[Heath] HW-16 additional questions

[Kenneth G. Gordon]

On 11 Mar 2014 at 12:26, Mark Johnson wrote:

> As for power out I usually get
> about 40 to 50 watts on 80 and 40 and about 30 on 15. 

Which brings up an important point: some time ago, there was a Hints and 
Kinks cure in QST for the lower power on 15 meters which was, apparently, 
common to most HW-16s, including my own.

In that Hints and Kinks it was suggested that the reason for lower output on 
15 meters was simply because the final tank coil had a bit too much 
inductance and the system was thereby could not be made to be truly 
resonant on 15 meters.

The clear indication of this is that the plate tuning capacitor has to be fully 
against the low-capacitance stop for maximum output, which varies, 
depending on the HW-16 from 20 to 30 watts output, whereas 50 watts 
output on 40 and 80 is the norm.

The suggested cure was to simply push the bottom few turns of the plate coil 
down and adjust them to be as far apart as possible, avoiding shorting the 
bottom turn against the bottom mounting bracket in the process. Increasing 
the spacing between the turns reduces the coil inductance a bit.

After doing this, it was suggested that realignment of the receiver should be 
done.

I followed these suggestions with my own HW-16s (I have three) and found 
those suggestions to be completely satisfactory.

Output on 15 (and receiver sensitivity) both improved and my HW-16s all 
output 50 watts on all three bands.

Since that time, I have discovered that when building the rig, it was very 
clearly shown in the manual that the lead from the TOP of the plate coil 
should be partially "wound around" the top of the coil in order to get it to the 
proper connection point on the bandswitch with minimal interference to other 
components.

Doing this, obviously, adds at least 1/2 turn to the total inductance of the 
plate coil, which would automatically change the L/C ratio which had been 
calculated by Heath engineers previously.

This would not materially effect either 80 or 40 meters, but would be 
significant at 15.

Furthermore, this 1/2 turn is NOT shorted out when the bandswitch is set to 
15 meters. Therefore it remains...to increase the inductance of the plate coil 
on 15 meters, thereby ruining true resonance.

YMMV.

Ken W7EKB