The AM Forum

I have always used a grid dipper.....However, I am at a friends shack helping convert a BA1K McMartian to 40, 75 and 160...He doesn't have a grid dipper...are there alternatives?   Thanks   Steve
UPDATE
trying the MFJ ant analyzer to check for impedance dips in the ham bands...steady Z readings on 160 and 75 Z varies by 30 ohms when sweeping 40...

do you have a signal generator and oscope or other means of showing rf level ?

I have always used a network analyzer because I've had one.  But the MFJ259 ought to work, again looking for what are generally sharp resonances.  Watch for a quick dip on the reactance meter.   It's important, though probably more so above 20 meters or so, to check the choke in the position where it will be located in the RF deck.  In some setups, the choke may be close enough to metal parts to have enough stray capacitance between the choke windings and the metal object.  That would move the resonance around from where it would appear on the bench.  Assuming you are using the original McMartin choke, you might consider removing turns, as you won't need as many on 160 and beyond as you would at the bottom of the AM band.  One hundred to 150 microhenries ought to work fairly well, and is less likely to pose problems on 40 meters.
73 de Norm W1ITT

large dips on the mfj only show up above 30 meters ...It looks like it might be OK

I've used a coax tee with a dummy load on one side and the choke in series with a grain of wheat bulb on the other. If the bulb doesn't light at 100 watts call it good.