Going back to the original problem -- horrible reception on AM is likely to be because cheap radios use small "bar" antennas (wire around a coil) that aren't very effective, and daytime AM reception is often limited to ground wave due to daily changes in the maximum useable frequency for ionospheric refraction (MUF). AM reception will always be better at night.
If there is an external connection for an antenna, sometimes it handles both bands and sometimes it's only handling VHF (FM).
If the antenna connection checks out good and it isn't all rolled up in a ball behind the radio, and AM reception is still very poor at night, check for local interference sources including the converter itself.
Kill the AC power to the converter and run off of battery and if the AM reception goes up markedly, the switching power supply in the converter is generating RF noise or something else on and operating when AC is present is making RF noise.
Fighting this source of "common current" noise usually has to be done by both cleaning up the source of the noise or attempting to block it getting into the radio on the power leads with ferrite beads.
As far as VHF/FM goes, VHF is essentially "line of sight" from the broadcast facility antenna to you and many campsites are just in the middle of nowhere and not in the intended RF coverage area. (Same goes for VHF and worse, UHF HDTV signals, thus the use of amplifiers on RVs.)
Comparing the RV reception to another receiver may show if there's a marked difference, since it's unlikely even these cheap stereos in RVs have less sensitivity (although they likely have poor selectivity, which are the two things that are "trade offs" in any radio receiver design) and most use the same single chip or dual chip chipset receivers where the manufacturer only has to choose a power source and filtering, RF "front end filtering -- which is likely close to nil on these units, and gain desired. (As in amplification. Amplifiers amplify both the wanted and unwanted signals and careful planning is necessary for very high performance receivers. Which, one assumes, these cheap units are not designed for.)
Best you can do are these things in this order:
- Make sure any antenna provided is not coiled up behind the unit.
- If the unit is using the external TV antenna and RF pre-amplifier and you're in the boonies with few RF noise sources, then make sure the pre-amplifier is on.
- If the unit has a built in wire antenna and also external antenna connections available, make a better antenna (a half wave dipole will do fine) and get it stretched out inside the cabinet or vertically behind it, etc. In other words, increase the "capture area" of the antenna. Going larger than a half wave dipole probably isn't going to really help much without building something highly directional for VHF and won't help at all on LF/AM signals.
- Eliminate possible noise sources in the trailer itself since everything is sharing a common ground and likely a floating one, depending on whether you're hooked to a pedestal with AC, I you're running from a (possibly horribly noisy at either frequency, but probably not both) generator. Try running from battery only with everything else turned off in the trailer (especially motors of any sort -- furnace blower, water pump, A/C, at least as a starting point for a test, and eliminate them as noise sources one by one) and see how it sounds.
- Last but not least, every once in a while one of these radios leaves the factory misaligned. Not often, but quality control on this Chinese made electronics junk isn't high. We had a car stereo, a "premium" upgrade in fact, that simply wouldn't receive AM broadcast well in a brand new car once -- we had to arrange to show the sales manager in person at the dealership by daring him to let us park our vehicle right next to an identical vehicle with the same "high end" stereo system on the lot and let him listen with a direct A/B comparison. Once he heard it, he had a service tech listen and authorized him to contact corporate and swap out the radio, which on this particular car was no small feat because the radio itself housed vehicle specific data for the on board computers and a swap required a new radio be programmed with the vehicle's data. Not cheap at all, which is why he balked until we asked for the comparison.
At least you're not dealing with something like that. These are just cheap car stereo guts inside these RV radios, reminiscent of 1980s/early 1990s tech. They're almost throwaway.
One other option: Any good car stereo shop can help troubleshoot the problem and many will work on RVs. Be prepared however to get a sales pitch for an upgrade. If you REALLY like music or other radio when camping, just about anything a car stereo shop might offer in terms of upgrades to both the head unit and the speakers will almost guaranteed sound better than the stock system.
And if you're the DIY sort, you can do some online shopping and do your own upgrades. Speakers are the first place to go -- the stock speakers are as cheap and flat sounding as flat can get.
Some Keystone units have subwoofers to help cover up the horribleness of the stock mid/tweeters in the roof and outside, but many don't. If you don't mind the additional power draw, they're a nice option. A good quality "sound bar" under the TV wouldn't be awful as an option either, and could be wired to the stereo also.
In all, I consider my stock system in my trailer to be pretty "meh" on audio quality, RF reception capability, and overall usefulness, but it works to augment the TVs tinny internal speaker and give a slightly fuller audio experience. I don't expect too much of it, though. I've installed $100 worth of car stereo speakers better chosen than the ones Keystone uses, and $100 stereos that singly or combined, sounded better than their low end stock stuff.
If I want to listen to quality tunes at night camping, I put on the headphones and hook them to a mobile device. If we are in data service range of cellular data, I keep a line in aux cable handy and feed whatever I want to listen to into the stock stereo if I don't want the headphones on. About the only time the stock stereo is used for radio reception is as background noise when cooking or similar and rarely even then. It of course is the amp for TV audio and augments that, but I wouldn't say that it sounds "good".
There's my $0.02... Add $4 more and it'll get ya a Starbucks coffee. Haha.
External radio antenna???
Linear Mode
