[AMRadio] RE: Receiver update.

[Brett Gazdzinski]

Russ,
I looked last night, and I only have one 6K7, and its the 
RF amp in the homebrew receiver.
So this is something I also need spares for.

I think the receiver is done except for the front panel.

I ordered a kiwa 5.5kc filter module.
It has built in input and output amps and requires about 5 to 30
volts DC to work, and replaces an IF transformer.
Some changes need to be done to add it to a tube receiver so 
it is not in the B+ or AGC feeds to the tube...I will see
how it works...

I think I will skip the xtal calibrator, and maybe the BFO,
as I don't really see any use for them.
Maybe add a bfo type circuit using a 455 KHz xtal,
so I can zero beat signals easy.

I do have one problem with the receiver.
The first power transformer I used has a 340 volt
output (DC) and that is too high.
I only need about 130 volts, and had BIG dropping resistors
between it and the VR tube that got very hot.

The only other lower voltage transformer I have on hand 
has a 260 volt DC output, and works much better, but
only has a 3 amp filament tap, and the high voltage is only
good for 90MA, so I cant add too much stuff to the receiver
until I find something a little better.

As it is, I run one of the 6SN7 tubes off the 5 volt winding
and it seems to work fine.
The B+ drain is up around 80MA, mostly due to the VR tube.

I am toying with running the thing off directly fed
110 volts like the Scott does.
A diode, a choke, a big cap, and the VR tube....
I should test this...

I also have to see if I need a separate buffered IF signal output
for the O scope, so the drain may go up.

I also have a problem as to where I can install the receiver
in the shack.
On the desk would be best, but I don't have a good smaller
cabinet with a door in the top.
I do have a couple of DX100 cabinets, and a 32v3 cabinet,
but they are the wrong size/too big/wrong panel screw layout.

I could put it in the rack, but where?
They are fairly full...5 racks and no space!

The ideal thing would be a nice cabinet of the right size,
something around 8 inches high and 11 inches deep.

Perhaps I should build separate receivers, one for 80,
one for 40 meters that powers up with each transmitter...
the pair of 813,s on 80, the 812 push pull rig for 40...


Boy, do I need some good ham fests!

Brett
N2DTS


 
> 
> Hey I will trade you a 12SA7 for a good 6K7 metal OK.  Send address.
>   Russ Dworakowski   4112 Lake Pleasant Rd.  Erie,  PA  16504.
>