[Collins] 30S-1

[jeremy-ca]

The 4CX1000A has a zero Ig  rating. As such it was too fragile for some 
applications and the failure rate was high. In addition the IMD was poor 
when run at close to its maximum ratings.

The 4CX1500B surprisingly has a lower Ip maximum. It has a new control grid 
with a 1W rating; it requires a different Eg than the 1000A for the same 
level of AB2 operation. Screen requirements are different also. Typical 
operation runs a EG2 of 225V vs 325 for the 1000A. IMD is substanially 
better and equals the best of the triodes.

Obviously it requires a change to both grid and screen voltages in order to 
take full benefit of the improved IMD.

Ive run both tubes on 2M and performed detailed IMD tests. The differences 
when each is setup properly is substantial and in the 15dB range.

I dont know the blower rating of the 30S1 but going from 1000 to 1500W 
dissapation requires a big jump from 18 cfm @ .23" drop to 34 cfm @ .60" 
drop. Thats a huge difference in order to keep the seal temperatures within 
rating. Its probably of no consequence on CW/SSB but RTTY and digital mode 
operators should be aware.

Carl
KM1H


----- Original Message ----- 
From: "Dr. Gerald N. Johnson" <geraldj at storm.weather.net>
To: <collins at mailman.qth.net>
Sent: Tuesday, September 11, 2007 2:34 PM
Subject: Re: [Collins] 30S-1


> On Tue, 2007-09-11 at 16:03 +0300, Baruch Zilbershatz wrote:
>> The 4cx1500 is designed for SSB you get better IMD and more power then 
>> the
>> regular 4cx1000a.
>>
>>
>>
>>
>>
>> Baruch Zilbershatz
>>
>> 4Z4-RB
>>
>> Ha-Shibolim 18 Nitzanay-Oz,
>>
>> Nitzanay-Oz 42836
>>
>> ISRAEL
>>
>>
>
> Both were designed for SSB or audio. There are no class C ratings for
> either in the data sheets because their grid current ratings are too low
> for class C. Both data sheets claim low distortion. The 1500 may claim
> better distortion from less grid electron impact on the control grid.
> -- 
> 73, Jerry, K0CQ, Technical Advisor to the CRA
> All content copyright Dr. Gerald N. Johnson, electrical engineer
>
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