I have a Wards Airline 84HA-2727A radio/phono that's been recapped, etc. 15 tubes, 15 inch speaker. Works fantastic on FM and SW with built in dipole and loop antenna, but- On Am I get nothing but very loud 60 hz hummmm. I disconnected the loop and connected to my long wire antenna outdoors and get no hum but only get one station in the middle of the AM dial. Also SW is still very good. My question is this- Does the loop need to be still connected to function with the external antenna connected?Is it part of the tuning circuit? There is also the possibility that the loop connections are connected wrong. There are four wires(no plug) and someone removed them and labeled the wires but may have got them wrong. Also, is there anywhere I can find an operating manual for this set? The chassis was made for Wards by Hallicrafters.

Schematic: http://www.nostalgiaair.org/Resources/v ... 011828.pdf
It's a complicated setup, but I would say yes, the loop needs to be connected for reception on the broadcast band, whether or not an external antenna is used.

The loop antenna has two parts, referred to in the diagram as primary and secondary. The primary is just a turn or two that serves to couple the external antenna to the secondary when on the broadcast band. If the loop antenna is missing or disconnected, the signal from the external antenna has no way of getting into the radio.

In the shortwave bands however, the bandswitching sends the external antenna signal in via a different route and not through the loop antenna.

It looks like you're going to have to trace out the wiring to ensure the loop connections are correct. Incorrect connections could certainly cause the symptoms you describe.

That chassis is made by Hallicrafters. I've had the Hallicrafters metal can version and it was good performer. The speaker should be a high end Jensen. In this case, you will need the loop antenna.

Thanks to all for the advise. It turns out that the loop does have to be used but was connected backward putting the antenna loading coil into the secondary, not the primary of the loop antenna. I traced down the buzzing sound to having my computer wireless modem too close to the set. Pulled the plug on it and that all cleared up. It only messes with AM though so I'll flick it off when on that band. I'm getting lots of AM stations now even without the long wire but have left it on as it does help SW bands.
Yes it does have a 15" Jenson speaker and sounds fantastic! I will post new thread this weekend with lots of pics.