[AMRadio] B&W 5100

[Jim Wilhite]

The plain 5100 is a bit different.  While the iron is the same, the audio 
stages are a bit broader in the 5100.  Not a lot but enough that properly 
run will sound better than the B model.   The 5100 does not have the 
couplate but rather discreet components and uses .001 coupling caps between 
stages.

You can change them to .005 and change the cathode by pass cap on the 6AQ5 
to 25 uf.  Those are the mods that Moe, W5KD used in his and everyone raved 
about his audio using a EV 638.  The set doesn't need a lot because of the 
problems Dave pointed to.

The B model changed to couplates and restricted the bandwidth to comply with 
the narrower signal for SSB and the push by the ARRL for narrower 
bandwidths.  The cathode resistor in the B model was different in that 
cathode circuit as well.

Jim
W5JO



>> I have a 5100B that is unmodified....still has the couplate and no mods
>> other than the usual cap replacement.
>> The rig has barely 100W output so anything you do to add any bass or 
>> reduce
>> the treble will make it even harder to make a contact.
>>
>
> Good point, but if the set isn't capable of passing the frequencies it
> won't matter anyhow. I don't have a schematic for the 5100, but a lot of
> those sets limited the audio passed through as a result of coupling cap
> values and so on. If that's the case with the 5100, all the processing in
> the world won't help until the restrictive components are changed to
> different values.
>
>
>> I use a standard un-amplified D-104 and get good audio reports.
>> The rig is being used as it was designed and the audio is effective at 
>> this
>> power level.
>
>
> That would be my choice as well, a good ol' crystal D-104 mated up with a
> proper input resistor (5 Meg or more in most cases) usually does the best
> job sans processing. They sound good and have the necessary punch for a 
> low
> powered rig. You can still find them easily at hamfests for $20-$50, 
> though
> making sure you get a good cartridge is the tricky part.