This tube is utilized in a Gates FM 5H transmitter IPA. Just wondering what the maximum input power is for this tube, at FM frequencies. The National Electronics tube we are using does not come with a spec sheet. Can anyone provide a link for a suitable spec sheet, that provides some type of concrete evidence, regarding maximum input power(s)?
-
Get involved.
We want your input!
Apply for Membership and join the conversations about everything related to broadcasting.
After we receive your registration, a moderator will review it. After your registration is approved, you will be permitted to post.
If you use a disposable or false email address, your registration will be rejected.
After your membership is approved, please take a minute to tell us a little bit about yourself.
https://www.radiodiscussions.com/forums/introduce-yourself.1088/
Thanks in advance and have fun!
RadioDiscussions Administrators
4cx250b/7203
- Thread starter Brian Bowers
- Start date
This is a link to the tube specs.
http://www.r-type.org/pdfs/7203.pdf
http://www.r-type.org/pdfs/7203.pdf
Input as in DC input to the plate (500w) or RF drive in from exciter (about 2-3watts depending on Plate V and mode..in Class C, and with plate voltage at 1500, the drive drops to ~1.7 watts)
The Gates exciter provided about 10 watts (max) RF drive to the IPA. The Gates 20H required a full 10 watts. The 5H may require less IPA grid drive.
I'm sorry guys, I'm referring to the Harris FM-5K. The manual states that the 4CX250B/7203 tube operates in a Class B mode. I just don't want to overdrive it. This transmitter is kind of picky, because if it sees less than 8 MA grid current, from/on the IPA, a relay trips. Since there is no meter to read this grid current (all you can rely on is this relay dropping out), you can only back the exciter power down until the relay trips (usually around 6 watts). So just to be on the safe side, I'm wondering what the maximum power into the tube can be. Hopefully I know what I'm talking about here.
Class B mode is not as efficient as Class C and would require a little more drive for the same output...If it were me, I would maually close the relay with a sliver of wood, etc and adjust exciter for proper output of the IPA into the PA..You could always call Gates Air and ask tech support.
- Status