Thanks to all who replied with suggestions on the replacement mixer, etc.
I will probably go with the SBL-1MH+ if I can amend my order from RF parts.
How this damage was done involved using the wattmeter in a Kenwood antenna
tuner and a separate dummy load to check for TX output.
When I saw no indication on the meter when checking the TR-7, I wanted to
confirm that the meter was at working, and connected it to a known-good
transceiver.
After swapping cables a few times, the transceiver output was inadvertently
connected to the TR-7, and the rest, as they say, is history.
Will also check the PIN diodes and other components between the antenna input
and upconverter later this weekend.
73
Charles
K5QED
----- Original Message -----
From: Ron Baker
To: 'Charles Kaross' ; [email protected]
Sent: Friday, April 23, 2010 09:58
Subject: RE: [Drakelist] TR-7 RX blown due to lapse of sanity
Charles, The Mini-Circuits part number SBL-1MH+ is a direct replacement to
the CM1 in the Drake TR7. I have replaced several of those double balanced
mixer modules and that one works perfectly.
Ron / WB4HFN
------------------------------------------------------------------------------
From: [email protected] [mailto:[email protected]]
On Behalf Of Charles Kaross
Sent: Friday, April 23, 2010 7:20 AM
To: [email protected]
Subject: [Drakelist] TR-7 RX blown due to lapse of sanity
In a moment of carelessness, I inadvertently transmitted into the RX input of
my recently acquired TR-7 while testing the transmitter output last week.
OK - I can hear the laughter now, and it is well deserved!
So far I have determined:
The rig had zero (or near zero) RF output when purchased - I will move this
problem to the bottom of the list.
The diodes in the CM-1 mixer module on the upconverter board are shorted -
hopefully this the limit of the damage caused by my negligence.
I cut open the CM-1 module with a Dremel, and the diode ring is a discrete
part, encapuslated in what appears to be a ferrite bead, so the module will
have to be replaced.
I have ordered a MiniCircuits SRA-1 mixer from RF Parts, which I hope will be
a direct replacement for the CM-1.
I will post the results of my efforts to repair this rig to the list.
Any comments, questions and or razzing is now being accepted ....
Thanks,
Charles
K5QED
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