[TowerTalk] ICE 419B schematic, component values and replacement part numbers

[Jim Brown]

On 1/26/2020 5:35 PM, w5wz at w5wz.com wrote:
> The 15 meter section of one of my ICE 419B units failed during 2020 
> January NAQP SSB

Running barefoot into an antenna with SWR is a common cause of failures 
in low power BPFs. Don't know what your situation is/was, but I've had 
this happen to me years ago.

Some other crucial info for finishing the repairs -- that filter must be 
re-aligned using suitable test equipment; available adjustments are to 
squeeze or expand the coils in the 15M filter. The cover must be in 
place when the measurements are made, removed to tweak, replaced to 
measure, and so on. Especially with the construction of the ICE 419, 
that isn't easy. The best test equipment is a Vector Network Analyzer 
with software that can simultaneously display SWR, loss in the passband, 
and filter skirts. I use the VNWA3EC, designed by DG8SAQ and sold by 
hams in the UK. Without that realignment, the filter won't work very 
well and is likely to blow again.

The quality of these caps is also critical. They must have very low 
equivalent series resistance.

73, Jim K9YC