[Yaesu] Progress and internal tuners

[Adam Farson]

 Hi Jay,

Actually, there is a sound argument for ensuring that an SSB transmitter
always "sees" a 50-ohm resistive load.

To re-quote a key sentence from Sabin, "HF Radio Systems & Circuits": 

The collector-to-collector (or drain) load impedance must be maintained as
close to resistive as possible [to ensure optimum linearity]. This in turn
requires optimizing the output wideband transformer(s), combiner (if used),
and low-pass filter passband VSWRs to as low values as possible.

Another issue is that mis-termination of the low-pass filters following the
PA will compromise their amplitude/frequency response, leading to a
degradation of harmonic suppression.

Cheers for now, 73,
Adam VA7OJ/AB4OJ


-----Original Message-----
From: Jay [mailto:ad5pe at sbcglobal.net] 
Sent: 14 September 2006 10:23
To: farson at shaw.ca; 'Icom Reflector'
Cc: 'Yaesu Reflector'; 'Yaesu Contesting Reflector'
Subject: RE: [Yaesu] Progress and internal tuners

You can have a small radio and limited tuning, a small radio and an external
tuner, or a big radio with wider tuning.  Or of course a big radio and a
bigger external tuner.

Then again, there's always remote antenna switches and resonant antennas,
right....


73,
Jay
AD5PE 

-----Original Message-----
From: yaesu-bounces at mailman.qth.net [mailto:yaesu-bounces at mailman.qth.net]
On Behalf Of Adam Farson
Sent: Thursday, September 14, 2006 12:14
To: Icom Reflector
Cc: Yaesu Reflector; Yaesu Contesting Reflector
Subject: RE: [Yaesu] Progress and internal tuners

Hi John,

With the shrinkage in the size of HF radios, the amount of "real estate"
available for the autotuner has become smaller. The T-network components
have shrunk accordingly, so current autotuners have much less tuning range
beyond their advertised spec of 16 to 150 ohms (VSWR = 3:1 max) than their
predecessors.

Manufacturers are required only to hold to their advertised specs, no more
and no less.

Cheers for now, 73,
Adam VA7OJ/AB4OJ



Scanned for viruses by Blue Coat
http://www.WinProxy.com/
_______________________________________________
Yaesu mailing list
Yaesu at mailman.qth.net
http://mailman.qth.net/mailman/listinfo/yaesu



Scanned for viruses by Blue Coat
http://www.WinProxy.com/