Steve -
Yes, the 150 ohm resistor is a reasonable substitute for the nominal filter loss. You could just
jumper it with a piece of wire and subtract about six dB!
The filter is 1k ohm in and out impedance. When you get it out and have the 150 ohm resistor in
there, plug it into one of the filter sockets on the back panel and see if it works there? Does it
have the correct passband shape, just attenuated?
I've never seen one of these go bad, but there's a first time for everything! My bet is on the
switch(es) or a shorted cable.
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>
Steve Wedge wrote:
'Twas looking at it this evening, and this is going to take some disassembly. I wish it had the
same form factor as the optional filters so I could try moving/swapping it.
Am I correct in assuming that I could jumper this filter with a 150 ohm resistor to check the
signal level? I'm just wanting to be sure that the filter really is bad before going through the
time and expense of replacing it (after all, it could be a switch contact). The case is making
good contact with the chassis and GND.
Steve Wedge, W1ES/4
Live free or die: Death is not the worst of evils.
John Stark.
All my computers have my signature with various pearls of wisdom appended
thereto.
--------------------------------------------------
From: "Garey Barrell" <k4...@mindspring.com>
Sent: Tuesday, January 31, 2012 11:00 PM
To: <kc9...@aol.com>
Cc: <w1es1...@earthlink.net>; <drakelist@zerobeat.net>
Subject: Re: [Drakelist] R-4C 2.4 filter bad?
Lee -
No, the 2.4 kHz filter is under the chassis, along the back wall.
I know all about that 'memory' stuff! :-)
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>
kc9...@aol.com wrote:
Steve,
The 2.4 filter plugs into the back....as does the 1.5, .5 or whatever you want in those slots.
The 2.4's are pretty available.
There is a front end filter and I think it is 8khz on the chassis.
I'm going from memory here...whaich may be ok. most of the time....-:)
73,
Lee
-----Original Message-----
From: Steve Wedge <w1es1...@earthlink.net>
To: Drake List <drakelist@zerobeat.net>
Sent: Tue, Jan 31, 2012 7:11 pm
Subject: [Drakelist] R-4C 2.4 filter bad?
I haven't dug into this receiver yet, but it seems to me that the 2.4 kHz SSB filter is bad.
R-4C, late serial number.
* Using the S-meter, the signal strength of the calibrator is lower in 2.4 by 10 dB, than the
reading in both 1.5 and .5.
* The decrease in gain is solid and not intermittent. Rocking the MODE switch doesn't reveal
any changes.
* It's also a noticeable loss listening on-the-air.
I see what appears to be the filter on the top side of the chassis, under where the two carrier
oscillator crystals are. Has anyone had any grounding issues with this filter that have fixed a
similar problem? I figure if there's a bad ground, it could affect the insertion loss of this
filter.
If it's bad, then comes the pain of finding a replacement. If anyone has an extra one for sale,
let me know.
Steve Wedge, W1ES/4
_______________________________________________
Drakelist mailing list
Drakelist@zerobeat.net
http://mailman.zerobeat.net/mailman/listinfo/drakelist
