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Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Firefox wrote ...
Three big transmitting tubes for 36 dollars with a socket. They look good with no visual burns or blemishes, and the dealer says they test out good.
QB3-300A is a very well-known VHF power tetrode. As you would be running it very far below its design frequency, you should be able to run it with a greater input than the data sheet without risk of over-heating.
Registered Member #1104
Joined: Tue Nov 06 2007, 07:38PM
Location: Wisconsin, United States
Posts: 34
If anyone is looking for cheep vintage ac flybacks: I have found a seller on eBay that lists four flybacks every week. I have already bought from him and they worked fine for me so I just felt like sharing the information. Here is the latest listing
Registered Member #33
Joined: Sat Feb 04 2006, 01:31PM
Location: Norway
Posts: 971
Here are some quite cheap CM300s on ebay. I thought I'd share this with you all since I know CM300s have been a bit hard to come by on eBay lately, especially the CM300DYs without the built-in current limiter.
I've been doing some datasheet reading as I'm thinking of buying some myself. These are the -28H variety, as opposed to the much more common -24H variant. This means that the Vceo breakdown voltage is 1400V instead of 1200V. What's sacrificed is slightly higher conduction loss and slightly longer turn-off time, though they are overall still a bit faster than CM600s. The higher voltage rating allows a higher bus voltage, which means less current for a given power, and this will probably compensate for the slightly higher conduction and switching loss. If using the predikter, swithcing losses should not be so much of an issue anyways.
I am not affiliated with the seller, other than having bought some stuff from him in the past, just thought I'd share this with you as I know some of you have been on the lookout for CM300s.
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only $500!...
