Garey, Gary and others who have replied....
Well, in the great tradition of Ham radio, thanks to all for coming to the
rescue as Elmers. Good news that the rig is working properly and that I was
just being inept about how it is supposed to work.
Gary: I'm pretty sure (even with my shaken confidence) that it is not stuck
in transmit. However I may have screwed up the description of the Mute
cable behavior, the plate current is nil until switching to Tune, when it
behaves normally. I can now also hear the slight click of the relay that I
couldn't hear before (go figger).
Again, as I slink away in embarrassment, thanks to all for the help. And,
again, bad marks for the Drake manual!
Regards,
Rick WØRIK
-----Original Message-----
From: Garey Barrell [mailto:[email protected]]
Sent: Wednesday, February 08, 2012 7:31 AM
To: Rick Wallace
Cc: 'Drake List'
Subject: Re: [Drakelist] Receive/Transmit Relay? Mute Problem?
Rick -
What you describe is NORMAL operation......
When the receiver switch is set to ON,<surprise!> the receiver is ON!
Regardless of any other setting.
Likewise, when the receiver is set to EXT MUTE, it is capable of being muted
externally! Obviously
if you want to use the Noise Blanker or the Calibrator, you want the
receiver to be ON, so those
choices also need the ON condition. This is why a shorted plug must be
installed in the MUTE jack
on the rear panel to use the receiver as a 'standalone' unit and continue to
have access to the NB
and CAL functions.
Your #4 is confusing. You say you disconnected the _receiver_ end of the
MUTE cable, and then
describe cable resistance checks related to various _receiver_ switch
positions. If you measure
the receiver MUTE connector, it will be grounded in ON, and a negative
voltage in EXT MUTE, NB or
CAL. The transmitter MUTE connector should read shorted when the transmitter
is in standby, and
OPEN when in transmit.
The MUTE function operates as follows:
When the _transmitter_ is in RECEIVE mode, (the relay is open,) the MUTE
line in the transmitter
is grounded by a set of relay contacts. This ground is therefore applied to
the MUTE connector of
the receiver, via the MUTE cable. When the receiver MUTE jack is grounded
by this connection, the
receiver is in normal operation. IF the FUNCTION switch is set to ON, the
receiver operates
normally without regard to the MUTE jack being grounded or not.
When the transmitter is in any TRANSMIT mode, the MUTE line is 'open' (NOT
grounded) in the
transmitter. This 'open' is carried to the receiver MUTE connector by the
cable, and if the
receiver FUNCTION switch is in EXT MUTE, NB or CAL, the receiver will be
muted, and the AVC line
will go to maximum to cut off the RF/IF stages. The S-Meter WILL to full
scale.
You describe the transmitter as 'working', which is ONLY possible if the
relay has pulled in. It's
a small relay but should be quite audible. Sometimes it's masked by the
click of the switch detent.
So unless I'm misreading your question(s), it sounds like if you put the
receiver in the EXT MUTE,
NB or CAL positions that it IS being muted and the system is operating as
expected.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
<www.k4oah.com>
Rick Wallace wrote:
Hi all,
I have a Drake C-line rig that does not mute the receiver even though the
transmitter is set to
transceive. The unit has just been refurbished by one of the well known,
much admired folks who
do that kind or work so I'm sure it was in top notch working order when it
was re-boxed and sent
back to me via UPS, here on Vashon Island, WA. However, when I hooked
everything up I found a big
problem.
1. The receiver does not mute in any of the transceive modes. I get
acoustic feedback of my
voice if I transmit SSB. When I go to tune mode I get a loud tone (maybe
1,000 Khz sidetone?) in
the speaker.
2. I've double checked all the interconnecting cables and had an
experienced Ham double check my
connections as well. I've also swapped a fresh cable into the mute cable
position, as well as
each of the other cables, as a process of elimination technique.
3. If I switch the receiver Function switch to external mute or noise
blanker, the receiver
mutes. However, even though the speaker is muted, the S-meter goes all
the way over to the right
to 60 decibels if in Tune mode.
4. We disconnected the receiver end of the mute cable and measured
continuity to ground when
switching the transmitter to Tune. The mute cable is not being connected
to ground if the
receiver is simply in the On position. However, the mute cable is being
grounded if the receiver
Function switch is in the External Mute or Noise Blanker positions.
5. During all this, we hear no clicking of the transmit/receive relay.
What do you think? A faulty relay? Something upstream of the relay?
Where do I start looking?
Thnx,
Rick WØRIK
