Old-timey antenna question.

Factual Questions
1

I have one of those old rooftop antennas on my house that was probably installed in the 50’s or 60’s.

It looks like this. Well, not exactly like that but it’s one of those old monstrosities. A TV antenna.

Let’s say I want to run this antenna into the “antenna” plug on my new HDTV receiver. With the information I’ve given you, can you comment on the compatibility of this? I know that rooftop antennas CAN pick up the appropriate broadcasts. It’s not that I’m worried about. I’m worried about whether I can actually attach the antenna to a receiver.

Would the componentry be too out of date?

Currently, the antenna has two “flat wires” coming off it that were just sliced by someone at some point in the past. Up near the antenna, a little box encases each wire. I’m not sure what those boxes are for.

Also, can I get an FM radio signal out of it?

Thanks.

2

Ths is the important bit of information. You need an impedance transformer to match the 300 ohm flat wire to 75 ohm coax input of modern equipment. You can get them for a few dollars at radio shack. Get the kind for outdoor use that look like a long cylinder and weather seal the connections. You can also use this antenna for FM which is in the same band as VHF broadcast TV.

3

Oh, if the antenna has two pairs of wires then it’s likely that one is from a separate UHF antenna. You’ll want to use a combiner if you want these channels. The UHF antenna will have smaller dipoles, the antennaey bits.

4

Sounds like 300-ohm twin-lead cable. You can replace it with the same type of cable, or 75-ohm coaxial cable and a 75/300-ohm balun. I’d switch to coaxial cable, it is less fussy about how it is routed. Your local Radio Shack or similar store has all of the parts you need.

It probably works for FM too.

5

As expected, you’ve now raised MORE questions.

It has two of these flat wires. Is that what you’re calling two “pairs” of wires. I THINK that each of the wires looks kind of like this: o–o that is, a wire, some plastic and another wire.

It SOUNDS like what you’re telling me is that one is VHF and one is UHF (and I’d need to determine this up at the roof).

If that’s the case, what’s my move. . .

Most important: for HDTV “antenna in” : do I get an impedance transformer and just work on the end of the flat wire or do I need to do something on the roof? That sounds easy. I’ve stripped wires and set up lamps and plugs and switches before.

For FM : Do I use the same wire and just split it at some point?

For UHF (which I also can receive in Baltimore) : Is that the OTHER wire? Can I also get an impedance transformer? If I’m already using the “antenna in” on my HDTV receiver, am I SOL or is there a way to run the VHF and UHF into the same CO-AX? Padeye mentioned a “combiner”.

Is there a way to tell the 300 OHM from the 75 OHM?

Finally: let’s say I wimp out, and decided to call someone. Does any electrician know how to do this stuff? Should my dish installer know how to do this stuff?

Thanks. Mucho appreciation.

6

Sorry.

One of you said the two wires were “VHF and UHF” and one of you said “300-ohm twin lead cable”.

I think mks was just saying each wire was “300-ohm twin lead cable” and putting that together with what padeye said, I take that to mean that one is VHF, one is UHF and they’re both 300-ohm twin lead cables?

7

Yes. The the o-o is one antenna “wire” comprised of an unshielded 300 ohm flat cable with 2 wires. You have two of these wire sets connected (at the antenna) to the separate UHF & VHF element sections of the antenna. The VHF connection will lead or be connected to the section with the longest elements on the antenna. The section with the relatively shorter UHF section elements will attached to the other block. VHF or FM sections are usually distinctive swept wing or fixed wing style dipoles. The UHF antennas sections can come in several different shape configurations, but are often at the “tail” section of the VHF wing.

Beyond corrosion on the antenna and connections after decades of exposure, you may get an acceptable HDTV signal but don’t count on it.

MAKE SURE THE ANTENNA IS GROUNDED TO A LIGHTNING ROD OR OTHER EARTH GROUND BEFORE ATTACHING IT TO YOUR HOME ELECTRONICS.

8

That sounds right to me. The flat ribbon-like cable is 300-ohm twin-lead.

The VHF antenna covers channels 2-13 and FM.

The UHF antenna covers channels 14-83, which also includes ATSC HDTV, which is currently broadcast on the UHF band.

You can run two separate cables or combine them into one cable with a VHF-UHF combiner.

9

OK, it looks like I’ll need to hook two of these up to the antenna (one ofr UHF, one for VHF), run a section of coax out of them, and then add one of these to combine the two coax cables, which I can then run into the cable box.

Sounds like fun actually.

I hope the antenna isn’t too corroded.

Thanks for the info on the grounding wire. What will this look like? Just a long wire coming down to the ground from the antenna. Isn’t this something the original owner should have done?

10

This is what you need for your antenna. The flat wires (300 ohm) need to be converted to standard coax cable (75 ohm). That is what the matching transformer does. Connect the flat leads of the transformer to the screw connnections on your antenna where the current flat wires are connected, then run coax cable from the antenna to the “antenna in” port on your satellite receiver.

Any HDTV signals will be on the VHF side. You can ignore the UHF portion of the antenna, unless you have no other way to receive your local stations that broadcast on channels 14-83. (Remember, if they are broadcasting digital signals it will be on the VHF side).

If you need an antenna for your FM receiver, you can always put a splitter in the 75 ohm coax cable at your receiver end, and connect another transformer to one side of the splitter for your FM signal (which is also in the VHF band).

11

That is incorrect. Almost all of the HDTV signals are in the UHF band. I live in Maryland and have a HDTV receiver, so I can verify that fact.

