[600MRG] A 630 meter transmitter

[Eric NO3M]

What about as an ECO?  IIRC, the fundamental and second harmonic output 
are nearly the same, but are those at the same level as the fundamental 
output of a xtal oscillator with the same tube?  The original post 
mentioned not using a crystal, so it's either assumed the first tube 
stage will be driven by an outboard VFO or it will be a self-contained 
rig and the first stage frequency agile.

I prefer to run an ECO with an untuned plate and following Class A 
buffer, grid at 1/2 freq.  It made a huge difference in my 814 rack 
transmitter.

Re: 0.6W to excite 2x 807.... should be more than that if grid losses 
are accounted for.

73 Eric

On 01/28/2018 08:15 PM, Kenneth G. Gordon wrote:
> On 28 Jan 2018 at 19:55, Steve WD8DAS via 600MRG wrote:
>
>> Eric wrote:
>>      If going to parallel 807s (or 1625s), a 6AG7 oscillator (xtal or ECO)
>>      probably won't have enough output to fully excite the pair.
>>
>> I think it can, if operating on the fundamental.
> Of course it can: parallel 807s require 0.6 watts drive for 120 watts output, and a 6AG7
> outputs way more than that when operating at the fundamental..
>
> Here is a transmitter using a single 807, driven by a 12BY7 (which is very much like a 9-pin
> 6AG7).
>
> http://www.w7ekb.com/glowbugs/projects/inexpensive75wattxmitter.pdf
>
> There is even enough drive (barely) at 10 meters with this setup when the 12BY7 is
> quadruppling in one stage.
>
> Or how about this one, operating at less than 1/2 the full plate voltage for the 807/6BG6s?
>
> http://www.w7ekb.com/glowbugs/projects/65W%20at%20Low%20Cost.pdf
>
> Ken W7EKB
>
>