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[Amps] {Collins} 30S-1

To: "Amp Reflector" <>
Subject: [Amps] {Collins} 30S-1
From: "kingwood" <>
Date: Tue, 20 Oct 2009 17:07:01 -0500
List-post: <">>
Greetings to all,

        There is some misinformation  being passed out here about these 
tubes.  There are two common 4CX1,500 tube types, the "A", and the "B".  The 
"A" tube has a 25 watt grid dissipation rating but will not work in the 
30S-1 without changing the tube socket.  The "B" tube has a 1 (one) watt 
grid dissipation and will directly replace a 4CX1,000 in a 30S-1 amp.  As I 
said in an earlier post, this is a X 10 increase in grid dissipation over a 
        It is important to know, and understand, that the band switch in the 
30S-1 was never intended to see more than about 600 watts of RF.  This amp 
was designed at a point in time when US Amateurs were only allowed to run 
1,000 watts AVERAGE INPUT power, not OUTPUT.  This band switch is made on a 
thin sheet of G10 fiberglass with contact points riveted on.  My point is, 
be careful how you handle this switch, both power applied and switching.  I 
had to pay $500 for the last one I changed out for an RTTY operator.  In my 
opinion, the 30S-1 should never be operated on any continuous mode.  High 
speed CW is also very hard on it.

        Despite the other numerous faults with this amp, it is still around 
and quite a topic of conversation.  Ask yourself why has it not increased in 
value comparable to other similar amps.  If you ever had to maintain a 
"fleet" of these amps, as with the MARS program, you will understand why.

        I have a 30S-1 with grid drop-out mod, fused step-start,  and 
4CX-1,500 with increased screen voltage.  With these mods, it runs reliably 
in SSB but I still cringe every time I turn it on -- so many more bad 
things, than good things,  can happen every time it is turned on.

73 de Lon, K5JV

1110 Golden Bear Ln.
Kingwood, TX 77339

281-358-4234 FAX
281-795-1335 CELL 

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