12

Re the ground wire it will usually be a solid metal exposed (unjacketed), relatively thick copper or aluminum wire attached to the antenna or pole.

Some potentially helpful links

See also Antenna Help - TV Antenna FAQs

Here’s a likely looking HDTV messge board that may be helpful

Home Theatre HDTV

13

From the first FAQ link

14 


Call Sign     Actual Ch.   Location         Displayed Ch.
WMPT          42           MD Annapolis     22
WMAR          52           MD Baltimore      2
WBAL          59           MD Baltimore     11
WJZ           38           MD Baltimore     13
WUTB          41           MD Baltimore     24
WBFF          46           MD Baltimore     45
WBOC          21           MD Salisbury     16

As of 10/2003

15

Right. Both are 300 ohm twin lead, one each for UHF & VHF. You can combine them and convert to coax down in your living room right next to the HDTV.

Or, for a LOT more trouble, you can do the conversion up at the antenna and string new coax from the antenna to the TV. You might get a somewhat better signal that way. My advice would be to do it the easy way & if the picture’s not too snowy leave the current wiring alone.

16

The current wires are severed. Not sure who did it. Maybe the cable man years ago. The TV isn’t using them right now, so I figure I’ll do the work at the antenna OR get the installer to do it.

Here’s a list of what antennaweb.com says I should be able to get. dont’ worry about what the colors mean.



yellow - uhf WNUV 54 WB  BALTIMORE  MD  258° 7.3 54
 yellow - uhf WNUV-DT 54.1 WB BALTIMORE MD  314° 1.0 40
 yellow - vhf WJZ 13 CBS BALTIMORE  MD  307° 1.0 13
 yellow - uhf WJZ-DT 13.1 CBS BALTIMORE MD  307° 1.0 38
 yellow - vhf WMAR 2 ABC BALTIMORE MD  308° 1.0 2
 yellow - uhf WMAR-DT 2.1 ABC BALTIMORE MD  307° 1.0 52
 yellow - vhf WBAL 11 NBC BALTIMORE MD  307° 1.0 11
 yellow - uhf WBAL-DT 11.1 NBC BALTIMORE MD  307° 1.0 59
 yellow - uhf WBFF 45 FOX BALTIMORE  MD  314° 1.0 45
 yellow - uhf WBFF-DT 45.1 FOX BALTIMORE MD  314° 1.0 46
 green - uhf WUTB 24 UPN BALTIMORE  MD  258° 7.3 24
 green - uhf WMPB 67 PBS BALTIMORE MD  327° 11.3 67
 green - uhf WMPB-DT 67.1 PBS BALTIMORE MD  327° 11.3 29
 lt green - uhf WUTB-DT 24.1 UPN BALTIMORE MD  258° 7.3 41
 red - uhf WMPT 22 PBS ANNAPOLIS MD  187° 22.1 22
 red - uhf WMPT-DT 22.1 PBS ANNAPOLIS MD  187° 22.1 42
 violet - uhf WFPT 62 PBS FREDERICK MD  278° 37.9 62
 violet - uhf WETA 26 PBS WASHINGTON DC  236° 35.6 26
 violet - vhf WJLA 7 ABC WASHINGTON DC  233° 35.4 7
 violet - uhf WCPB 28 PBS SALISBURY MD  150° 85.9 28
 violet - uhf WDCA 20 UPN WASHINGTON DC  236° 35.7 20
 violet - uhf WFDC 14 TFA ARLINGTON VA  233° 36.0 14
 violet - vhf WTTG 5 FOX WASHINGTON  DC  234° 35.2 5
 violet - vhf WRC 4 NBC WASHINGTON DC  233° 36.0 4
 violet - uhf WHUT 32 PBS WASHINGTON DC  236° 35.7 32
 violet - uhf WNVC 56 IND FAIRFAX VA  236° 44.5 56
 violet - uhf WBOC 16 CBS SALISBURY MD  147° 77.9 16
 violet - uhf WBDC 50 WB  WASHINGTON  DC  231° 32.9 50
 violet - uhf WMDT 47 ABC SALISBURY MD  150° 74.8 47
 violet - uhf WMJF-LP 16 A1  TOWSON  MD  28° 4.8 16
 violet - vhf WUSA 9 CBS WASHINGTON DC  233° 35.4 9

Fortunately, the DC stations are sort of along the same line (287 vs. 233). I don’t know if that’s a big enough difference.

Here’s the digital only stations. All UHF. And all from pretty much the same place. I suspect that whoever set the antenna up in the first place pointed them in the right direction.



* yellow - uhf WNUV-DT 54.1 WB BALTIMORE MD  287° 1.2 40 
* yellow - uhf WJZ-DT 13.1 CBS BALTIMORE MD  282° 1.3 38 
* yellow - uhf WMAR-DT 2.1 ABC BALTIMORE MD  282° 1.3 52 
* yellow - uhf WMPT-DT 22.1 PBS ANNAPOLIS MD  188° 22.4 42 
* yellow - uhf WBAL-DT 11.1 NBC BALTIMORE MD  282° 1.3 59 
* yellow - uhf WBFF-DT 45.1 FOX BALTIMORE MD  287° 1.2 46 
* lt green - uhf WUTB-DT 24.1 UPN BALTIMORE MD  257° 7.8 41 
* violet - uhf WMPB-DT 67.1 PBS BALTIMORE MD  325° 11.3 29

Nothing from DC.