In a message dated
6/9/02 7:02:29 PM GMT Daylight Time, [email protected] writes:
Re: Decca
Using the original coils the inductance when measured in the
case and out of the case varies by several Uh and therefore difficult to
resonate/align properly
Not really.
The coils have about 3 turns at the top of the
former that are not fixed other than with a tywrap.
These turns can be
fully or partially wound in-phase or out of phase in order to precisely
resonate the tank circuits where you need them.
Only applicable to the A model on 127 khz and even then is not the best
approach for optimum alignment on 137 khz. The methods that I recommend in my
previous message will give the best results with a mimimum of trouble, and by
adjusting the core the resonant frequency is easily changed to cover the whole
band, any frequency between 135.7 - 137.8 khz.
Using the ferrite core method just select the appropriate tap to resonate
on the desired frequency.
Adjust each of the 3 coils.
All models except A need turns removing from the coils for optimum LC
using the BCB capacitor boards on 137 khz. Capacitor boards BCA need
modification as well as the coils for 137 khz.
Others in the UK have published information on their WEB
sites about Decca mods, so take your pick.
G3KEV
73
David G0MRF
