[HBR] Coil "Q"

[Sandy and Kees Talen]

>From coils shields to the coils themselves........

Tried a few different coil forms and got the attached data.

The 1-1/4" amber plastic pill bottle looks good, is cheap, is 
available, but it's not sturdy and needs a connector attached. 
The PVC looks surprisingly good, is cheap, is readily available, 
is sturdy and needs a connector attached.

I wouldn't use paper/cardboard as a coil form and definitely
don't use fingernail polish to hold the turns in place. The 
silicone adhesive affects it some but it won't crack like
super glue. Haven't tried Duco cement.
 
All coils wound with #28 AWG magnet wire.

"Q" at 6 Mhz with all coils measuring 20.5uH (cap 35pf):
------------------------------------------------------------------------
Note #                               1       2      3      4      

1-1/4" Amphenol 5-pin    175    --    175    --
1-1/4" amber pill bottle    180    --    177  172
1-1/2" amber pill bottle    161  145     --     --
1-1/4" untreated paper/   152  130     --     --
          cardboard
1-1/8" PVC                      173    --    175    --

"Q" at 9.5Mhz with all coils measuring 8.4uH (cap 35pf):
-------------------------------------------------------------------------


1-1/4" amber pill bottle      --     --     187    --
1-1/8" PVC                        --     --     180    --

Notes:
1 - plain wiring, no adhesives to hold windings
2 - use clear fingernail polish to hold windings
     (strips didn't work, light coat across coil)
3 - use Elmer's Stix-All silicone to hold windings
     (4 strips across coil)     
4 - use Scotch black electrical tape to hold coil
     windings (1-1/2 turn)



73s  Kees K5BCQ