[Johnson] Ranger keyer problem

[Mahlon Haunschild]

Phil,

Stock Rangers burn through 1614s because they aren't biased to cut off 
when not transmitting.  In any case, the 1614 is underrated for the 
Ranger plate voltage, a problem Johnson corrected by going to 7027As in 
the Ranger II (but good luck finding any of those).

Re-wiring the modulator to use EL34s is a good idea, but if I were you 
I'd try a set of Svetlana 6L6GCs first.  No re-wiring required because 
they both use the same base, but you'll want to move the tap on R35 to 
set the screen voltage to 400 volts.

Johnson probably would have used 6L6GCs from the get go, but they didn't 
exist back in the 1950s when the Ranger was designed.  But I still don't 
understand why they used the 1614 instead of the Joe Schmoe 6L6.  There 
isn't that much differnece in ratings between the tubes.

regards,

Mahlon - K4OQ

> Message: 1
> Date: Thu, 23 Oct 2003 11:32:58 -0400
> To: "Philip Atchley" <beaconeer@elite.net>, <Johnson@mailman.qth.net>
> From: Roy Morgan <roy.morgan@nist.gov>
> Subject: Re: [Johnson] Ranger keyer problem
> 
> At 11:06 PM 10/22/03 +0000, you wrote:
> 
> 
>>Incidentally, the two 1614 modulators test quite weak and with a "life" test
>>that drops.
> 
> 
> Phil,
> 
> These 1614's are a problem.. they are expensive to buy if you don't have 
> any (AES price is $30).  One possible substitute is the EL-34/6CA7 tube 
> being currently manufactured at prices of about $12 each.  The guitar guys 
> and gals use lots of them.  There are two considerations:
> 
> 1) Filament current. I just don't know if the EL-34 takes more filament 
> current. It may.
> 
> 2) Slightly different pinout.. the EL-34 *may* have a separate connection 
> for the screen on pin 6 (I think it does).  You'd need to clear any 
> connections on that pin being used as a tie point, and wire the pin to the 
> right place (cathode, I assume).
> 
> The current manufactured Tesla EL-34's are extremely rugged and I'd expect 
> them to perform very well in the Ranger.  I do plan to look into this idea 
> when I restore the Ranger I have here.  My Ranger has a kaput modulation 
> transformer and burned tube sockets. It will get a replacement transformer 
> I found, and ceramic sockets. This will let me make substitutions for the 
> tubes as needed.
> 
> I'd be glad to hear any ideas or more facts you may have on this.
> 
> Roy
> 
> 
> - Roy Morgan, K1LKY since 1959 - Keep 'em Glowing!
> 7130 Panorama Drive, Derwood MD 20855
> Home: 301-330-8828 Work: Voice: 301-975-3254,  Fax: 301-948-6213
> roy.morgan@nist.gov --