[Amps] Old Moto RF Decks

[John Kinney]

Hi Carl,

You are correct.  I saw very poor IMDs on the two tube version at anything over about 400 Watts.  I friend of mine helped me build a filter, 5 poles as I recall, for use on the output.  It brought the 2nd and 3rd harmonics down quite nicely, using two tone 1 kHz spacing.  We used an Anritsu Spectrum Analyzer for monitoring into a 2KW dummy load and the 2nd and 3rd harmonics were down about 50 and 70 db as I recall.

It was a lot of fun playing with those old amps.

Thanks,

John Kinney
RF Solutions Team
Freescale Semiconductor
Tempe, Arizona
(480) 413-4290
KA7CVJ


-----Original Message-----
From: Carl [mailto:km1h at jeremy.qozzy.com] 
Sent: Monday, December 01, 2014 1:43 PM
To: Kinney John-R17512; amps at contesting.com
Subject: Re: [Amps] Old Moto RF Decks

SSB IMD goes up rapidly above 300W per tube even with simplistic screen regulation. Be a good neighbor on the bands with those rather aged and obsolete designs (1947) that predate widespread SSB use.

Collins rated their 1960 AN/URC-32 at 500W with a pair of lower IMD 4CX250R's at 2000V while Eimac rated them to 2500V with poor IMD specs. 
Those transceivers, at 6' tall, ran fine without clobbering other close channel USN users.

Carl
KM1H