BC245 & Balto Co

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bwhite

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I have a BC245, occassionally use it in my vehicle on I-83 north and south (at rush hours). Seems like I can go many miles (like yesterday during the ice/snow event) without hearing anything on Balt Co Fire (whole county) or the PD. I can't believe I'd go for 15 minutes and hear nothing. A few times I pulled over and ran it thru the Weather service band and some conventional and then put it back in trunk mode and it seemed to finally wake-up and pull in Balto Co trunked stuff.

Batteries are good and attenuation is not on.
Once it woke up it seemed fine.
The kicker is that "Scan ID" rolls accross the screen the whole time.
Even when I kick it over to SEARCH mode it doesn't seem to yack too much.
I don't see anything locked out; is there some sort of "tone" system that I may have inadvertently turned on that is not passing the transmissions?
I have seen it get a bit lethargic when the temps get below 20 degrees but this
isn't the case on the days I'm mentioning.
 

ka3jjz

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Dumb question - do you have ALL of the frequencies programmed? A very long time ago, there was a post about 1 frequency having some problems and folks having to drop it in order to scan correctly. I don't go that way - in fact, I work in the Woodlawn area, and also use a 245, but I can't recall ever seeing this kind of problem. The first thing I thought of was desense (given the area) but I don't think that's the issue here. 73s Mike

[edit] Since the 245 isn't capable of detecting tones, that's not it either. But it CAN detect the trunk disconnect tone - and there is a way to defeat it that is NOT in the standard manual. While trunking, hit the SVC key. The DATA symbol should appear with a line thru it, flash 5 times then stay on. This indicates that the 245 will not respond to the tone if received. To restore it back the way it was, simply hit the SVC key again. This was on the 245 list from a LONG time ago.
Thinking about this a little more, it almost seems that something is preventing the 245 from connecting to a tg during scan - taking it out of scan, then back in would force it to reacquire the control channel and recalculate the first talkgroups. Maybe, just maybe, something is fooling it into activating the disconnect tone?
 
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ka3jjz

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Thinking about this a little more (and now with a clear brain after a good nite's sleep....) there is a time when what you describe happens to me. When I try to use my 245 to listen to the ARINC system at BWI. The system is very low power, and the control channel can get really noisy. What happens is that the freq for the control channel will flash momentarily, then go back into ID Search. It will appear to be dead silent, just like your incident.
I would flip back into manual mode (if possible) and see if you're hearing the control channel without any noise or crud. If not, you might be having the same issue I do; when the CC gets noisy or ratty in any way, the 245 appears to 'go to sleep'. Sometimes if I stopped and restarted trunk scanning (just like you did), it'll work for a bit, but then the problem with the CC reoccurs.
This is much more likely to be the issue you are having.
Before I forget, I would recommend not leaving the 245 in your vehicle. Theft problems aside, this is an old scanner, and components - particularly the display - aren't going to be real happy about extremes in temperature 73s Mike
 
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bwhite

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Know what you mean about the temps on the 245.
I'll give it a non-trunked listen next time, should be plenty hard on the ears.
In the meantime I'm gonna try to borrow a mag-mount CB antenna and convert the plug over for BNC. I think that will help, has on my regular car with another non-trunked scanner.
Yes, the stuff come in 10x better than with the rubber-duckie in the car.
PS--good memory, the freq problem you referred to was instigated by me.
 

ka3jjz

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A CB antenna is going to be horribly inefficient at 800. See if you can borrow someone's cell phone mag mount antenna and slap a proper connector on it. It will work much better, I'm sure. This would simply be to test on 800, as such an antenna is also going to be horrible on VHF hi and lower (you MIGHT get away with it on UHF...)
A duckie inside a car??? Even giving the fact that the duckie on 800 will work - somewhat - a better solution is going to be an antenna on the car. No doubt of that.
73s and GL...Mike
 

bwhite

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Yeah, I just kneeeeew you or someone else would react like that, ha! ha!
Fear not, it ain't permanent, I'd much rather put an 18" 800 mhz (is that still their approx height? haven't looked in years) up there than a 3 or 4 foot tree-branch-catcher.
Hey, if it's better with the "horrible" antenna just think what the right antenna will do.
Not sure what you meant in your last duckie line.
 

ka3jjz

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A duckie is the piece of you-know-what type of antenna that comes with a handheld. A rubber duck is a more proper name; a duckie is deliberately derisive, because it's very much a compromise on most all the ranges it's supposed to cover. Where the name actually came from...that I don't know.
A 800 mhz 1/4 wave antenna is only an inch or two high. The antennas you see on county cars are likely a gain antenna of some type, but still quite short. A cellphone antenna is generally speaking broadbanded enough to work just fine for 800 mhz systems like the county. 73s Mike
 

bwhite

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Yeah, pretty much know the story with the rubber duckies.
Regardless of their shortcomings (a compromise of everything), they are an improvement over their predessors --- the dipole antennas we all had on our radios and such years ago that nearly always broke off.
 

