[Elecraft] RE: Does anyone miss passband tuning, audio notch on K2?

[Ron D'Eau Claire]

Not at all Rod. 

A tunable BFO allowed one to put a signal in the center of a tight
filter, and then change the audio frequency of the note without changing
the "tuning" of the signal in the i-f bandpass at all! 

It's the same thing the K2 does for us when go into St P and change the
"sidetone" frequency. 

My 1940's vintage HRO-5 had an i-f filter that could be cranked down to
a couple of hundred Hz (well, back then it was cp/s) AND it provided a
tunable notch. 

What it did NOT offer were the wide bandwidths with steep skirts as we
expect today for SSB. But, back then "phone" was AM with each signal
occupying 6 kHz of the band! 

I could go on with a list of other things the old receiver did not
offer, from stability, dynamic range, image rejection etc. etc., etc.,
but true narrow bandwidth for CW is nothing new,  A lot of us did with
less, using our first regenerative receiver or a simple, cheap superhet,
but the good Ham stations from the 1930's onward offered the tightest CW
selectivity one could use. 

I do miss the ability to grab a front panel knob and change the tone of
the CW I'm copying (without changing it's position in the passband) at
will. Indeed, my "second" rx has a BFO knob on the front panel. But
that's a superhet that I designed myself, and adding a tunable BFO made
as much sense as adding a tuning dial. But it's a receiver, not a
transceiver, so it doesn't have all the functional issues of
automatically putting a transmit signal zero beat on the received signal
that are handled by the K2.

My age shows every time I look in the mirror!, Hi!

Ron AC7AC
K2 # 1289



I believe the "tunable VFO" was an accomodation to the wider passbands
in the rigs of yester-year. If I recall 1, 1.5 or even 2kHz BW were
typical in the "old days". So, BFO tuning helped to mitigate things as
you describe. All things being equal, I'll take the tight precision of
today's modern radio-electronics technology. TUVM :-) It won't be long
before IF-DSP and SDR will be par for the course in most every rig.

73, Rod N0RC