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Re: Building my first amplifier. Where to start?
I'm sure you'll get a lot of input from real experts today, but I will give you a few high level comments.? Check out w8ji.com and read everything there about amplifiers.? Tom designed many tube
By Floyd - K8AC · #39842 ·
Building my first amplifier. Where to start?
Hi guys, I have been subscribed to this list and reading messages for some time, but I believe this is my first message, so hello all. I am a ham based in the UK and have been interested in amplifiers
By desmond auld GI0UTE · #39841 ·
Re: SB-206
Merry Christmas Warren. Sent from the all new AOL app for iOS
By Louis Parascondola · #39840 ·
Re: SB-206
Gentlemen, I want to thank you all for your input and help and especially to Lou for giving me some critical information. I gave the amp a road test today with a friend on 6 meters and he said it
By NI5L <ni5l@...> · #39839 ·
Re: SB-206
OK, thanks for clarifying that, Lou, as it wasn't clear before. 73, Steve K0XP
By Steve · #39838 ·
Re: SB-206
NO NO NO. Not grid driven. ?Cathode driven! Neither?Carl or myself did grid driven! ?It was cathode driven. ?Yes I know 20?watts drive sounds crazy but handling the bit of positive feedback with
By Louis Parascondola · #39837 ·
Re: SB-206
Yup; he was never real open about how he did some of the "successful" schtuff he was able to accomplish. So, Lou: are you saying that you believe Carl converted this "SB-206" to full grid-driven
By Steve · #39836 ·
Re: SB-206
Yup! Leave well enough alone. Sent from the all new AOL app for iOS
By Louis Parascondola · #39835 ·
Re: SB-206
Yeah...I suffer from mess-with-it-itis sometimes but not in this case.? :) If it ain't broke, don't fix it. Warren
By NI5L <ni5l@...> · #39834 ·
Re: SB-206
There should be about 70-90 ma. ?of idle current. I¡¯d leave it alone. Sent from the all new AOL app for iOS
By Louis Parascondola · #39833 ·
Re: SB-206
Thanks for that, Lou. And I re-read the meter explanation in the Heathkit manual and saw what you said. The end of the white range is 100 mA. This may or may not be an issue but I do not show any
By NI5L <ni5l@...> · #39832 ·
Re: SB-206
Skip, he is reading the grid current wrong!!!!!! ?THE SB200 amp does not have a graduated scale for grid current!!!!!! It only has a white area as a safe zone. ?The last mm of the white zone is 100
By Louis Parascondola · #39831 ·
Re: SB-206
Warren, at 50 mhz the neutralization on 572b tubes?is way out in outer space. ?It¡¯s bad enough on 10 meters let alone on 50mhz. ?That said, you can¡¯t expect a dip in the plate at maximum
By Louis Parascondola · #39830 ·
Re: SB-206
Chuck, The grid question is a good one and there is NO schematic of the conversion. It is written on the "manual" page in big script that there is no schematic. That is part of the reason I am puzzled
By NI5L <ni5l@...> · #39829 ·
Re: SB-206
This is interesting¡­was this amp modified for grid drive instead of grounded grid? Another possibility is that there could be a bit of positive feedback, not enough to cause self oscillation but
By Chuck Neal · #39828 ·
Re: SB-206
Steve, With no REL PWR function, I have just been peaking everything up using a watt meter. Like you, I am a little bit curious as to why it only takes 18 watts of drive to get 600 out. I just wrote
By NI5L <ni5l@...> · #39827 ·
Re: SB-206
Lou, I am tuning it to keep the grid current at 500 mA or less. The white area tops at 500 mA so that is what I have been referencing. This is a very touchy tank circuit! The amp came with some pencil
By NI5L <ni5l@...> · #39826 ·
Re: SB-206
Something doesn't sound right... you shouldn't be able to get 500 mils grid current and still have working tubes, ESPECIALLY with only 18 watts drive... That's a RIDICULOUSLY-LOW amount of drive; most
By Steve · #39825 ·
Re: SB-206
The grid current?isn¡¯t 500, it¡¯s has?nothing to do with the scale reading. ?As long as it¡¯s in the white area it¡¯s ok. ?With the 572b tube it¡¯s the temperature of the plates that is the
By Louis Parascondola · #39824 ·
Re: SB-206
If his license expired that long ago , his e-mail is not valid any longer, and his phone is disconned... that doesn't bode well. If I still lived in Mashachewzits, I'd take a drive up there to see
By Steve · #39823 ·