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On the first turn of L13, insert a twist. Leave 3" of free wire on the free end as the connection from L13
to the board is rather long, as shown below. Next epoxy this single coil turn all the way around the
tuning coil form and wait several hours for it to set. In order to wrap this coil, the first turn needs to be
firmly anchored in place, and the epoxy does that.
Figure 73. Wrap first turn on the PTO coil. Position ¾" back from front, twist single turn in place
Several hours later, after the epoxy has solidly dried, wind the next 104 turns tightly, with all turns
wound "shoulder to shoulder" as shown. On the last turn, tightly wrap the last ½" of the coil with
Make sure to keep the coil turns wrapped snuggly on the coil form
Teflon plumbing tape.
the entire time. A loose coil will drift badly.
105 turns is too many turns. However, the Teflon plumbing tape will allow the extra turns to be pulled
off the end of L13 in order to tune to PTO to the proper frequency. In this manner, we can avoid the use
of an expensive tuning capacitor to set the final receiver tuning range. Each complete turn removed
from the coil moves the PTO frequency by roughly 11 KHz of tuning range. Partial turns can be
removed at the end of the tuning process. Just keep in mind that placing the cover on the receiver will
move the frequency an additional 2 KHz (2 KHz higher on 20m, 2 KHz lower on 30m)
Figure 74. First turn is glued (epoxy) into place to make it easier to wrap the rest of the turns
When epoxy is used to anchor the first turn into place, double check to make sure it is spaced ¾" inches
from the front.
Norcal NC2030 v5
12-18-05
Page 64 of 128
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