Antenna Help - BC796D

[USAPatriot]

Howdy,

I'm in the Los Angeles area, have a new BC796D (am just getting back into scanning after many years) but the antenna I'm using is a simple 8' longwire hung horizontally across my ceiling. Works great for LAPD and other public service, but I'm missing out on a lot. 20 miles as the crow flies and I'm not hearing LAX or Burbank for example (using the unit's built-in service) though I can pick up Van Nuys. Admittedly I live in a hole but there's nothing I can do about that. I get virtually nothing from the Ham bands and couldn't find the military with a floodlight.

I can't go on the roof...(1) cost, (2) I'm disabled. So I guess I'm looking for an indoor solution but will still be hamstrung (no pun) by the cost factor. SSDI doesn't make one rich I'm afraid. Suggestions? Photos? Thx.

 

[JoeyC]

Sorry to burst your bubble, but an 8 foot antenna situated horizontally isn't going to be optimal for UHF signals. Antennas for 2-way comms are situated vertically and a length of antenna that size might give you decent reception of CHP on low band, but there isn't much else its optimized for. You're getting LAPD probably because you wouldn't need an antenna in the first place in your location.

 

[swest90]

I have the same issues from out here in Pomona. I have a 2 vhf verticals and a vhf beam for monitoring Pomona since they are still on vhf-hi and not repeated. I also have two discones all of this is mounted on the top of the roofline. I get great reception east and south but due to Kellog hill I dont get great reception out west, especially uhf. I am probabaly going to order a UHF yagi from comtelco sometime next week and hope that helps.

With your location a good discone mounted outside should work well for you.

Thanks
Shawn

 

[USAPatriot]

Sorry to burst your bubble, but an 8 foot antenna situated horizontally isn't going to be optimal for UHF signals. Antennas for 2-way comms are situated vertically and a length of antenna that size might give you decent reception of CHP on low band, but there isn't much else its optimized for. You're getting LAPD probably because you wouldn't need an antenna in the first place in your location.

I knew all that, which is why I posted my query

Swest: I can't do an outside antenna. Inside? Thx.

Edit: Would I gain anything by hanging my (ancient) longwire vertically rather than running it along the ceiling? Thx.

 

[KT4HX]

Hanging it vertically would be a start in the right direction. Given that you can't do an outside antenna, how about using a mag-mount antenna inside. Many people do that as long as you got something metal (i.e. file cabinet, air conditioner, etc) to stick it on. You could even have a couple different ones in your room run thru a switch so you could swap out depending on what you want to listen to (LAX or LAPD). Or just swap them on the back of the 796. Just one idea to try.

 

[Andy128]

I have a BC796d also- I have my unit in the basement and would like to improve the antenna / reception. I know knothing about antennas or connectors and stuff. What is the 8" wire and how does one connect it?
I can have an outside antenna- what kind should I get?

Andy

 

[PluckyPleco]

Yup

Would I gain anything by hanging my (ancient) longwire vertically rather than running it along the ceiling?

Almost everything you want to listen to with a scanner is going to be vertically polarized.

You can lose up to 30 dB (only getting 1/1000th of the signal received with proper polarization) by not having your antenna oriented correctly.

But enough theory... Try hanging your 8' wire vertically rather than horizontally and see what difference it makes!

Plec

 

[USAPatriot]

It made some difference but it's not huge.

How much coax can I run with a discone? I suppose I could find a few people to help me get it up and my 25 foot mast is still in place. I set it in concrete when I was a CBer back in the early/mid-70's. Thx

 

[KT4HX]

That would be great if you can get some assitance to put a discone up. I think you would see a nice improvement over what you have now. Two very important things to consider are the quality and length of the coax. You want to utilize the best quality cable you can afford (something like LMR-400 or 9913 are good choices), and keep the length to what you need to get the signal in to your scanning position, without excessive overage. You want to have some wiggle room, but you don't want a lot of cable coiled up behind the desk either. Remember, the longer your coax and the higher the frequency you monitor, the greater the potential for signal loss, and that you want to keep to the minimum possible. Good luck with your project and let us know how it works out for you.

 

[USAPatriot]

At what length does it become a problem? I'd pretty much resigned myself to buying 150ft and chopping everything not needed to reach anywhere in the room, but if even that's too much line, then maybe I'd need to look at the (supposedly) better Scantenna rather than a discone. Thoughts? Thx.

 

[KT4HX]

While I haven't used a Scantenna myself, I know a lot of people really like it. So I would say it would be a better bet than the discone. The length at which loss becomes a problem really is a factor of the quality of the cable and the frequency you are monitoring. Try this link for a coax loss calculator to get an idea of what I am talking about.

http://kc7hxc.us/links/radio/Coax Calc/Coax Calculator.html

 

[nexus]

this link will give you loss/per foot @ frequency information (very useful)
http://hamradio.arc.nasa.gov/coaxcableloss.html

You want to try to keep your feedline as short as possible. Under 100 feet if you're
fooling with Belden 9913/F or RG-8U. If you're using cheap stuff like RG-58 then you
will want it to be less than 30 feet in lenght.

