[Amps] *** SPAM *** Re: Pi-L Network

[Tom W8JI]

> No, I was thinking of 7.5kW and upwards transmitters, 
> where frequency changing wasn't that common ( once on a 
> frequency, it would be there for hours, and each tx was 
> likely to only need about 6 channels anyway), wideband 
> antennas such as rhombics were used, and the max SWR at 
> the tx was limited to 2:1 max.
> The HF marine bands are about as narrow as ham bands (in 
> some cases much narrower), so the amount of retuning 
> between band ends is in practice negligible. The exception 
> is the MF band: in theory (and for Type Approval purposes 
> in Europe), transmitters were required to operate over 
> 1.605 to 3.8MHz, but in practice, after WW2, frequencies 
> used were mainly limited to 2.009 at the bottom 
> (International ship-ship) up to around 2.8 or 2.9 MHz. For 
> Type Approval, the antenna load was 10 ohms in series with 
> 250pF. In AM days, there were some Greek fishing boat 
> frequencies above 3MHz, but not many - there was some (but 
> very little real demand) requirement to cover up to 4.2MHz


And you looked at the tank values and know the systems 
functioned as Pi-L's and not double L's?

What was the intermediate impedance at the loading 
capacitor?

How do you know they did it for harmonic suppression and not 
some other reason?

73 Tom