Re: Poor quality SRF59s - can they be aligned ?


Michael Slattery
 

On Fri, 28 Mar 2008 14:09:29 EDT, you wrote:

The alignment procedure usually gives a big boost in SRF-59
sensitivity, and should be considered by all owners to ensure maximum DX performance.
Greetings all from the city of Sheffield, Yorkshire, in the north
central part of England, UK!

So far I have had three examples of the SRF-59. All have the static
noise problem when tuning. All suffered the ferrite coil adjustment
being badly misaligned. As Gary says a big boost in overall
sensitivity and nulling is gained by alignment. Well worth doing.

The simplest way I've found to free the coil for alignment is to first
extricate the PCB from the case. For the protection of the components,
wrap some cardboard around the PCB leaving just the ferrite aerial and
the PCB area underneath it exposed. Then play some warm air from a
hair drier or carefully from a heat gun onto the exposed area of PCB
under the rod. Watch the condition of the wax noting when it has just
become molten at the point where it is in contact with the PCB. Try to
gently slide the coil side to side and when free simultaneously
withdraw the PCB from the warming airflow. Keep moving the coil from
side to side whilst the wax solidifies. Once the wax has solidified
the coil should remain free. It will look like there is a crack in the
wax between the coil and the PCB. Alignment can then commence.

Once alignment is complete, rewrap the PCB in the cardboard, reheat
the PCB under and around the ferrite aerial to remelt the wax. Tilt
the PCB so as to encourage the wax to bridge the coil and the PCB
until it appears fused as before.

I would encourage anyone to have ago at this. There is little to go
wrong as long as care is taken.

--
Michael G8PNX
wildbear@bigfoot.com

Join main@UltralightDX.groups.io to automatically receive all group messages.