Instruction: Given a question and the related document, and generate the answer to the question based on the information provided in the document.

Input:
Question: What model AC Adapter is compatible for this radio?
Document: I have used this radio a lot since I purchased it, and it does have a hardy appetite for batteries when played at high volume. Accordingly, I purchased an AC adaptor for it. I tried several adaptors before I settled on the Radio Shack 4.5 volt &quot;International&quot; model (cat. no. 273-1759). This device accepts almost any input voltage and frequency and produces a full amp of filtered, regulated DC. Unlike other adaptors I tried, this one is relatively &quot;quiet.&quot;  It does not induce hum or electrical noise.
A word about AC adaptors:  Cheap ones will generate an annoying 120Hz hum because they don't filter the AC adequately. No problem with strong local signals, but it will wipe out the weak stations. Either get a very good one, or stick with bateries. Also; consider getting a slinky type SW antenna. They can be had for under $20 and will increase your SW reception tremendously. All you need to do is hang one up and clip it to the telescoping antenna on the radio.
However, this radio turned out to be virtually impossible to disassemble and repair with reasonable effort and tools that I had at home, so I ended up getting a different model from RadioShack.
This little radio does not meet my expectation. Although it performs all right on FM ,it does fairly poor on SW and that's what i wanted to use it for. Of course I realise that's not the top of the line but I was expecting better reception on SW.I should have chosen a better model.
It's hard to believe that you can purchase so much performance for less than $40. This little radio has the ability to fill a large room with undistorted sound from any of its 12 bands. Moreover, it is quite easy to use. Sensitivity and voice clarity are remarkable. The automatic gain control deals nicely with weak and strong signals. Selectivity is quite good, but one could use a larger tuning knob (or I suppose in my case, smaller fingers) to make those fine adjustments easier. The size of the radio makes it easy to pack.Although you get a lot of radio for a few dollars, it would have been nice if Sangean had included an AC adaptor.
This fails the effort/reward equation, this fails the cost/reward equation, and even when it lands a signal, it's the audio equivalent of watching a snowy TV screen. Don't abandon the idea of trying shortwave radio, but please, walk up the ladder to a better, higher priced model that will deliver enough listenability so that you or your kid can make an informed decision on pursuing this further.
Listeners in the Southeast can pick up normal AM stations all over the Carribean and Central America on this radio at night. My earlier model has more weight to the body, but I don't erally know that it's any sturdier. Modern plascits are prety strong. Also, Sangean's equivalent of this radio back in the 80s cost more like $85 back then. We're getting much more value now. It's not much to look at but this is really a fine, inexpensive, radio for listening to the world. It's cheap enough that it won't break your budget.
But where's the fun in that I ask you?After much research (including reading many reviews here on Amazon), I decided to go with this Sangean model. Honesstly, I wasn't expecting much for the price. I figured that since it was the most inexpensive model, it would be just a very basic, mediocre machine. Boy was I wrong! Just last night I used the machine for the first time. As opposed to the usual deluge of biased, boring American news programs, I was enjoying braodcasts by the likes of the BBC, Voice of Russia, RAI, Radio Netherlands- to name just four!So what if the stations were sometimes a little fuzzy and went in and out?
The radio is sensitive to any excellent signal but has more difficulty with good or mediocre signals that other sets such as much Sony ICF-SW7600GR or older but good shortwave units can make audible for listening. Selectivity(the ability to to keep powerful neighboring stations, some 10 to 15 kilohertz from crowding out good to mediocre signals) is a big problem at times with this model. I have had problems with more powerful local shortwave signals interrupting other signals that can be heard on the other shortwaves I have. So, I therefore give the radio a "C"  and "C-" to "D+" for its sensitivity and selectivity on the shortwave bands.On AM or the Middlewave band the radio is decent for its sensitivity and selectivity.
I bought this radio as a replacement for the Kaito KA11, which inexplicably stopped working in the AM/MW band and gave me concerns about Kaito's quality control.This is a basic shortwave/FM/AM radio, large enough to provide decent room-filling sound yet small and light enough to fit into a backpack. As I am going on a trip to Asia and will be going to places where shortwave radios are banned, it's also cheap enough to leave behind somewhere.There aren't many bells and whistles on this model: no exact frequency readout, no sleep timer, no alarm, no presets, no "wide" or "narrow" filter, no treble and bass settings, no external antenna jack, no tuning outside the basic FM/AM and shortwave broadcast bands; not even a carrying case.
Answer: Mine takes 3 AA batteries, so its a 4.5 volt system. I don't have an adapter because I don't use it inside. I love it because it's "portable." Great little radio. Picks up everything. I used it when hiking and camping on the Appalachian Trail. Just put 3 new AA batteries in it, and it will run for countless hours.