These days, you typically build what you have or can get parts to complete. 4-65's seem a poor choice, high voltage and low power.
If you were to build an RF deck that ran 3000 volts, its best to build a modulator that runs 3000 volts, otherwise the mod transformer has a huge voltage difference between primary and secondary. You would also likely have a very large impedance difference between primary and secondary. Say the 811's run 1500 volts, that's 12.4 K ohms, run them at 1200 volts and its around 10K. The 4-65 at 2500 volts and 110ma is at 22.73K ohms. Most setups have it the other way around, with the modulator being higher than the RF side. You would need a multimatch mod transformer so you could turn it around. I have built a pair of 813's modulated by 4cx250b's, works good, 2000 volts on both. I built a push pull 812 rig modulated by 811's, worked very well. 1500 volts on both... I also built the 3x 4D32 rig modulated by 811's, the 4D32's run 1250 volts, same as the modulator. Works good. What the 4-65 wants is a pair of 75TH's, very rare tubes! Brett N2DTS ______________________________________________________________ AMRadio mailing list List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body.
