[Elecraft] time for KPA1500 - but why "no tubes?"

[Mike Harris]

Quite a few years ago I was running the comm's on one of the British 
Antarctic Survey bases (Adelaide Is).  My main TX used a Racal amp with 
3 x 4-400 in parallel (if I remember correctly).  It used a Pi-L 
network.  That network quite happily matched 20:1 SWR if necessary.  The 
tuning was rather critical but in other respects all was normal as far 
as the tubes were concerned. The coax (RG-8 type) from the TX to the 
balun would run very warm in those circumstances and sag from the ceiling.

Not desirable I admit but necessary to broadcast safety critical WX 
forecasts to remote sledging teams on a frequency in the 2MHz range that 
the antenna was never designed for and seldom used.

Regards,

Mike VP8NO

On 21/02/2012 04:14, Ron D'Eau Claire wrote:
> Well, Don, it's been a number of years since I homebrewed an amp, but from
> what I recall a pi-net wouldn't meet the later FCC regs and a Pi-L network
> only sufficed over a fairly narrow matching range.
>
> By the 1970's I was counting on my outboard "antenna tuner" that matched my
> open wire feeders to provide the added spur suppression to meet FCC regs
> even though I was still using a tunable Pi-L network on the output of my
> homebrew rig.
>
> 73, Ron AC7AC