Construction of the MKARS80 Transceiver continues with the population of bag #3.  This bag contained most of the toroids and bobbins to wind.  One of the challenges, from the colonies side of the Atlantic, is the lack of an intuitive feel for the metric system.  I was thinking that 50mm = 0.5 cm.  But it turns out that it is 5 cm. I guess if I would have thought about it, I could have compared it to electronics.  1 milliamp = 0.001 amp. So 1 millimeter = 0.001 meter, whereas 1 centimeter = 0.01 meter.  So now I get it.  Anyway, even with trimming the leads 10 times too short on the first transformer, it was still long enough to reach.

Note that it takes a really hot soldering iron to burn the insulation off of the enameled wire.  I used about 780F degrees when soldering in the transformers.  For the rest of the components, I used about 750F degrees.

Transformer T4, with leads cut way short.

After discovering the ills of my ways in the metric system, I got the rest of the lengths correct.

T5 with leads at 50mm, as specified

I read the inductance of individual windings on all of the transformers and coils with my AADE meter:

  • T4, T5, T6 = 39.47 uh
  • T1, T3 = 42 uh
  • T2 = 22 uh
  • L3 = 7 uh
  • L1, L4 = 2.76 uh
  • L2 = 2.886 uh
  • L5 = 4.94 uh

 

AADE Meter reading inductance of transformer winding

Before winding T2, I deburred the edges of the binocular core.  This is to reduce the chance that the sharp edges would scrape the insulation off of the wire inside, as I was winding it.  It is a really close fit, and so this was a concern.

Deburring binocular core

Using the AADE meter is simple.  Just turn it on, short out the leads to zero it out, then connect the leads across the coil and read the inductance.

Coil L1 hooked to AADE meter

The VFO coil had 40 turns.  It may have to be expanded to increase the tuning range to cover the whole US band.  The UK has less allocations on 80 meters than the US.

L5 VFO coil

So here is the board with bag 3 components installed…

Bag 3 components installed