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THE AM BULLETIN BOARD => Class E Forum => Topic started by: vk3alk on September 12, 2022, 08:51:13 AM



Title: Another 80M Transmitter
Post by: vk3alk on September 12, 2022, 08:51:13 AM
Had these modules just laying around taking up space so it was either dismantling them for parts or making another TX....

Outputs 300 watts of carrier so not a big powerful Transmitter but useful enough...
Could probably do your legal limit using a bigger power supply and a little more heatsinking....
The RM10 cores in the PWM LPF run cool with modulation but may need larger ones at 400watts appox...

Has overload and SWR protection....

Uses Rods VMCD TX which goes well....

Happy with it .... nice transmitter ....  :)


Wayne


Title: Re: Another 80M Transmitter
Post by: K4RT on September 12, 2022, 08:36:30 PM
Wayne,

Thanks for posting the pics. Nice work. 300 watts is a respectable signal. Is there a modulator?

Brad K4RT


Title: Re: Another 80M Transmitter
Post by: vk3alk on September 12, 2022, 11:29:50 PM
Hi Brad...

Its a complete transmitter .... just plugin the AC mains ... antenna ... receiver with different muting methods .... Cro and unbalanced and balanced low level audio inputs....
Also a 12VDC output as well...
Uploaded the rear panel etc:

The little module on the left front is a switching regulator that has a variable output control from zero through to max power.
Has error amplifiers that the overcurrent and SWR protection go to..
The rear left is the PWM ( modulator ) and the right side is the TX module....
Added two 24VDC fans behind the PWM using the 12 volt supply so you cannot hear them just to keep all good during the hot summertime ...

I prefer using H Bridge TX modules but even with this VMCD TX you could connect any good or bad processor without blowing it up....

The SWR protection is a shutdown type.....
In time will change it to a rollback method ..... couldn't get it to work that way but will experiment. At the end of the day probably will figger it out I suppose .... ::)

Thats about it....

Ohhh I'm missing a screw on the left middle .... better fix that up  :)


Wayne





Title: Re: Another 80M Transmitter
Post by: KQ6F on September 13, 2022, 01:57:26 PM
Wayne -

Is that switching power supply an OEM module?  If so, can you post the make and model?

TNX.

Rod KQ6F


Title: Re: Another 80M Transmitter
Post by: vk3alk on September 13, 2022, 07:32:35 PM
Hi Rod...

The regulator is homebrew...

A Ham friend who is much better then me at making artwork designed the board using some program and ordered them through China...

Have uploaded one of my boards which is twice as big but works just as well...

Can send you the design via email if you like...


Wayne
AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands