[Swan] Question

[Dave Meitzen]

Great dissertation !! Thanks you for taking the time.

I should be able figure out what is going on .
Best Regards
Dave 

-----Original Message-----
From: swan-bounces at mailman.qth.net [mailto:swan-bounces at mailman.qth.net] On
Behalf Of Robert Balonis
Sent: Saturday, August 26, 2006 10:15 AM
To: Discussion of equipment manufactured by Swan
Subject: Re: [Swan] Question

Hi Dave

The PSU-3A was is the power supply that has the same physical cabinet
appearance as the 700S transceiver.  There is also a PSU-3, but it's cabinet
design is similar to that of the 117XC power supply, which matches the 700CX
transceiver in appearance.  The internal electronics components layout of
either of those two PSU units is different from the 117XC in that it doesn't
use the "black box" 117X configuration packaged within the cabinet.
However, I believe the circuit design, output voltages and current
capabilities are near identical to the previous 117X/C power supplies, so
the RF power output should not be a function of the power supply, regardless
of which power supply is used.

I think the 700C is rated at 550 and 350 W (SSB and CW respectively), so if
properly aligned and in good condition, the maximum expected outputs should
be in the  330 W and 210 W (assuming 60% efficiency at best).  The Swan
transceiver model number does not necessarily correspond to power rating -
in some cases the rating was greater
(350/C) and in some cases lower.  Note that the 700C uses 6LQ6 finals,
whereas the 700CX uses 8950 tubes, with a rated dc input of 700 and 400 W.

So, the 180 CW is quite reasonable, although the SSB is lower than I'd
expect given the CW power output - if possible, it would be nice to monitor
the output with a scope to do at least a qualitative check to insured that
the SSB peak(s) are indeed the same amplitude as the CW signal to confirm
the wattmeter's readings.  I'm not familiar with the Bird wattmeter, but a
complicating factor with any wattmeter is measurement accuracy - Assuming a
wattmeter has a 5% FS reading accuracy and a 500 W range is used, then the
measurement has a +/- 25 Watts error range.  Worse yet, any measurement
error will not necessarily be consistent/linear between modes (e.g. CW/SSB)
and with changes of frequency (e.g. 20 M/40 M) - so its possible for the
meter to be operating perfectly within specs and to show a reading 25 W too
high on CW and 25 W too low on SSB (or between two bands), a 50 W
difference!  If the measurement is not taken with a 50 ohm dummy load (other
than a SWR = 1::1), the reading will also be erroneously high due to the
reflected power component - that error is progressively larger as SWR
increases.

Note that the output on the higher bands, especially 10 meter, can be
appreciable less than what is achieved on the lower bands, even when
everything is properly aligned and in good condition.

Regards, Bob  NB3W

On Aug 25, 2006, at 3:38 PM, Dave Meitzen wrote:

> What power supply was paired with the SWAN 700 S transceiver. I am 
> using a
> CX-117 and it seems the max power out is around 180 watts key down -- 
> same in SSB on a peak reading Bird. I expected more. I tested two 
> different sets of finals with the same results. Power supply has been 
> rebuilt.
>
> Thanks
> Dave
>
>
> _______________________________________________
> Swan mailing list
> Swan at mailman.qth.net
> http://mailman.qth.net/mailman/listinfo/swan
>

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