[AMRadio] Using an old Collins amp for AM


Paul Baldock paul at paulbaldock.com
Mon Jan 12 20:42:21 EST 2015


It's definitely worth the effort, 3dB is very significant for a 
marginal signal. However with your 30S1 you should be able to easily 
get 250W carrier and 1000W PEP which is 5.5dB more than your 70W. If 
you have modified your 30S1 for higher screen voltage, then you can 
get 1500W PEP and 375W carrier which is legal limit in the USA.

You will only need 30W or so of  carrier drive for, so for best 
modulation characteristics you should put an attenuator between the 
the driver rig and the 30S1 and then tune the driver for 70W (or 100W 
if that really is the spec).

Don't forge to tune the linear for maximum PEP and NOT for maximum 
carrier. The carrier level should be 25% of the PEP.

- Paul   KW7Y


At 05:10 PM 1/12/2015, you wrote:
>Raising the carrier from 70W to 150W means about gaining 1/2 of an S-point
>on the receiving end. 1 S-point is 6 dB increase in power, which is
>quadrupling it, as if you increased from 70 to 280 W carrier. Doubling the
>power is 3 dB, which is a half S-point.
>It's not worth the effort.
>
>73, Meir WF2U
>Landrum, SC
>
>-----Original Message-----
>From: AMRadio [mailto:amradio-bounces at mailman.qth.net] On Behalf Of FRANK
>HUGHES hughes
>Sent: Monday, January 12, 2015 7:10 PM
>To: amradio at mailman.qth.net
>Subject: [AMRadio] Using an old Collins amp for AM
>
>Hi,
>I would like to be able to participate in some of the AM nets.
>My 32V-2 only makes 70 watts of carrier. (low voltage selected)
>I have a good condition Collins 30S-1 that I normally use for SSB.
>If the power is kept down to about 150 watts of carrier, could I drive the
>amp w/ the 32V-2?
>
>
>My first homebrew amp is under construction, but until it is ready, I am
>hoping to find a temporary
>solution.
>73
>Frank
>KJ4OLL
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