Can someone explain the Sherwood roofing filter mods? Can you select the
bandwidth of the filter? Is the CF-2K/8 the only filter available?
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Michael,
I have rebuilt several supplies and have used both the Harbach Electronics
board and the HeathkitShop board; only difference is that the latter has space
for equalizing resistors for the diodes whereas the former you have to add them
directly to the diodes themselves should you choose
Hi All,
OK, I'm going fishing here. Does anyone on list have a 6 kHz AM filter for
the R4C you would consider selling? If so, I'd like to visit with you about
it.
Thanks much and very 73.
Kevin :)
Amateur Radio: K7RX
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Hi Michael,
Sorry to hear of your problem with the L-4PS burning. To answer your
question, I did the Heathkit Shop L-4PS upgrade to my L-4B just about a year
ago and I highly recommend it. It replaces all of the L-4PS components
except the transformer, breakers and the 50K 50W bleeder resistors. I
Just as I have heard all the stories of power supplies being destroyed, my
L4B power supply did just that. Turned on the amplifier just like I always
have heard a big bang and looking to find the noise and then saw the fire.
Turned off the L4B and removed the 220 volt plug from the wall just in tim
- Original Message -
From: "Garey Barrell"
To:
Sent: Wednesday, February 23, 2011 5:32 PM
Subject: Re: [Drakelist] Drakelist Digest, Crystal calabrator Gone south?
My crystal was bad when received 2B with calibrator installed. Put crystal
for
for one of the bands into it to confirm
Paul -
Good idea!! If the receiver goes 'dead' in the CALIBRATE position, find
that shorting plug! (Or connect the cable to the MUTE on receiver and
transmitter.)
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
ph...@aol.com wrote
Fred -
Most likely it's a power supply problem. If you have a DMM or VOM it
would be easy to check.
There's a diode and a couple of electrolytic caps that ONLY power the
Calibrator's Buffer and Divider stages.
D16, R158, R157, C190 and C192. It's a half-wave rectifier from the
filament s
Fred,
Before you try to "fix" the calibrator, make sure it truly is not
working and it isn't just a matter of your not having a "shorting" plug in the
MUTE jack. If you don't put a shorted RCA plug in that jack the CAL won't
work.
73/Paul, K4MSG
In a message dated 2/23/2011 6
Crystal calibrator on the Drake B line twins. Is this an easy fix or
expensive fix or is it something I could locate and fix myself? What equipment
is required to locate and repair this item. Looking at he schematic it could
be a transistor or and IC in the receiver. Any thoughts?
73 de Fr
Hi Garey,
My first reaction is, "Wow!" I was hoping there was already a muting
circuit, as with the TR7-R7 pairing, but in that case I doubt anyone
would use the TR7 as the receiver. I'll get my Service Manual out
and go from there.
Thanks much!
VY 73,
Tony
K4KYO
At 01:28 PM 2/23/2011, G
Tony -
I'm not aware of any external 'Standby' control for the TR-7 receiver.
A quick look at the schematic shows that the AF OUTPUT chip has it's own
+13.6 VDC source on Pin 30 of the 2nd IF/AF board. There is a 22 uF cap
on the line, so the cut off 'might' be a little slow, but it looks li
Hi guys,
This morning during my vintage AM net, my antenna changeover relay
decided to quit on me, so I switched on my TR7 to use as a
receiver. As there's no standby mode, before transmitting (100
watts) I turned the RF and AF gain all the way down and manually
switched the antenna to the T
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