[WSWSS] For Sale - Partially Completed 432 MHz Kilowatt Amp & Pwr Supply

[Bob Kocisko]

Hello:

I have for sale a partially completed, high efficiency, K2RIW design 432 MHz
kilowatt amp & pwr supply.  The PA (pwr amp) & PS (pwr supply) are housed in
beautiful matching cabinets & are designed for either table top or portable
operation.  Price is only $350 US for both units.  The PA cabinet consists
of the RF deck & is probably 75-80% completed (the hard part is done) & the
PS cabinet is only abt 20% completed.  If you're interested in a tremendous
value & hv the ability & desire to complete this project, pse read on for a
detailed description.  Otherwise, thanks for reading & go ahead & delete
this long message now.  Sri for the length of this message but I can't post
it with an attachment on this reflector.

73,
Bob, K6PF


Detailed information for those of you who are interested follows.

BACKGROUND:

I purchased this partially completed PA & PS abt 4 yrs ago with the intent
of building tetrode KW PA's for 2m & 70cm which would share a common PS.
N6EDR, fm whom I purchased this, did a vy professional job of bldg the RF
deck & I knew this would save me a lot of time & money by not hv'ing to
start fm scratch.  However, I've bn concentrating on 2m EME & still hv not
made the time to complete this project. I just purchased an existing 70cm
EME station which includes an 8938 HPA & PS.  Therefore, I no longer hv a
need for the PA & PS being described & am willing to sell it for what I paid
for it 4 yrs ago.

WHAT IS INCLUDED:

The PA & PS are housed in beautiful matching blue cabinets with cream
colored panels.  Each cabinet measures 17"W x 7"H x 9.5"D.  Due to the
weight of the PS, that cabinet includes side handles for easier carrying.

The PA cabinet includes the following:  This unit is probably 75-80%
completed.  Mounted on the front panel are 4 vy nice verniers with knobs for
tuning the grid & plate ckts, green & red pushbutton on/off switches & 2
meters (0-1ma & 0-1A).  A Universal Electric Co. 115vac 3100rpm used blower
is included but not mounted.  A larger blower would probably be btr.

The RF deck looks like it's almost completed & has the following items
mounted on it & already wired:  2 x 4CX250B tubes & sockets, solid brass
anode strip line, grid circuit with brass grid line, all tuning & coupling
variable caps, in & out coaxial connectors, 2 coaxial relays, feed-thru
caps, some meter shunts & terminal strips.  It looks like all of the RF deck
metal work & hardware mounting are completed.

Still to be completed in the PA cabinet are:

1.  Mount RF deck inside cabinet.
2.  Mount blower & route airflow in & out of RF deck & cabinet.
3.  Connect 4 verniers to all variable caps with flexible coupling shafts
(included).
4.  Wire up meters & install a meter switch if desired (not included).
5.  Route all voltages & RF cables thru cabinet.

The K2RIW design is thoroughly described in the April & May 1972 issues of
QST & an article in the UHF Microwave book.  Also, the ARCO's version of the
K2RIW amp is also described in the VHF/UHF DX Book.  Copies of all articles
& Eimac spec sheets on the 4CX250 B's & R's are included.

The K2RIW design uses a stripline ckt with 2 x 4CX250B's in parallel.  A
chart in the article indicates 850-900 watts output with 30 watts drive &
700 watts out with 20 watts of drive.  Efficiency is vy high (70-75%) so
input pwr is over 1KW.  Voltage requirements for the PA are 2000vdc @ 500ma
for the anodes, 300vdc @ 50 ma for the screens, -90vdc bias with 50ma
current sinking capability & filament voltage.

The PS cabinet (very heavy) includes the following:

This matching cabinet has a 500ma meter & on/off pushbutton mounted on the
panel.  A heavy aluminum plate inside has a Collins plate xfmr mounted on
it. This xfmr has 2 x 115vac primary windings & 2250 vrms center tapped
secondary @ 565ma.  Also mounted on this AL plate is either a filament xfmr
or filter choke (not sure).  The marking on it says Elect Corp of America
South Gate P/N ECA 5012.  2 leads are visible on one side & I can't tell if
thr are any leads on the other side without removing it fm the AL plate.

Also included is a capacitor bank with 6 x 410uf @ 450v electrolytic caps in
series.  These are mounted on a plexiglass plate with resistors but the
entire capacitor bank is loose & needs to be mounted.  THe bridge rectifier
diodes are mounted on a heat sink which also is loose & needs to be mounted
somewhere.

Other than for the capacitor bank, nothing in the PS cabinet is wired.  A
screen & bias supply will be needed (not included) along with a filament
xfmr if the item mentioned is a filter choke & not a filament xfmr.  The PS
unit needs to be wired & completed & probably is abt 20% done.

CONCLUSIONS:

I believe this is an exceptional value for someone that has the ability &
desire to finish this project.  The price is $350 US total for both the PA &
PS + shipping & insurance fm zip code 92708 (So. Calif).  Obviously, pickup
is preferred but I can box & ship each cabinet separately.  The parts that
are included certainly would cost much more than $350 if purchased + a lot
of time has already gone into the construction that has bn completed so far.

I will take several photos but don't hv a digital camera.  If anyone is
interested in photos, pse let me know.  As soon as I get the film developed,
I will scan them into my computer & can email them to you.

If you've gotten this far, many tnx for reading this message.

73,
Bob, K6PF
DM13ar