>Thank you,
ur welcome, Dan.
>
>The exciter is a Heathkit 5400. In the last reading below it is driving
>the amp with about 30 watts. If I increase the input drive power from
>that point the grid current rises very rapidly and the output wattage
>flattens. Due to the cautions about grid current I have stopped there.
>(At that point plate HV has dropped to about 2KV) Is it feasible that if
>the amp were incrementally tuned it would return to a more linear
>relationship??
The preferable way to tune an amp is with max drive, with the amp Tune
and Load adjusted alternately for max out. Tuning a 220 with high speed
dits is safest.
>
>btw - ZSAC is about 100 ma on the CW/TUNE tap and about 150 on the SSB tap.
>
>Dan
>
>R. Measures wrote:
>
>>** Thanks. These grid-I figures seem normal to me. However, the ZSAC
>>(zero signal anode current) seems a bit low. With the reduced anode
>>supply V on the CW tap, grid current is higher because the anode is less
>>attractive to electrons - so more of 'em go to the grid.
>>- To fully drive a pair of 3-500Zs, it takes well over 100w.
>>
>>
>>
>>>Thanks,
>>>
>>>The following data was collected from an antenna with an SWR of about 1.5.
>>>
>>>Plate ma Grid ma
>>>100 0
>>>120 10
>>>140 20
>>>160 30
>>>180 40
>>>200 50
>>>300 100
>>>600 150
>>>
>>>These were obtained by carefully increasing the drive and incrementally
>>>tuning first load and then tune. These appear to be good results.
>>>Attempts to tune directly have to be approached very slowly and
>>>carefully. Is it possible the high grid current readings are a result of
>>>poor tuning skill on my part??
>>>
>>>Dan
>>>
>>>
>>>R. Measures wrote:
>>>
>>>
>>>
>>>>With 700 - 800mA key-down on the CW tap, what is the grid-I? Tnx.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>>All,
>>>>>
>>>>>I have an sb-220 with non-uniform grid current. With low to medium drive
>>>>>grid current is linear (or apparently close to it) with plate current
>>>>>(minus about 100 ma base) and output power. However if input drive
>>>>>exceeds the medium level of 25 to 30 watts grid current starts to hockey
>>>>>stick "high". It is not a digital switch; but a very steep response.
>>>>>
>>>>>The components in the bias and grid meter side of the circuit have been
>>>>>checked in circuit. The grid bias coil has been replaced with an 1/8
>>>>>watt 33 Ohm resister.
>>>>>
>>>>>Thanks,
>>>>>Dan
>>>>>
>>>>>
>>>>>
>>>>>_______________________________________________
>>>>>Amps mailing list
>>>>>Amps@contesting.com
>>>>>http://lists.contesting.com/mailman/listinfo/amps
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>>
>>
>>
>>
>
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