The AM Forum
March 28, 2024, 06:34:24 AM *
Welcome, Guest. Please login or register.

Login with username, password and session length
 
   Home   Help Calendar Links Staff List Gallery Login Register  
Pages: 1 [2]   Go Down
  Print  
Author Topic: Hopefully back at it  (Read 17782 times)
0 Members and 2 Guests are viewing this topic.
KQ6F
Member

Offline Offline

Posts: 124


« Reply #25 on: November 16, 2020, 07:11:40 PM »

Pat -

If I understand correctly, what you intend is to rework the transformer to get about a 7 ohm load resistance and apply about 60 volts to the RF deck.  That would cause 8.6 amps to flow - way beyond the capability of your power supply.

Rod
Logged
N4LTA
Contributing
Member
*
Offline Offline

Posts: 1075


« Reply #26 on: November 17, 2020, 01:33:27 PM »

No, I was thinking 15 ohms, but I will probably remain at 7 ohms as Wayne and run at a lower voltage. My amps that were lost in the fire ran at 125 volts or a little more as did Nigels.

Pat
Logged
vk3alk
Member

Offline Offline

Posts: 238


« Reply #27 on: November 17, 2020, 05:32:35 PM »

Hi Pat....

If it was my Transmitter would leave it at 7R .....
With your Power Supply levels you should achieve a comfortable power level of around 200 Watt carrier and fully modulate it....

Just a question .... is your 125 volt power supply variable and is it regulated ?
Wondering how you will tune up or check SWR and those things which are normally done at lower safe levels ....

Build your TX first before the Modulator so you know what the loading is and then you can design your PWM LPF accordingly etc:

It will end up a being a good AM Transmitter.... Cool


Wayne
Logged
N4LTA
Contributing
Member
*
Offline Offline

Posts: 1075


« Reply #28 on: November 17, 2020, 05:41:46 PM »

Yes - variable and current limited and I have a variable 0-60 volt 10 amp supply that I just got to replace some burned up stuff.

Both are nice current limited linear supplies.

The replacement cost insurance left me with some nice choices.

Pat
Logged
vk3alk
Member

Offline Offline

Posts: 238


« Reply #29 on: November 17, 2020, 05:44:30 PM »

Ohhh it seems to be one of those weeks...
I'm speaking without thinking through things...
Your Power Supply is only 120 volts at 3 Amps....

You will not be able to fully modulate your TX at 200 Watts ....

You may have to run at a lower power level or better still build another HV Supply...



Wayne
Logged
vk3alk
Member

Offline Offline

Posts: 238


« Reply #30 on: November 17, 2020, 05:49:12 PM »

Hi Pat...

I was posting as you were posting......

Ok on the variable supply .... great....

Just built it up and run at a power level that is comfortable for your supply etc: and maybe higher power can come at a later date  Smiley Smiley



Wayne
Logged
Pages: 1 [2]   Go Up
  Print  
 
Jump to:  

AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
 AMfone © 2001-2015
Powered by SMF 1.1.21 | SMF © 2015, Simple Machines
Page created in 0.051 seconds with 19 queries.