OK, I fixed up the RF choke in my Eico 720, cleaned up a few things,
put a "new" 6146 in (taking out the 6146B that someone else had put
in),
etc.

The oscillator/multiplier seems to be working fine. I put in a 40M
crystal, can peak up grid drive just fine. Set it to 20M, and get
14 MHz out of the driver. Switch to 21 MHz, the driver works as a
tripler.
So I think all the tuned circuits there are working fine.

Plug in a 75W light bulb, can load it up just fine. Dip in plate
current
exactly matches peak in power out. That's great.

But while I'm tuning up into the dummy load, the note as monitored on
a nearby receiver sounds awful. Yeah, there's a carrier there, but I
hear
obvious 60Hz hum and what I think is 60Hz FM. Some chirp, but not too
awful.

I've already replaced the electrolytics in the power supply (40uF 450V
units replaced with new 47uF 450V units). Do all Eico 720's sound this
bad? Or is it something else? Maybe the crystal can't take the power
in the oscillator (the 6CL6 oscillator really is putting out nearly 70V
P-P on 40M)? Something wrong with the clamper? Hum on screen
voltages?

Next thing I'm gonna try is putting a known clean crystal oscillator
into
the Eico 720 and see how it sounds.

All the voltages in my 720 seem to be maybe 10 to 20 percent high. Is
this better electrolytics, higher AC line voltage, or is it indicative
of something else?

Tim (KA0BTD).

wrote:


But while I'm tuning up into the dummy load, the note as monitored on
a nearby receiver sounds awful. Yeah, there's a carrier there, but I
hear
obvious 60Hz hum and what I think is 60Hz FM. Some chirp, but not too
awful.

Are you sure the rcvr is not overloading?

-Bill

"-ex-" wrote in message
...
wrote:


But while I'm tuning up into the dummy load, the note as monitored on
a nearby receiver sounds awful. Yeah, there's a carrier there, but I
hear
obvious 60Hz hum and what I think is 60Hz FM. Some chirp, but not too
awful.

Are you sure the rcvr is not overloading?

-Bill

My answer also- maske sure the problem is not in the RX before tearing into
the 720.

Dale W4OP

All the voltages in my 720 seem to be maybe 10 to 20 percent high. Is
this better electrolytics, higher AC line voltage, or is it indicative
of something else?

Tim (KA0BTD).

Tim - Turn the RF gain all the way down on your receiver, and the
audio gain all the way up. Key the transmitter, and slowly bring up
the RF gain. Bet it sounds better...

JOE