I have seen your problem in the Softrock of a friend, it didn't select
the BPF for that band, either automatically or manually. The problem
was a bad optoisolator, it originally was ok but it became bad later, I
don't know why. So your problem is either the filter itself, but you say
that you tested the coils for continuity, or the optoisolator (very rare
that this kind of failure repeats) or one of the switches . Without a
scope you can check the output of the optos with a voltmeter while
exercising the filters in manual. If ok then you can probe the
corresponding pins in the switches. If the line that connects the opto
to the switch chips is always low maybe it is connected to ground by a
solder bridge, check with an ohmmeter with the power off. You can also
monitor the DC levels of the working filters, both on and off, this can
give us a clue.
73 de Ignacio, EB4APL
On 24/02/2013 1:11, jmshaffer_pa wrote:
> I have a Softrock that I bought second-hand from another user last year.
> It seems to hardly receive anything from 4 to 8 MHz, the bandpass filter
> #1 range. I'll get a few strong broadcast stations (unless they're
> images... I haven't taken time to verify the frequencies on all of them)
> but hardly ever any hams or utilities. In fact, in some parts of the
> range, the signal display is virtually flat. All other bands work fine.
> And, if I manually set the bandpass filter selection from #1 to #2
> (nominally 8-16 MHz), I get great, although sometimes image-plagued,
> reception from 4-8 also.
> I see comments here on the list about deafness being caused by failure
> to clean the enamel from the coil wire before soldering it in, so I
> pulled up the assembly instructions and schematics and tested for
> continuity through the filter #1 inductors. They're fine. I don't know
> what else to try, because I don't have a scope or a signal generator.
> So, is the 4-8 MHz filter just a particularly bad filter (which I can
> hardly believe would've been intentional, given the amount of activity
> on the 40m ham band), or do I have something else going on?