[1000mp] Quadra

[Adam Farson]

John,

Please have a look at the Quadra page on my site. There is a lot of
information on the Quadra there.

http://www.qsl.net/ab4oj/quadra/quadra.html

The ARRL review of the Quadra is in QST, January 2002; it is also on the
ARRL members' web page.

http://www.arrl.org/members-only/prodrev/pdf/pr0201.pdf

To address some of the points raised in the current thread:

Whilst still working at Yaesu Tech Support, Mike Kruger, N6MIK, assured me
that the high-speed T/R relays in the Quadra would support QSK CW operation.

I have a Quadra which has been in my station for 3 years, and it is working
flawlessly. The exciter is an Icom IC-756Pro. I have measured IP3 = -34 dBr
at 1 kW PEP 2-tone, vs. -32 dBr at 1.0 kW PEP 2-tone output, as measured in
the ARRL test report. I would not recommend driving the Quadra to much more
than 1.1 kW PEP output; 1 dB additional output can degrade IP3 by 4 to 5 dB.

As the transfer characteristic of the MRF150's effectively determines the
system IP3 and IP5, operating the exciter in Class A will not noticeably
improve system linearity.

When using the Quadra with a non-Yaesu exciter, a carrier of about 80W is
required for auto bandswitching and autotuning. To accomplish this, the
"Band Data 2" keying line of the amplifier is connected to the "send" line
of the exciter. The exciter is then placed in RTTY or FM mode to supply the
carrier. This is described in detail in the "mini-review" on my Quadra page.

The only automated feature which does not carry over with a non-Yaesu
exciter is automatic antenna selection by band.

I am not too troubled by 1.0 vs. 1.5 kW output. 1/4 S-unit (1.5 dB) less RF
output is, in my view, an acceptable price to pay for eternal liberation
from the shackles of vacuum-tube technology. (Must concede, though, that
tube amplifiers still have lower IP3 than solid-state designs.)

The MRF150 is still listed in RF Parts' catalogue.
http://www.rfparts.com/mototran.html

M/A-Com now makes the part. http://www.macom.com/data/datasheet/MRF150.pdf
A Japanese equivalent (SRF150) is also available from Yaesu Parts and other
sources.

Do note, though, that as long as the Quadra is operated within its design
parameters, with properly calibrated ALC, the MRF150's should last the life
of the equipment. They are operated with about 20% headroom, and the
amplifier runs cool at 1.0 kW output in SSB mode. It is absolutely
imperative that the ALC be connected and calibrated to limit output to 1kW.
The ALC is the amplifier's first line of defence; the protection subsystem
operates by pulling down the ALC line to reduce  the driving power. Please
do not listen to the siren song entitled "You don't need ALC".

Thee Quadra requires at least 80W of drive to tune or bandswitch correctly.

Best 73,
Adam, VA7OJ/AB4OJ
North Vancouver, BC, Canada
http://www.qsl.net/ab4oj/
Note new e-mail address:
mailto:farson@shaw.ca

-----Original Message-----
<snipped>

Hi, Would like any comments on the quadra amp, pro or con. I am looking
into getting one to use with my MarkV and FTV-1000 6 meter transverter.
Thanks- John