[Fox_Tango] Re: FT 101 low output

[Ron]

I suspect that if your rig is eating new tubes, it needs to be
neutralized.
My FL-101 will run for hours with an issue.

---
Ron


W Sanders wrote:
> 
> Hey the list is alive!
> 
> I don't think it's wise to drive the FT-101 continuously for more than a
> minute or so regardless of the power level. I replaced me green band
> (original) finals with NOS GE tubes and ran PSK 31 for a few weeks. I never
> ran more than
> 35 W power output / 150ma plate (*) current and within weeks the output of the
> new tubes was down to 5 or 10 W. I even put a thermometer probe in the output
> fan duct to monitor temperature rise. (Like driving a Volkswagen by the EGT
> gauge - you only go so fast as to keep the EGT below a certain level. But I
> digress.) My problem is that the IC rose as power dropped. I am not sure I
> actually fried the new tubes but I think their capacitances changed so that
> the impednaces were all weird - seems like I had the Loading control at either
> 0 or 10.
> 
> I put the original final tubes back in. I think the power amp is designed so
> "close to the brink" in terms of operating the 6JS6Cs - which weren't really
> designed to run at HF frequencies and power levels - that anything other than
> CW and SSB duty cycles gets things so hot inside the compartment that
> component values drift. Remember what the manual admonishes: "continuous
> operation for more than 10 seconds may result in destruction of final tubes."
> 
> I wonder how many ops destroyed their brand-new rigs running RTTY back in "the
> old days?"
> 
> -Wiley KF6IIU
> 
> (*) From the schematic the metering is on the cathose side so you are really
> monitoring all current through the tube - plate and grid current, right? This
> is actually a good thing.
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