[600MRG] WD2XSH/6 630 meter station up for sale.

[Pat Hamel]

I asked permission before posting this.
Due to advancing old age, I find it necessary to start some long-term
planning that involves insuring that my 600 meter equipment is not put in
the dumpster when something makes it necessary for me to move to a care
facility. Local hams will know of ham "stuff" but you are the most likely to
be interested in it.

The station is up for sale together.
Parts include the ICOM R-75 receiver with sync AM, stable local oscillator,
and two 250HZ filters (one in each IF). 
The receiver had an audio problem a year or so ago and was repaired at the
ICOM place in Michigan. 
I have a one-inch thick binder with the operations and service manual.

The transmitter consists of three sections and has been on transmit 11,936
hours with no interference problems.

First an "N3ZI DDS VFO Special" in it's own box with documents.
There is no power switch on the box, only a good fuse. For stability the
power is never shut off.
I use it for CW and QRSS.
As an alternate digital VFO, I also include a Motorola channel modem (it is
a USB generator designed to be frequency programmed with jumpers on a
plug-in board).
With 800HZ PSK carrier audio from the sound card into it, it is now jumpered
to provide 508.800kc USB PSK. There is a receiving channel on the board
which I did not use.
With a multi-position switch with 11 decks you can program some digital
suppressed carrier frequencies into it but not all the frequencies. 
The documentation I have has come from Ralph (WD2XSH/7).

The exciter is the second version I have built. 
It is in a Heathkit monobander case.
It was designed to run full-bore as a stand-alone 5 watt ERP ham rig (70
watts RF out) or drive the 811 amp with about 20 watts.. 
For driving the final the bias is turned up on two of the 6GE5 tubes to cut
them off. 
To get a clean 70 watts out for future ham use, requires two updated
Heathkit power supplies and a combiner box which will be included.
Inside the exciter box is a 12AU6 driving a 12BY7 which drives three 6GE5s.
The final PI-L network (for a clean signal) has coils wound on "E" cores.
There is a fan with ducting to cool the 6GE5s. Spare good tubes will be
included. Individual bias pots allow balancing assorted 6GE5s.
The exciter is keyed with a transistor circuit to enable relay sequence
keying. It can be keyed by a computer serial port and / or your keyer. 
The T/R coaxial relay which switches the transmit antenna between the amp
(or exciter) and receiver is included, as is the receiver protection box
which also allows selecting a separate shielded loop antenna

The final RF deck is shown in QST march 2008 and has been updated since that
picture. The 1250 volt power supply is not shown.
The circuit is four 811 tubes running at 1250 volts (the tube spec sheet
value) topping out at 600 ma (the power transformer is rated at 700 ma.) 
For cancellation of the second harmonic, they are run in push-pull parallel.
The original four matched tubes lasted from early 2007 to 2012.

The circuit is fully neutralized.
The circuit has provisions to meter the grid current of the individual tubes
which clearly shows any imbalance before it gets too bad.
Right now the tubes in the amp are mismatched. 
The additional mod to put in balancing pots or get a matched set of tubes is
the final indicator that I need to sell it off rather than have the kids
scrap it.
The grid circuit is a broad band transformer which has worked fine for a
couple years with the tubes running class "B" linear. 
An attempt to get 70% efficiency class "C"  without changing the transformer
failed. I just don't have the math .
Bottom line - it is a 300 watt clean linear RF output for about a KW DC
input amp...several spare 811's are included.

The low-pass filter is mounted in the antenna-tuning box it helps both
receive and transmit. It is included, as is the remote RF ammeter and main
RF ammeter.

How much ?
The ICOM R-75 without the narrow filters or stable oscillator goes for about
$500
There is no way to figure the value of the parts and work that I have put
into it, 
Many parts like the RF deck chassis and box were donated to me.
The transmitter is built by a ham with parts that were available and hand
tools, not a machine shop. 
I will add in the shielded loop and the antenna loading coil for pick-up.
You can see it work if you like. The documentation is hand-drawn.
I am located on the Mississippi gulf coast between New Orleans La and Mobile
Al zip 39560.
There are casinos in all directions. The weather is not South Florida, but
the costs are not that outrageous.
I figure I have $700 dollars into the R-75 and it's add-ons; so give me $750
for the station and spares you pack-you-haul.
Pat Hamel W5THT & WD2XSH/6