bwhite

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Well, a bit of follow-up,
Ran with the 245 in the same areas of the previously reported "no reception" on the duckie and did hear transmissions via the CB antenna. Some clear some crackling, seems like that area should be well covered with signal since it surrounds Towson, the county seat. Anyway, KA3JJZ, are you using one of the discussed 800 mhz antennas on your vehicle, if so, are you pleased with the investment?
Thanx
 

ka3jjz

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Now we know why you've been having so much trouble! That area is one we hams have called RF Hxxx for a long time. I've done several July 4th parades there (working for the local ham club), and it's a nightmare. Between all the business band, paging, multiple towers and multipathing, (not to mention desense from getting hit with all that RF all at once), there are sections of Towson I wonder if I will hear ANYTHING useful. It's a VERY bad area for scanners and Hams alike, RF wise.
I use an Austin Spectra on my car with a heavy duty Diamond NMO mount. While I wish the antenna did a better job on commercial air, it does just fine on 800. It's a low gain antenna, and seeing that I'm often in urban areas, I don't want anything that gives me a lot of gain there. In this case, less really is more. I get hit with pager intermod in Woodlawn a bit more these days since a couple of new transmitters have evidently gone on the air recently (going to have to get a PAR filter for that), but that's not the fault of the antenna, it's the 245 getting clobbered.
73s Mike
 

bwhite

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Now I'm real curious what to do.
By the way, I'm not truly in Towson, just the I-83 Harrisburg Expressway, a little bit of 695 and then the northern part of the JFX, but, chances are these are all well within RF H###.
Anyway, most of my existence is up here where Carroll, Balto, and York counties come together in the Lineboro/Manchester/Hampstead zones; up here, if I understand it correctly, I need an antenna with decent gain; correct ? If so, should I find one with decent gain and then just attenuate the radio when I'm in RF ### ?
Thanx for your many words of wisdom and experience.
 

ka3jjz

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Generally speaking, I would split the difference a little bit; you might want some gain on some bands, but not on others. I would not want too much gain on 800, perhaps a bit more on VHF hi and maybe - just maybe - VHF lo band. I'm not too familiar with that area you mention, but at least part of the Expressway is on the very edges of the hxxx area. Remember - older scanner, and no matter how bulletproof you think the front end is, chances are that when you're in an urban area, a gain antenna is going to give you grief. That grief could show up as pagers blaring, radio going dead, choppy reception on certain bands...there are too many symptoms to be sure.
Let's see, Carroll and Baltimore counties both have 800 systems, but York? The last I had heard, they still mostly used VHF hi (I haven't lived in Pa. in almost 20 years now, so don't take that as gospel), tho their fire stuff is still low band. I would think you'd want some lo band coverage, if for nothing else, to get the 47.32 and 47.40 SHA stuff (particularly important when the white stuff starts coming in ernest). I think you get the idea...of course, when Pa. shifts to Open Sky (yeah, right) all that goes out the window...
I just can't bring it out of the old EPROM right now, but there was something quite a while ago about a slim antenna that everyone was saying worked quite well (MFJ?? comes to mind...) Personally I have my doubts about something that small working at all on VHF lo. I'd also take a look at Northwest Radio's survey in the Antennas wiki, as well as some of the other links found there. Personally I like the Austin simply because it's so damn tough; it's been through several ice and snow storms with little more than a few scratches for the trouble. You can even cut the top whip for better reception on VHF lo band. I did, and it did make a somewhat noticeable difference (I cut it for 39 mhz - guess why? Awww, you peeked....). It's expensive but worth it.
If you can mount it on top of the roof with a good thru the roof mount, that's best. A trunk lip mount, like I use, will work just fine also, but not quite as good. If you use a trunk mount, make sure that the mounting screws bite right into the metal - the Austin needs a good ground. You can easily check this with a simple VOM - if you have a good path to ground between the mount and the car, you'll get a (nearly) full deflection on the meter. (I say nearly because there's almost always some resistance in the circuit. If you were to transmit through the antenna, I'd say use a couple of braid straps, but they're really kinda overkill in a receive application).
Mag mounts? Yechh. I avoid them like the plague. Scratches up the car, and as the magnet weakens over time, so too does the ground connection (which is capcitively coupled). Good for a quick fix, but not for a permanent solution.
In the meanwhile, let me see if I can remember that mini antenna everyone was harping about. I'll do a little digging tomorrow. 73s for now...Mike
 

ka3jjz

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I think I found the model everyone was harping about - the MFJ1721 and 1722. Avoid it. It's designed for 144/440 mhz and the other model has RG174U cable as its feedline, which is nearly worthless at 800. Stick with the links given earlier. 73s Mike

[edit] The Valor PMM3B seems to have something of a following - see the Antennas forum. Again, it uses 174u cable which can be a problem with loss (in fact, I cut the 174u cable on my mount back to 2 or 3 foot, then soldered together a good hunk of RG6. Difficult but worth the effort).
As always, your mileage may vary.
 
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bwhite

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Can't thank you enough for all of your advice.

It'll take me awhile to get thru the antenna forum, it is not one I usually visit,
I didn't know I needed one until our conversations and my experiments.

I hope you and yours have a wonderful Christmas.
 

bwhite

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Just a follow-up,
After looking over the sage advice offered it appears/ed that I have an antenna issue.
The antenna of choice from ka3jjz and the antenna forum sounds good and is priced well BUT the cable is only 9'; it ain't gonna make it from trunk to dash, I posted a question to see what others did about this, I'm not putting it on the roof.
I also saw some threads about a RS 800 rubber duckie with glowing reviews.
I realized that I think I have one of these from a friend, there is no label on it but I was not using it because it picked up badly on VHF-Lo. I tried it this morning and reception in and out of the car seems much better even in the previously mentioned RF HE##. I'll try for a few more days, but, I am curious about the antenna with the 9' cable, I'd hate to splice it to make it longer (thus adding to the losses), from the pic it doesn't look like you can swap out their cable, looks molded into the base.
 
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