[HBR] Note on 1600-1700 kcs IF frequencies

[Walt Hutchens]

http://en.wikipedia.org/wiki/Highway_advisory_radio
> 
> Sure enough, as the above link points out, there are FCC set asides
> for Highway Advisory Radio, starting from 1610 kcs on up to 1700.
> One may want to be aware of this. My hope is that there isn't one
> around my neck of the woods that would cause a Q-R-Nancy. If it gets
> too much of a problem, I can possibly see this phenomenon chasing us
> clear into the 160 meter band, which opens up a new can of worms ...

I think this is less a problem than it appears to be. First, these are
low power stations: They are intended to be audible only while on a
particular stretch of road, typically with an antenna that runs along
that road; there are specific restrictions on signal strength at
distance. And I know these stations vanish almost immediately when you
get out of the relevant stretch.

The link given above has much more information -- it's worth a read,
since this IS an issue we have to live with.

Second, the 1st IF does have some protection against 'breakthrough'
from the RF stage, which (except on 160M) would be tuned to a
considerably different frequency.  This protection is particularly
good for HBR-type receivers which have unusually high-Q antenna and
mixer coils compared to commercial ham sets.

Many hams would be using an antenna that's not good on 160 (when on
higher bands) and that provides an added measure of protection.

And finally, it's highly unlikely that even at worst all of these
channels would be in use near a particular QTH, so a tweak of the 2nd
oscillator and 1st IF transformers should get you a clear channel.

However, it might be well to use a general coverage receiver to check
this out before ordering parts or winding coils.

Walt
KJ4KV