

I don't drive that much as I live in a small town so it isn't worth the effort for me to install a second scanner and antenna just to maximize CHP reception. If I did I would seriously consider having a scanner just for the CHP.
 
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Most antennas come with a cutting chart allowing the antenna to be cut to length to match peak performance at the frequency you desire. The 2700 is designed to be cut for wavelengths between 27 and 31 MHz so the cutting chart that comes with it only covers those 4 MHz. You would be better off purchasing the Maxrad MLB4000 which comes out of the box at a length that provides peak performance for 40 MHz. The cutting chart allows for a length providing peak performance up to 47 MHz.

If I had room for another radio in my vehicle and space on the roof I would install the 4000 cut it to 42 MHz. I would then use this antenna and the radio for low band only. Since the CHP is only using low band for their primary communications with narrowbanding and trunking not being factors an older radio you may have or could buy cheaply could be dedicated for this use. I would also install a newer model scanner, something I already have (PSR-600) allowing me to listen to all the other agencies, but also capable of receiving the CHP 700 MHz handheld frequencies.

I have Larsen scanner antennas mounted on my vehicles that work very well for 136-900 MHz, at least as well as one antenna can given the wide range of wavelength involved. My Forest Service truck had two Larsen WBQ-150 antennas installed on it. One for a Midland VHF High transceiver and the other for a BC-760 scanner.The WBQ-150 is designed for agencies that communicate over the entire VHF High Band, from 136-174 Mhz, using one length. I traveled all over the state to fires and other assignments and found that this antenna performed better on the VHF High, UHF and 800 MHz bands better, as a whole, than any other antenna I've ever used. It is only 18" high so getting in and out of garages and parking structures is never a problem. This is the antenna I initially installed on my personal vehicles. When Larsen came out with their scanner antenna I started using one and found it to perform a little better than the WBQ. It took about 45 seconds per vehicle to make the switch as both antennas use a NMO mount. I highly recommend the Larsen scanner antenna for anyone wanting good performance on the upper land mobile bands. Unfortunately, its performance on VHF Low is not that great, but it is better than other multiband antennas I've used.

I don't drive that much as I live in a small town so it isn't worth the effort for me to install a second scanner and antenna just to maximize CHP reception. If I did I would seriously consider having a scanner just for the CHP.
It has a 49" stainless steel whip, but I see most of the maxrad low band antennas are at 49"
 

SCPD

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It has a 49" stainless steel whip, but I see most of the maxrad low band antennas are at 49"
I assume you mean both the MB4000 and MB2700 have a 49" whip. I think the 4000 is a quarter wave antenna so there is obviously some difference in the coil at the base. If you are indicating a MB3400, a MB3700 and a MB4000 all have 49" whips then the same applies. I think the 2700 is also a quarter wave, which at 30 MHz would require a 2.5 meter straight (no coil) whip. To get quarter wave performance from a 49" whip, approximately 1.3 meters or about 1/8 wave, would require a very different coil.

This is why I expect that getting a 4000 and trimming it to 42 MHz would be best for the CHP. The CHP now covers roughly 39-45 MHz so the mid point is 42 MHz.

Disclaimer: I'm posting this without the benefit of having the Maxrad website and the conversion equation of feet to meters with me. Your actual calculations may vary.
 
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I assume you mean both the MB4000 and MB2700 have a 49" whip. I think the 4000 is a quarter wave antenna so there is obviously some difference in the coil at the base. If you are indicating a MB3400, a MB3700 and a MB4000 all have 49" whips then the same applies. I think the 2700 is also a quarter wave, which at 30 MHz would require a 2.5 meter straight (no coil) whip. To get quarter wave performance from a 49" whip, approximately 1.3 meters or about 1/8 wave, would require a very different coil.

This is why I expect that getting a 4000 and trimming it to 42 MHz would be best for the CHP. The CHP now covers roughly 39-45 MHz so the mid point is 42 MHz.

Disclaimer: I'm posting this without the benefit of having the Maxrad website and the conversion equation of feet to meters with me. Your actual calculations may vary.


Ahh I see! Well I found the maxrad on it it's faded but it's there.
 

W6KRU

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I just tried another antenna I had laying around. It is a Larsen NMO 150 5/8 wave. It works darn well on vhf-low. I am hearing CHP offices that are way out there like Newhall and Arrowhead. It also works really well on vhf-high as it should. I am guessing it will be weak on milair and 450 freqs.. but I'm happy with vhf-low and vhf-high.
 

RolnCode3

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Not an engineer, but: I think unless you're going to transmit, it's not that crucial your antenna be perfectly cut. I bought a Larsen low band and didn't cut it. I've also found a CB antenna on the side of the road. Remove the loading coil and the whip worked great. Get something reasonably close (aka really long) and it'll probably be a huge improvement over whatever you were using before.
 

mmckenna

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Correct, for receiving, you don't need to have a tuned resonating element, but it does help a bit. Getting something close would work just fine.

1/4 wave at 42MHz would be about 66 inches. Anything close to that would work. Shortened with a loading coil would work too. It's easy to make a 1/4 wave antenna for home. 66 inch tall element with a couple of 66 inch long ground radials underneath. Easy to do and directions all over the net.
 

