While there could be issues with the antenna, and you may think it's an antique, there is no such thing as a "digital TV" antenna.

I looked at the antennaweb.org website for the general DC area but looks like reception issues vary greatly depending on location.

Please post your zip code and I'll be more than happy to take a look again and offer any ideas or suggestions.

The zip is 22306.

Is there anything different in the way that Fox and NBC package their signals. I found it curious that I can get a nice signal for 1 pair of channels, but with 2 other channels at essentially the same distance and direction.

You're probably using an old VHF antenna. Try a VHF/UHF antenna.
It looks like the ABC and CBS stations are transmitting on the VHF frequencies, channels 7 and 9, but the FOX and NBC stations are transmitting on the UHF frequencies, channels 36 and 48.
Even though you TV says that NBC and FOX are transmitting on channels 4 and 5, they are actually transmitting on channels 48 and 36.
Take a look at the enclosed link.

Here is a link that might be useful: DC Television Stations

As jimisham pointed out, you do need a VHF/UHF antenna, but I'd be surprised if you had a VHF only antenna. Does it have wide elements at the back end (for VHF) with very short elements at the front end for UHF? Does the coax cable (unless it's flat 300 ohm twin lead) look good and not dry and old?

However, the thing that I found amazing was that looking up your zip code on antennaweb.org required a near fringe antenna for some stations 15 miles away?!! Say what?!

Your ABC & CBS stations actually share the same transmitter tower and are on (real) VHF channels. NBC & FOX are very nearby on separate towers on (real) UHF channels. The "displayed channel" is a "virtual channel" only and is used to keep the stations historical channel intact.

I plugged in a couple nearby zip codes and reception is all over the place.

I'm not familiar with the area but I assume, and from what I remember from visiting the DC area, that it's relatively flat so there must be an issue with "urban congestion" or tall buildings blocking and reflecting signals.

Kinda stumped right now but if there's any info you can add maybe I can come up with something. Post back with your antenna type & lead-in wire info, antenna mounting & height, terrain & surrounding structures, and maybe I, or somebody else, can come up with some ideas.

Thanks for all of the great responses.

The DC area is relatively flat, but I do live in a bit of a "valley" there's a stream behind my house, so, it's kind of a low area with a hill to the north between me and the TV towers.

I would say that the Coax is dry and old. Not sure I want to stand on a ladder on my roof and climb 10' above the roof to replace it. Sounds... dangerous.

Here is a link that might be useful:

RCA ANT700R at Walmart suggested by yosemitebill above gets 13 -14 stations - according to spouse. works very well in some remote places like Carson City, Nv.

Wow!! That is one of the Coolest, most "Gothic Looking" antennas that I have ever seen!! The chimney, grey sky, and bare tree only adds to it. Got to love the "Bat Wings" on one of the front elements as well!

In all seriousness though, that is a VHF/UHF antenna which looks like it was made for about a 20-30 mile reception range - which "should" meet your needs. Again, the recommendation from the antennaweb.org website really says that something is just not right here.

I would suggest an antenna pre-amp, which unfortunately, the amp is mounted up near the antenna, with the power supply connected in the house. The power supply sends the power up the coax to feed the amplifier.

Of course this would be climbing up on the roof to the antenna, which you said you'd rather not do. If you did, then I'd recommend changing the balun (transformer) at the antenna and lead-in coax.

Albert's suggestion about the RCA antenna from Walmart might be something to consider. You still have to get it up on the antenna mast, but it has a built-in pre-amp, and might get those other stations. And, if it didn't work, you could always do, in the Walmart tradition, return it!

It's also possible the cable connections at the antenna are corroded.

Is it coming into the house as flat lead or round cable?

It may need a convertor (balun transformer) somewhere. If the antenna has 300 ohm leads coming out of it, but 75 ohm round cable coming into the house, that transformer should be up at the antenna.

I realize all these things involve going up on the roof, but it is what it is. Can you stand on the roof and somehow lower the mast to you rather than going up to it?

It's round cable all the way down from the antenna.

For the record, I don't mind going up on the roof. But, I am not comfortable putting a ladder on the peak of the rook near the antenna, and then going up that ladder.