[Boatanchors] [Hallicrafters] Fluke 6060a/an or HP 8640b ?

[Bob, W5UQ]

Jim,
        I'll have to get into the unit again to verify this, however, I 
could have sworn that the freq bands get off when turning the knob.  It 
seems to me that the "shark type gear" is used at other places too... I 
thought I saw that when I was in it months ago... not really sure.
Bob

Jim Wiley wrote:
> Michael et al -
>
>
> At least in my 8640B, the symptoms of broken gears primarily show up 
> when using/generating FM signals.  The way the 8640B works, it has to 
> increase the modulation/deviation of the oscillator to maintain the 
> correct output signal as the frequency is lowered from the "basic" range 
> of 256-512 MHz.  If the gears are broken, the front panel modulation 
> meter will indicate (using the 128-256 range as an example) 5 kHz 
> deviation but the generator is only actually producing 2.5 kHz 
> deviation.  The modulation of the basic oscillator must be increased by 
> a factor of 2 each time the output frequency range is halved.
>
>
> The purpose of the gears is to operate an internal control that boosts 
> or reduces the deviation of the main oscillator in step with the 
> band-switch so that the output signal is what the user wants.  There may 
> be other uses as well, but that is certainly one of them.
>
>
> A generator with a broken gear set will still work fine for CW and 
> possibly AM signals, bit not for FM signals.  The carrier frequency and 
> output level attenuator will be fine, and sometimes that's all a person 
> needs, but to perform alignments of FM receivers, and for certain other 
> uses, such as using the 8640B for slow to medium frequency sweeps, as 
> for example when sweeping an IF stage, having the FM section working 
> correctly is necessary. 
>
>
> BTW, that last technique works well when the 8640B modulator is driven 
> from a function generator with a sawtooth wave, and synchronized to a 
> scope and RF detector for an output display.  The 8640B modulator stage 
> will respond from several hundred kHz down to DC.  The combination  
> makes an excellent sweep generator for aligning IF stages, clear down to 
> 500 kHz or so (some 8640B's will under-range to 455 kHz, some will not.  
> To do the latter properly, one should have the low-frequency 
> converter.   The converter is HP part number 11255 or something close to 
> that, and gives you the full performance of the 8540B down to 20 kHz or so.
>
>
> And, oddly enough, visual inspection probably won't be too revealing.   
> The action of the gear set is complex, and not easily determined by 
> eye.  I stared at mine for some time and still couldn't figure out what 
> was wrong, but it sure shows up when using the unit.  To see the gears, 
> which are behind the front panel, you need to remove the bottom covers.  
> The gears are small white plastic gear sets that are clustered around 
> the band-switch control shaft. 
>
>
> - Jim, KL7CC
>
>
> Michael OBrien wrote:
>   
>> Hi All
>> How can you tell if your gears are broken while using it and how far do you have to open it up to see it
>>
>> Mike
>>
>>   
>>
>>   
>>     
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