[Amps] AL-1500 pi-network capabilities

[R.Measures]

On Aug 30, 2004, at 3:16 AM, Pete Smith wrote:

> I've been toying with the idea of adding a modern amp to my SB-220 for 
> SO2R operation.  One of the things I really like about the SB-220 is 
> that its pi network has sufficient matching range on the low bands so 
> that, for example, I can run my 40M yagi, which is cut for the CW end, 
> up well into the phone band, or run my 80m K3LR array, which is cut 
> for 80CW, up to at least 3900 kHz.
>
> Does the AL-1500 have similar matching range, or will I find myself 
> more restricted?

Pete -- The Pi output is similar.  However, before taking an AL-1500 on 
a trip, it might be a good idea to install a VHF parasitic suppressor 
in the anode circuit.  I would also add a glitch R in the HV+ lead,  
for which I would use 2, 10-ohm 10w, glass-coated resistors in series.  
As for the suppressor, if it does not get infernally hot on 28MHz, the 
Q is too high.   If the AL-1500 has a "neutralization circuit", I would 
remove it.  ///  -  note 1 -  there is no way to neutralize a HF 
amplifier at the always-present VHF resonance in the anode circuit.   
note 2 - This (RCA Transmitting Tube Manual) "neutralization circuit" 
adds a feedback path between the anode/output and the cathode/input, 
however, in a g-g amplifier, this is not a very good idea, unless the 
plan is to make it into a VHF osc.
-cheers-

>
> 73, Pete N4ZR
> The World HF Contest Station Database
> was updated on August 2, 2004
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>
Richard L. Measures, AG6K, 805.386.3734.  www.somis.org