A question I’ve received several times since sharing my last field activation with the MTR-4B is “why do Mountain Topper radios have three individual band switches–?”
That’s a great question and the answer is actually in the product manual.
The following comes from the MTR-3B manual but also applies to the MTR-4B (save the 4B has four band positions instead of three):
The band is selected by three, three position slide switches. For proper operation, all three switches must be in the same
column[…]. It’s easy to get into the habit of flipping each switch in sequence from the top down.
The top switch tells the processor which band to operate on and connects the Receiver input filter to the first mixer. The
middle switch connects the transmitter low pass filter output to the antenna and connects the antenna to the receiver
input filter. The bottom switch connects the output of the transmitter PA to the low pass filter.
The manual is correct: it’s easy to get in the habit of sliding all three switches with band changes. It becomes second nature in very short order.
It’s easy to tell that all of the switches are in the correct position as well because without all three switches selected, the receiver sounds deaf and audio muted. With them in position, the receiver sounds “alive.” (That said, the noise floor is so low on these radios, it’s quite possible you might think they’re not engaged properly if there aren’t many signals on the band!) Of course, it’s very easily to visually inspect the switches and confirm they’re in the correct position.
Side note: On the Mountain Topper series, each band switch is an independent mechanical switch. On the Venus SW-3B (which was no doubt inspired by the Mountain Topper) the two band switches are bound together as one:
You can’t tell from looking at the photo above, but if you slide the top switch, you’re also sliding the bottom switch: the two switches are only one mechanical piece. An interesting design choice!
Side Note: The (now discontinued) Mountain Topper MTR-5B had a more complex series of six switches. Here are the instructions for it along with a drawing from the MTR-5B manual:
I hope this helps clarify how/why the Mountain Topper series uses multiple switches for band changes!