@ 100mHz Belden 9913/RG-8U has a loss of 1.3 dB per 100 feet.
@ 700mHz Belden 9913/RG-8U has a loss of 3.6 dB per 100 feet.

That right there gives you an idea. If you can get it at 50 feet or less you're going to do real good around 800mhz and almost perfect at VHF. The closer you get the dB loss to ZERO the better. You might want to also not use PL-259 connecters. Use something designed for higher frequencies like TNC and BNC for the radio end.

 

[USAPatriot]

Good answer, thanks. Running RG6 at 150 feet results in an additional 3 db loss versus a 100 foot length. That's for tranny not receive but is a good comparison anyhow. LMR400 cuts that loss in half...this at 483 Mhz. Thx

 

[Al42]

Good answer, thanks. Running RG6 at 150 feet results in an additional 3 db loss versus a 100 foot length. That's for tranny not receive but is a good comparison anyhow.

Sort of. Since the SWR is always going to be higher with a scanner as the load, as compared to a resonant antenna as the load (the transmitter is the source when transmitting - the antenna is the source when receiving), the loss when scanning will always be higher, except at that frequency at which the scanner presents exactly a 50 ohm load to the cable.

 

[USAPatriot]

Well, I'm getting close.
The Scantenna will arrive sometime tomorrow. Yesterday evening I collapsed the mast and took down the TV antenna that'd been put up in place of my old Super Penetrator when I went into the USAF back in 1978. *I* meaning me watching mostly while a few others did the actual grunt work. The temp here is getting ready to spike again but may be down into the 70's again by mid week so it shouldn't be too much longer. Thanks for all the advice -Rod-

 

[USAPatriot]

I guess I counted my chickens before they hatched. UPS showed up this afternoon and the delivery guy asks me if I wanted to have him declare the package damaged. Well...duh! Judging by the odd angle of the box it was pretty evident that some yutz had dropped something on it. And yeah, the antenna looked like it too. UPS is returning it, the seller, Antenna Warehouse, is shipping me a new one. Hopefully UPS will treat the new one better than this one. Jerks

 

[USAPatriot]

Back to square one. The seller reshipped me a new Scantenna yesterday, which means it'll be next month before I see the damned thing. UPS still hasn't bothered to pick up the one they wrecked. Inbred idjits...

 

[USAPatriot]

Hot ****! The new Scantenna arrived about noon today (in one piece and unbent even) and I managed to get it put up in 7 hours. I couldn't get help on short notice (woulda been almost 2 weeks) so had to do it myself. There's a REASON why I'm not supposed to go up on roofs and I damned near got the reminder in a bad way. I lost my balance and sat down. Luckily I pointedly made sure I always kept my back to the top of the house so when I went down I actually went up. If I'd been turned around I'd have hit concrete. I guess it's why they call it "disabled"...I just mostly refuse to give in to it
Got it all together and up 25-30 feet, ran a single run 150 feet of RG6 and only have 20 feet left over - not bad! The signal is amazing. Most of LAPD now pegs the 796's meter at 4-6 bars where before it was 1-5. There's a few 1's in there still but there's so little static that I'm having no problem hearing it all. Instead of a crackle there's just a light bit of hiss. I didn't run a grounding block... But for tonight I'm too damned tired and sore to care much about what's going on, so I guess I'm going to take a pass on this friday night's action. Thanks for your advice and good answers. -Rod-

PS...Antenna Warehouse's behavior through all this was impeccable. Tim gave me no hassles about having to send out a new antenna after UPS trashed the first one, and he did so before he had proof (other than a photo I emailed to him) that there was a problem. He made good on it and didn't complain. UPS is gonna be on my **** list for awhile though. Yesterday they went up the street with it in their truck only they didn't drop it off. Somehow it went unnoticed

 

[Al42]

Hot ****! The new Scantenna arrived about noon today (in one piece and unbent even) and I managed to get it put up in 7 hours. I couldn't get help on short notice (woulda been almost 2 weeks) so had to do it myself. There's a REASON why I'm not supposed to go up on roofs and I damned near got the reminder in a bad way. I lost my balance and sat down. Luckily I pointedly made sure I always kept my back to the top of the house so when I went down I actually went up. If I'd been turned around I'd have hit concrete.

I'm relieved that you're (relatively) unhurt. If you feel that foolish again, tie a rope around your waist, with the other end tied around something secure, like a chimney.

I didn't run a grounding block... But for tonight I'm too damned tired and sore to care much about what's going on, so I guess I'm going to take a pass on this friday night's action.

At least disconnect the antenna from the scanner for now.

 

[USAPatriot]

It's probably not possible to install a grounding block at this point, Al. I don't have the tools to be cutting the coax and the excess is currently coiled under my bed. The mast is grounded and that part should be ok. I put in it 35+ years ago I supposed I could put in a grounding block inside and run a wire back out. Otherwise there's little to do. -Rod-