[Boatanchors] Which one tube TX ?

[Geoff]

If you want to revert to the 50's an AC/DC TX using a 117M7/L7GT, 117N7GT, 
117P7GT can give you 2 to 5W out with the rectifier built in and work with 
any crystal. Just use common sense safety.

A 12BY7, 6GK6 and a few other 9 pin types will do more but requiires 200V+ 
to attain it.

Carl
KM1H


----- Original Message ----- 
From: "Bill Cromwell" <wrcromwell at gmail.com>
To: "Doug Forbes" <dougforbes at dslextreme.com>
Cc: <boatanchors at mailman.qth.net>
Sent: Saturday, April 28, 2012 11:04 AM
Subject: Re: [Boatanchors] Which one tube TX ?


> On Sat, 2012-04-28 at 07:44 -0700, Doug Forbes wrote:
>> I am building a one-tube transmitter and am concerned over the crystal
>> current. How much current will an HC-49 handle safely ? How about an
>> FT-243 ? Is there a one-tuber that is nicer to the crystals than another 
>> ?
>>
>> I really appreciate any help you can give. I know you folks have
>> probably answered these questions many times.
>>
>> Doug WA6VYN
>> ______________________________________________________________
>
> Hi Doug,
>
> Do you want to build a one stage power oscillator or do you want to
> build a one tube transmitter. If you use a tube that has two (or more)
> devices in one envelope you can realize a MOPA with one tube. Something
> like the 6U8A comes immediately to mind. Some of the Compctrons have
> three or more devices inside one glass tube (and more power than a 6U8).
>
> For the power oscillator there are some tuning tricks in the plate
> circuit that help the crystal survive. If I remember correctly some of
> the hams tune the plate circuit to the low frequency side of resonance
> to take it easy on the xtal. It may be the other way round. Some others
> put a light bulb in series with the xtal. Some do both. I didn't make
> good notes because my personal minimal transmitter starts at MOPA and
> goes up from there.
>
> 73,
>
> Bill  KU8H
>
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