[AMRadio] Re: AM Transmitter Advice??


George KB2Z Thermionic_Emission at earthlink.net
Fri Feb 17 07:06:07 EST 2006


Reverse biasing the galena crystal was a stroke of genius. 100% negative 
side modulation with no need for clipping on the pos. side. Cleanest 
class C sine wave ever. Brilliant.

Brian Carling wrote:
> I think that was the APRIL issue of Tube Collector magazine.
> The heck of it is, he used a galena crystal as a modulation 
> transformer!
>
> On 16 Feb 2006 at 20:42, John Coleman ARS WA5BXO wrote:
>
>   
>> OK BOB!
>> 	You got my attention. Explain more.  I hope I'm not a sucker
>> here.  I have seen and extremely low mu amplifier circuit (common
>> cathode) made by reverse biasing the plate of a triode and forward
>> biasing the grid where output is taken from the grid and input is on the
>> plate.  So I know that weird stuff does exist.
>>
>> John, WA5BXO
>>  
>>
>> -----Original Message-----
>> From: amradio-bounces at mailman.qth.net
>> [mailto:amradio-bounces at mailman.qth.net] On Behalf Of Bob Deuel
>> Sent: Thursday, February 16, 2006 6:05 PM
>> To: 'Discussion of AM Radio'
>> Subject: [AMRadio] Re: AM Transmitter Advice??
>>
>> Hello Larry and all:
>>
>> Larry's tongue in cheek comment employing 866's as a linear amplifier
>> tube
>> prompted me to contribute the following: Certain full-wave rectifiers
>> can be
>> configured to amplify or oscillate. I have built audio, Hartley and
>> Simpson
>> oscillators using only 6AX5GT's full-wave rectifiers as the sole active
>> device. These were displayed at 2004 Mid-Atlantic Antique Radio Club
>> Meet
>> and actually won a Blue Ribbon.
>> Late last year I built an AM transmitter consisting of a Hartley
>> oscillator
>> modulated by an AM modulator using only 6AX5GT full-wave rectifier tubes
>> as
>> the active devices. No solid-state magic, just simple full-wave
>> rectifiers.
>> The basic concept is that of the Heintz and Kaufman gridless Gammatron
>> circuits. The transmitter was set up for the broadcast band and works
>> fine.
>> It has been publicly demonstrated a couple times now and a write up
>> including the circuit was published in the February, 2006 issue of the
>> "Tube
>> Collector" magazine which is the bi-monthly magazine published by the
>> Tube
>> Collectors Association, Inc. It is fun to make full-wave rectifiers do
>> more
>> than just rectify.
>>
>> Bob, K2GLO   
>>
>> -----Original Message-----
>> From: amradio-bounces at mailman.qth.net
>> [mailto:amradio-bounces at mailman.qth.net] On Behalf Of ne1s
>> Sent: Thursday, February 16, 2006 10:36 AM
>> To: Discussion of AM Radio
>> Subject: [AMRadio] Re: AM Transmitter Advice??
>>
>> Donald Chester writes: 
>>
>>     
>>>> Assuming one is going to build a linear, and so putting aside other 
>>>> issues
>>>> such as linear vs plate modulation, why do you think it makes a 
>>>> difference
>>>> what tube is used? Are you referring to running a linear at greater
>>>>         
>> than
>>     
>>>> legal limit?.
>>>>         
>>> Well, go ahead and try building a legal limit linear that runs a pair
>>>       
>> of 
>>     
>>> 807's in the final. 
>>>
>>>       
>> Yeah, or a pair of 866As.... 
>>
>> Sorry (the devil made me do it). 
>>
>> 73,
>>  -Larry/NE1S
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>>
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>>     
>
>
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>   
Reverse biasing the galena was a stroke of genius



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