[TMC] Friday PAL 350 update

[Chris Bolkan]

Holy Shit Francesco!

I just looked at your QRZ page. Your "shack" is something else! Are you and
Nick England related? Brothers? Cousins? Between you and him I've never
seen so much absolutely cool equipment!

I'd be honored to have you check my tubes!

I'll drop you an email so you can send me your mailing address.

Thank you!

Best regards,

Chris



On Fri, Oct 22, 2021 at 4:50 PM Francesco Ledda <frledda at att.net> wrote:

> I can test your tubes. Where are you located?
>
> Best, Francesco K5URG
>
> Sent from my iPad
>
> > On Oct 22, 2021, at 18:22, Chris Bolkan <bolkyboats at gmail.com> wrote:
> >
> > Hi TMC lovers!
> >
> > I reassembled the amplifier after verifying that the screen grid bypass
> > capacitors are good. Powered it up to make sure everything still works
> and
> > it does.
> >
> > I tuned it up at 3.9 Mhz into a 50 ohm load. Tuned the drive to 3.9 mhz ,
> > then applied HV. Dipped the plate current with tune and peaked output
> with
> > load as drive was increased. Did this until plate current was 240 ma. At
> > 240 mA, power output was 50 watts, Drive level was 20, Screen grid
> current
> > read 0.
> >
> > I could probably roast weenies over the output tubes. It purrs along
> > nicely........at 50 watts.
> >
> > Once all tuned up I fiddled with the tune and load controls and saw
> > virtually no change in screen current. This is suspicious because I would
> > expect to see more happen here. But it doesn't.
> >
> > Could my finals be weak? Do these symptoms align with weak finals?
> > Everything seems to work so well and tunes up so nicely that I wonder if
> > the tubes are weak. I'm out of other things to try.
> >
> > I have no way to test these tubes because I do not have a known working
> amp
> > to check them with. Unless someone has more ideas of something to look
> at,
> > test or do, I am out of ideas except for testing the tubes.
> >
> > Without a known good amp, is there a way I can test these tubes? If
> > not.....this is a big ask, but is there someone willing to put my finals
> in
> > their known working amp and check their condition?
> >
> > Until I know the tubes are good (or not) I don't know what else I can
> > try, or even if trying other things makes sense.
> >
> > As always Thanks for all the help and advice.
> >
> > Best regards,
> >
> > Chris
> > ______________________________________________________________
> > TMC mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/tmc
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:TMC at mailman.qth.net
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list: http://www.qsl.net/donate.html
>
>