The AM Forum

Good Morning fellers....
OK, any of you guys successfully put a Globe King 400 on 160M?
Following the Military manual, the instructions call for padders
on all the coils...which I've done...I get good "dip" on OSC & BUFFER
stages, but no GRID DRIVE....
The manual says "160M JVL coil padder cap (65pF) and LINK MODIFIED...
but no description as to how the JVL link is to be modified!

The rig works FB on 75m....
Using a WRL 755A VFO....
73
Steve
8TOW

W1CKI has one on 160

Hi Steve,
I just go my Globe King 400 working on 160M this week. It was pretty straight forward with the appropriate coils.
Both the OSC and BUF use homemade coils that are similar to B&W MEL 160M coils.
The PA Grid uses a Bud 160M with a fixed center link and a 50pf padder capacitor that was added.
The PA Tank uses a B&W 160 TVL coil and a 75pf HV padder capacitor. The variable link has 6 turns with a 1500pf Mica Transmitting capicator in series to directly feed 50 ohm coax.
I also replaced the twin lead cable that connects the BUF link and PA Grid link together with 50 ohm coax (per Bob W2ICQ's suggestion).
I have been able to tune up with 50ma PA grid drive and 300ma PA plate current into my coax-feed 160M inverted vee without any problems.
73 - Jerry W1ZB

Hey Jerry, glad to hear you got your GK 400 down on 160m too!
My solution was achieved once I bypassed the 1000 pF cap that is in series
to ground in the grid link circuit of the V70D's.
I removed it, now the "END LINK" coil of the 807 output is directly
coupled to the "CENTER LINK" of the grid coil for the V70D's.
Plenty of grid drive now...geez, up to 75 mA if I wanted it!
Nice and stable, all the way through. Did your GK have a 1000 pF cap in
that circuit to ground? Also, note that most of the early
link coupled circuits show the "LINK" not grounded. This is grounded on one end...
of the link at the JEL coil. Seems odd...wonder why?

For the PA output, quite easy to link to the coax. 1000 pF door knob in series to
ground and a 12 turn swinging link...plenty of PA Plate I.....
GL es cu on 160m
73
Steve
8tow

One side of the link doesn't have to be grounded.  Mine just float free.  I don't even use coax to connect between them, just a twisted pair made of flexible stranded hookup wire.  The plate coil in the driver stage has a swinging link, which is what I use to adjust the grid drive.  With fixed links on both coils, you can set the grid drive by adjusting the number of turns on one of the links.

I was wondering about that Don...I plan to replace the interconnecting wire between the stages with
some "twisted-pair" in the future...and think I will try it "un-grounded" also.
In my HB T-40 PP transmitter, the coupling between stages is not grounded, just a twisted pair and
it works just fine...don't know why WRL did that little deal in the GK 400 with the series cap...
must have thought it would provide a more effective Z match between stages
73 Steve 8TOW

Steve - My GK also had the 1000pf cap in series with the PA Grid link coil. Removing it did not really increase to amount of grid drive in my unit, but I took it out anyway. Increasing the number of turns for the link in the BUF coil (as Don stated) did make a big increase in grid drive. I also added a drive control pot (25K) to the 2E26 (or 807) screen grid to adjust grid drive more easily. The 50 ohm coax connecting the two links is grounded at one end, but I don't think that it's really necessary now.
BCNU - Jerry W1ZB