[Elecraft] K3 Low Pass Question

[Don Wilhelm]

Jim,

One reason not to use an external LPF is that many (most) of them have a 
cutoff frequency above 30 MHz, and below 50 MHz - and the K3 covers 50 MHz.

IIRC, Drake had one LPF that had a cutoff above 52 MHz (but the 6 meter 
band extends to 54 MHz).  I am looking at a Drake TV-3300-LP right now 
and it has a minimum attenuation of 80 dB above 41 MHz.

Most modern transceivers do not need external LPFs because they must 
comply with more stringent FCC spurious emission regulations than were 
in effect when many transmitters had a LPF hanging off the back for TVI 
prevention.

So, you can use it if you want, it will not hurt anything at HF, but 
unless it is one with a cutoff frequency above 54 MHz, you will lose all 
or part of the 6 meter coverage.

73,
Don W3FPR

Jim / W6JHB wrote:
> Just wondering if many K3 owners have a low pass filter in their coax line?
> I'm starting to assemble my station in a rental apartment and have a couple
> commercial low pass units lying in the parts box. Worth the extra (small)
> effort to put one in the transmission line? In my case, no additional $$
> cost, but it would add another pair of PL259's and a short length of cable
> to the configuration.
>
> Jim / W6JHB
>