12-10-2012, 10:50 AM
Hi again Joe, also forgot to say, the B40 series are thin on the ground compared to the R1155, if it's an auction job then you will almost certainly have to collect it one way or another they are not to massive they have a smaller footprint than say an AR88 but as you are probably aware, they are heavy at around 100lbs. I like the B40, quite reasonable to get at inside and perform very well, If doing a first time strip down of the tuning drive mech. either the dial drive or the capacitor drive or both then note everything down carefully, the full manual is a good one and is free somewhere on the web. Also note that the shaft on the tuning gang is ceramic and is a hard to find replacement item in the event of a f**k up in fact most dedicated B40 spares are in generall hard to come by.
Alignment (if needed) of the IF's is a bit more complicated than the norm due to the Xtal filter which I seem to remember is a two pole job in the B40, it's not beyond scope of the first timer though.
Ideally it should be done with a wobbulator/sweep generator and a suitable 'scope display, having said that I do not possess such instruments as yet but I have aligned many Xtal filters by ear or by using an analoge Avo meter connected across a suitable point, some comms sets are fitted with an "s" meter this can be used to align the xtal filter as well providing the rest of the receiver is up to spec and the signal level is kept low(ish) with these other methods it will not be theoretically perfect but it won't be far off once you have done a couple.
If going for a B40 series then I would recomend a later suffix one as they have an Osc Trim (Local Osc) control as a user control on the front panel and also they are rigged up for FSK reception, if no interest in FSK then you can adjust the FSK trimmers (which just shifts the BFO frequency) for upper or lower SSB corresponding to the settings of the function switch which can make things easier when switching the bands to tune in to the various SSB transmissions, most amature transmissions are LSB below 10 megs and USB above 10 megs, this general rule does not always follow though for aviation or military related or any other type of SSB transmissions.
Getting on to Shortwave reception opens up a whole new part of the hobby. Some of this you might know some you might not, whichever way good luck if you get one.
Lawrence.
Alignment (if needed) of the IF's is a bit more complicated than the norm due to the Xtal filter which I seem to remember is a two pole job in the B40, it's not beyond scope of the first timer though.
Ideally it should be done with a wobbulator/sweep generator and a suitable 'scope display, having said that I do not possess such instruments as yet but I have aligned many Xtal filters by ear or by using an analoge Avo meter connected across a suitable point, some comms sets are fitted with an "s" meter this can be used to align the xtal filter as well providing the rest of the receiver is up to spec and the signal level is kept low(ish) with these other methods it will not be theoretically perfect but it won't be far off once you have done a couple.
If going for a B40 series then I would recomend a later suffix one as they have an Osc Trim (Local Osc) control as a user control on the front panel and also they are rigged up for FSK reception, if no interest in FSK then you can adjust the FSK trimmers (which just shifts the BFO frequency) for upper or lower SSB corresponding to the settings of the function switch which can make things easier when switching the bands to tune in to the various SSB transmissions, most amature transmissions are LSB below 10 megs and USB above 10 megs, this general rule does not always follow though for aviation or military related or any other type of SSB transmissions.
Getting on to Shortwave reception opens up a whole new part of the hobby. Some of this you might know some you might not, whichever way good luck if you get one.
Lawrence.
