TreeSeeker -
1. Furnace vent screens:
I think it's a brand difference rather than old versus new. My '69/70 M300 Class A had the one piece intake/exhaust 'bezel' versus what your picture showed. Mine could have been a retrofit, possibly with more BTUs for Alaska's weather. (I've encountered a snow shower at sea level on a Memorial Weekend.)
Mine was definitely old, based on what I encountered when I pulled it to renew the wiring and increase wire size on its 12VDC side. (It had a transformer, rectifier, and relay to automatically switch to 120VAC when plugged into shore power.) I don't recall if a fault or wire appearance caused me to rewire it.
2. Power converter and coach (house) voltage.
13.5VDC (plus or minus several tenths of a volt) is 'standard' when the engine alternator is active. Likewise, the North America standard for household voltage encompasses a range. (I don't have the figures at hand but seem to recall 107VAC as the bottom end of the range for being within standards ... similar variance on the top end of the range.)
Most electronics made for motor vehicles have internal regulators for 'smoothing out' input voltage. This is in recognition the voltage from a vehicle battery/alternator system varies by several volts.
Old style (cigarette lighter) power supplies/chargers (for laptops, etc.) had similar regulator/filters. The USB standard tightened up the acceptable range and the standard is firmer. (The USB standard is driven by industry concerns and demands.)
Blue Sea Systems offers (at least) two USB outlets for cell phones, laptops, and so forth. The less expensive one is more generic while the more expensive one has sensor circuits for adjusting output for some (mostly Apple) devices. (IIRC, the USB standard includes 'talk back' capability for intelligent chargers, although not all manufacturers use it.)
If you opt for an additional regulator, you want an electronic regulator/filter made for that purpose. An engine voltage regulator won't work for this purpose. (Engine voltage regulators govern the input voltage to the alternator's field rather than the alternator's output.)
I'd recommend a new power converter and strongly suggest the brand Leeann has. My logic is why spend money to 'fix' possible problems with an old converter ... a new (modern) converter eliminates the possible problems.
I recently took an in-depth look at what Leeann has and really like what I found. Based on what I saw, I've thrown some of my SOP practices out the window. (I tend to be an immovable dinosaur, wary of 'new and improved' technology until it's proven ... so that's significant.)
