[Hammarlund] Dumb tuning question

[SP600historian@aol.com]

In a message dated 9/15/02 3:08:00 PM, Delibert3A@aol.com writes:

<< Here's a trick that many of us used in those good (bad?) old days when no 
one 
had digital tuning and only those who could afford a Collins 51j-3 or -4 
really knew what frequency they were tuned to.  When I first read about this 
method in 1961, it opened a whole new world on my Lafayette HE-30.

You need a piece of graph paper.  Along the left edge draw a vertical axis, 
label it "logging scale" and label it with numbers 0, 10, 20, etc. up to 100. 
 Along the lower edge draw a horizontal axis and label it "frequency."  To 
the right-hand side of that axis, mark one of the points with a frequency at 
the upper end of the band you're interested in, say 13800.  About 2 inches to 
the left of that, mark the axis 13700; two inches to the left of that, 13600, 
etc.  

The bandspread tuning dial should be set to the high end, so the logging 
scale along the bottom reads "100."  Using the crystal calibrator, tune the 
main tuning dial to 13800.  (Finding this might be a trick.  Maybe find the 
lower edge of the CW portion of the 20-meter ham band (14000) and count down 
2 calibration points.)  On the graph paper, mark the point corresponding to 
100 on the vertical axis and 13800 on the horizontal axis.  

Now tune the bandspread down until you come to the next calibration point, 
which should be 13700.  (Some HQ-180s have 200 kHz crystals in their crystal 
calibrators.  In that case, of course, the next point would be 13600.)  Note 
where the pointer reads on the 0-100 logging scale.  Mark the point on the 
graph paper that corresponds to this number on the logging scale and 13700 on 
the frequency scale.  Now tune the bandspread down to 13600 and so on.  

Draw a smooth line connecting the points.  You now have a graph that allows 
you to translate any point on the logging scale into a frequency.  You just 
have to make sure that when you start, the bandspread is set at 100 and the 
main tuning is set to 13800.  This method is not exact, because the tuning is 
not precisely linear.  But it's very close, and if you recognize some 
stations as you tune across the dial and you know their frequencies, that 
helps you deal with the variations from linear. 

Many bands require more than one full turn of the bandspread dial to travel 
the whole band.  So for them, you need two graphs, one starting at the top of 
the band, another one starting somewhere in the middle, where the first graph 
leaves off.  

Hope this helps.  

Art Delibert, KB3FJO
>>

Hi Art and group,

Yep, this is how it was done. Unfortunately, today the "need it now" 
generation will not have the patience to do this. It also meaant learning the 
bands and "knowing" what broadcaster was transmitting "where".





Les