[AMPS] 5894's in amateur applications.

[nospam4me@juno.com]

Hi Bill and Co...

:From: Bill Aycock <baycock@HIWAAY.NET>
:..I have acquired parts of a commercial mobile tube rig
:.. The final is marked "Amperex", and is numbered 5894B

The 5894 and similar numbered tube were very common 
in the Two-Way Communications Radios through the 60's 
and early 70's.  The good old Motorola Research Line 
("Motrac - Sensicon Series"), RCA ("Really Crappy Audio") 
Radio Carphone and the General Electric Master Progress 
Line ("Master Pro")used them as finals for most of their 
VHF Hi-Band Radios. In both mobile and fixed applications. 

The 5894 is considered a big brother or upgraded version 
of the 829b tube and they use similar sockets. The 5894 is 
almost a third larger and has "upgraded ratings." There 
was and article in a past Amateur Publication where 
someone mounted a transmitter strip in a box with fixed 
power supply, using only the separated final section. 
I have a copy of it in my files somewhere. 

Here's the meat and potatoes... 
I've converted a number of these old strips down to the 2 
meter band. You will have to add capacitance to the final 
section, it's very dependant on the "band-split" (section of 
the VHF band where the strip was built for operation by 
the mfgr), how much additional work you'll have to do. I've 
even hack-saw'd off the final section to make smaller box 
amplifiers. 

5894 at "full tilt" will put out 90 watts plus, but you'll burn it 
up quickly with long key downs.  I used the FM IMTS 
Telephone continuos duty values and obtained 35-45 watts 
all day, every day for many years in my GE EP-38 chassis 
Master Pro FM Repeaters. Prudent operation has a fan 
blowing air past the tube in operation. The VHF Master 
Pro transmitter strip actually mounted the tube in a Heat 
Sink final assembly. The Motorhead version was air cooled...  

Older Handbooks and the FM and Repeater for the Radio 
Amateur contain amplifier circuits using this tube and the 
829b.  I even have an 829b amplifier in the back room. 
What a whooping 35 watts on 2 meters... 

cheers
skipp

http://sonic.ucdavis.edu
http://pilot.ucdavis.edu
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