RobVallejo

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I have no trouble using the scanner and programming. In fact, I can monitor my local sheriff/fire etc. without any trouble. Trying to monitor CHP is not working for me and I cannot figure out what is wrong.

Here's the frequencies I have programmed:

Ukiah base 42.56
Ukiah mobile 42.72

Santa Rosa base 42.80
Santa Rosa mobile 42.20

Napa base 42.42
Napa mobile 42.66
Since you are having trouble only with the low band, you might be able to hear some of the traffic on the high-band lima frequencies: Department of the Highway Patrol (CHP) Scanner Frequencies and Radio Frequency Reference

From where I am, I can hear one of the base frequencies rebroadcast on 453.825. I think it is the Amber, but I haven't paid much attention. Maybe you can hear Napa or Santa Rosa on one of the other Lima's, at least until you get your antenna up and running.

Good Luck.
 
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Got the antenna up but not where I want it i'm having problems with the bracket going to get a new one on Monday . One thing I notice on the green the Hollister-Gilroy /Santa Cruz sounds like the Hollister-Gilroy units are still on the old green I can't pick up green 2 i'm guessing the Santa Cruz units are on it.

EDIT: I Just looked up the FCC listing on the green2 looks like only one site the Ben Lomond site has only switch over that explains why I can't pick it up it's to far
 
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Benoxpd

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CHP ventura county

Hello I have a bct320a scanner and a bct15x scanner. I live in the ventura county area and i have a CHP office near me not very far. I used a magnet antenna on my car and it works to get the CHP radio but it's not clear it tends to go away. So I had an nmo antenna drilled on to my trunk for my p71. That antenna is a 2 meter 34 inch. But it doesn't work with that one at All. My magnet antenna is way smaller it's cobra magnet antenna I think. So I want to buy a antenna that would get that same signal 42.400,45.4000 does any one know what type of nmo antenna can I use to put on the roof of my car??????
 

ochbchuck

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Hello ArtP I live in the So Cal. I use a mobile mount DVB-T Antenna to monitor CHP. I have it in the trunk of my car, not even mounted to the outside. Big improvement from the stock whip antenna. Also pickups 400 and 800 Mhz as well. You can find them on Ebay for a few dollars. I even have a second one sitting on my desk. What I also found that as soon as I start my car the reception for the CHP decrease with the scanner in the front seat and a whip antenna. I am not a RF engineer but something with the engine running hurts the low band range. And this happens with three different cars that I tried. It took me a few tries with several different antennas. I was using a whip that was 14 inches long. It work ok but got in the way a lot. Good Luck.
 

RadioGuy1951

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ArtP...if I lived in (the town of ) Clearlake I'd try these (I used to live in southern (f)Lake Co):


Northern Div - Ukiah Dispatch Blue2 - 44.980 B 42.220 m - UHF1 - 460.450
Ukiah -18 - Ukiah - White 42.560 base 42,720 mobile
Clearlake - 7 - Kelseyville - White 42.560 base 42,720 mobile
***********************************************************************
Golden Gate Div - Vallejo comm center Blue 42.340 B 42.180 M Blue 2 44.720 B 42.300
Napa 21 Grape 42.420 B 42.660 M
Santa Rosa 17 Emerald 44.800 B 42.480 B
**********************************************************************
Valley Div - Chico Dispatch - Blue 44.840 B 42.360 M
Williams 39 Brown 44.700 B 42.260 M

There are repeaters for the CHP on both Mt Konocti & Mt St Helena. I use a simple radio Shack magmount antenna with an adaptor for my scanner. If you want to go portable I suggest an extendable metal whip antenna (I have one with a swivel). Is your scanner an older one without much sensitivity..? How tight do you set the squelch..?

There are also UHF frequencies that are used for point to point links between Mt Konocti & Mt St Helena (and Santa Rosa & Vallejo)
 

jnvc57

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CHP Freqs Valley Division

I am having trouble hearing anything these days on CHP Green Valley Division Placer County area. Anyone have an idea? I know their hand held portables have been switched to a 700 Mhz frequency not sure what it is. I have heard in the past they might try to move that way with mobiles. I think it might cost prohibitive.
 

oracavon

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I am having trouble hearing anything these days on CHP Green Valley Division Placer County area. Anyone have an idea? I know their hand held portables have been switched to a 700 Mhz frequency not sure what it is. I have heard in the past they might try to move that way with mobiles. I think it might cost prohibitive.
Could you possibly mean Grass Valley? Green Valley is between Napa and Fairfield, northeast of SF Bay. Grass Valley is in Napa County, which is next to Placer County.

Assuming you really mean Grass Valley, it's part of the Sacramento Dispatch Center. You can find the frequencies on the RR CHP webpage here: California Highway Patrol (CHP) Scanner Frequencies and Radio Frequency Reference

The new extender frequencies for that area are 769.46875 and 769.19375.

The 700 frequencies are planned only for the extenders. CHP intends to stay on VHF Low Band for base and mobile operations because it provides the best coverage over large areas of varying terrain. Switching to UHF frequencies would require many more towers to avoid creating the numerous dead spots that would result from the radio propagation characteristics of UHF.
 
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