1-02-26 04.50, skrev measures på 2@vc.net följande:
>
>>
>> measures wrote:
>>
>>> I ran a pair of paralled 4cx250Rs on 2m SSB. The tank was 1/4 wave.
>>> With a screen current of c. 5mA (@400screen-v), the linearity was good.
>>> Output was c.900w PEP on SSB. 10w drove it.
>>>
>>> cheers
>>>
>>> - Rich..., 805.386.3734, www.vcnet.com/measures.
>>
>> I think in these arguments (anf it seems to have developed into that),
>> it is essential to define what 'good' is.
>
> Good means no splatter complaints from nearby staions.
>
>> It's a bit pointless saying
>> 900 W at good linearity, without defining what 'good' is. Does 'good'
>> mean that it did not sound distorted at the other end, or that the 3rd
>> order products were more than x dB down ?
>>
> none of the above
>> Without 'good' being defined, there is little point is arguing about
>> whether a single 4CX250B can produce 250, 300, 450 or even 1 kW. I took
>> a data sheet figure of 300 W, but clearly there is some tradoffs between
>> power/linearity/tube life/voiding tube warrenty/and a whole host of
>> other things.
>>
>> --
>> Dr. David Kirkby Ph.D,
>> email: drkirkby@ntlworld.com
>> former email address: davek@medphys.ucl.ac.uk
>> web page: http://www.david-kirkby.co.uk
>> Amateur radio callsign: G8WRB
>>
>> --
>> FAQ on WWW: http://www.contesting.com/FAQ/amps
>> Submissions: amps@contesting.com
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>> Problems: owner-amps@contesting.com
>>
>>
>
>
> - Rich..., 805.386.3734, www.vcnet.com/measures.
> end
>
>
> --
> FAQ on WWW: http://www.contesting.com/FAQ/amps
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>
>
It is about time to try to modify the 2 meter K2RIW to use, if possible, the
4CX400. If my memory is right, was there not already an article on using the
8930 = same tube as the 4CX400?
Come over here to Scandinavia when we have our monthly tuesday 2 meter
contest. Very few guys know nowadays anything at all about linearity and
wide splattering signals are accepted. There has even been guys using FM
transistor amps in SSB!!!
Years ago when I had a super QTH in southern Stockholm high up overlooking
Stockholm, I had to give up 2 meter contesting because the wide signals. The
worst thing was, that the offending stations did not go QRT after receiving
a polite complain but just continued calling. Even when I told them I
listened with an attenuator in series with the receiving ant to bring down
the signal to a S9 level to avoid receiving overloading. And came back in
the next tuesday contest with the same signal quality!
Sorry to say we must accept this situation to some degree as we can not
demand hams should have the same knowledge as the commercials and use
expensive spectrum analyzers. But a guy that is wide as a barn door even
when beeing only S9 and receives a lot of complains from hams who know how
to check signals. He HAS to do something. Why? Because it reflects back to
his own QRM situation when bad signals are beeing accepted as something
normal.
I would like to try the new TS 2000 on 2 meters with reduced power to 40 -50
watts to drive a 8877. Wonder what the linearity of the 2000 would look like
in 50 watts out and what about the relation peak power out to noise
sidebands when reducing power??
Prosit de Hans SM5KI
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