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Title: TRANSMITTER LOOKING TO COME TO MY QTH Post by: W2PFY on October 29, 2020, 05:40:38 PM A couple weeks ago I purchased 4 brandy new 4PR65A/8187 Amperex Electron Tubes. The reason I did this is I don't have anything that uses them and they are bait just waiting for some unsuspecting transmitter to be trapped by their presence. Most would think that a transmitter that would use them would be somewhat small but you would be fooled by the Navy and the BC industry where 3 were used in a screen modulator for a 50 KW rig in the latter.
But I am hopeful that I may find what was known as an Embassy transmitter that were used in some American embassy's which were very compact and were in two units consisting of a transmitter and a separate power supply. It covered 2-30 MHz. I only ever seen one such transmitter. It was on sale on eBay years ago and was in the American Embassy in Italy at one time. It was in pristine condition but my bid failed and it went to Australia. Does anyone know the model of the transmitter I am describing? Here kitty kitty, I mean transmitter!! Title: Re: TRANSMITTER LOOKING TO COME TO MY QTH Post by: WBear2GCR on October 29, 2020, 08:48:42 PM They looks suspiciously similar to 4-65s?
And, it is... pulse rated. Up to 15kv!! Whheeeeeee! Do we need a special xmitr to use this tube?? Title: Re: TRANSMITTER LOOKING TO COME TO MY QTH Post by: Tom WA3KLR on October 29, 2020, 09:12:26 PM Terry,
I am thinking of the Gates CMG-1, uses two 4-65's, 3 chassis in one rack cabinet: https://worldradiohistory.com/hd2/IDX-CATALOGS/IDX/Gates-Harris/Gates-Catalog-96-1965-OCR-Page-0203.pdf Title: Re: TRANSMITTER LOOKING TO COME TO MY QTH Post by: W2PFY on October 30, 2020, 08:03:44 PM Well Bear, the tubes might be good in a digital modulator for a class E tube rig. Is there such a thing as Class E in tubes? No special transformers needed for what I am doing but it makes me wonder how they were used in military radar sets as they do not go all that high in frequency and by 1962 they were using microwave freqs. Maybe they were just the SW for the magnetron?
Hello Tom, nope that's not the one although I would mind finding one like you have shown us? I never heard of that set. The problem with a lot of transmitters that were made for the military is that some were never released for sale as surplus or people just parted them out, to make something smaller to keep the good wife Mable happy? Title: Re: TRANSMITTER LOOKING TO COME TO MY QTH Post by: WBear2GCR on October 31, 2020, 10:33:09 AM Ask QIX, he had a series modulated PWM rig, all tubes, at one time...
No mod iron required. Class E with tubes? Dunno. You could make a whiz-bang Tesla coil using those to modulate the coil!! _-_-bear Title: Re: TRANSMITTER LOOKING TO COME TO MY QTH Post by: w1vtp on November 08, 2020, 01:26:04 PM A couple weeks ago I purchased 4 brandy new 4PR65A/8187 Amperex Electron Tubes. The reason I did this is I don't have anything that uses them and they are bait just waiting for some unsuspecting transmitter to be trapped by their presence. Most would think that a transmitter that would use them would be somewhat small but you would be fooled by the Navy and the BC industry where 3 were used in a screen modulator for a 50 KW rig in the latter. But I am hopeful that I may find what was known as an Embassy transmitter that were used in some American embassy's which were very compact and were in two units consisting of a transmitter and a separate power supply. It covered 2-30 MHz. I only ever seen one such transmitter. It was on sale on eBay years ago and was in the American Embassy in Italy at one time. It was in pristine condition but my bid failed and it went to Australia. Does anyone know the model of the transmitter I am describing? Here kitty kitty, I mean transmitter!! Terry Check with Larry NE1S. He is building a pair of 4-65's xmtr. I'm emailing you a copy of his description of his progress. Check your regular inbox Al |