[drakelist] Microphone for TR4C

[Ian MacQuillan]

Title: Message



I am new to using 
newsgroups and my previous question was not complete - 
apologies

  What is the name 
  and model of the microphone that came with the TR4C?
  What is the 
  impedance value of that microphone?
Thanks

73, de ZS5IAN
Member of HARC 
Member of SARL

(No trees were harmed in the production of this message, however a large 
number of electrons were temporarily
inconvenienced.) 

[drakelist] Replacement of TR-7 Analogy Scale-Lamp

[K3wy]

Hi Guys:
Can nowhere find how to replace this lamp over the analogy scale.
Any idea?
Thanks & 73's, 
Herb, DJ3OE & K3WY
 

Re: [drakelist] AC-4 Cap values

[Ron]

Ron <[EMAIL PROTECTED]> made an utterence to the drakelist gang
--
These NTC Thermistors are often sold as "Inrush Current Limiters"  They are 
made by Keystone Electronics, come in a variety of values, and (I think) 
can still be bought from Digikey.  I bought a selection of values from them 
years ago when I built a 500W 6550 based audio amp.  It had 8000 MF of 
capacitance in the PS, and would blow a 25 amp fuse every other time you 
turned it on.  The inrush limiter solved that problem perfectly: 12 years 
later I still haven't popped a fuse.


At 06:49 PM 3/3/2005, Carl Strode wrote:
Carl Strode <[EMAIL PROTECTED]> made an utterence to the drakelist gang
--
What I may do is to install a NTC (Negative Temperature Coefficient) high 
current thermistor in series with the incoming AC line. These are really 
cool devices. At room temperature (25C/ 77F) they exhibit a high 
resistance, as they self heat, the resistance drops. The one I will try 
starts out at 47 ohms, then slowly drops to less than one ohm in less than 
a second. Steady state current rating is 4 amps.

Perfect for a surge limiter.
Gerry wrote:
Unfortunately, inserting series resistors in the B+ leads will, depending 
on the value, adversely affect regulation. It may work fine for static 
loads such as the +250 supply but is not advisable for HV supplies with 
dynamic loads. Years ago I tried a home brew power supply constructed 
with mil surplus components. What I found is that choke input supplies 
need a critical value resistive load to maintain the voltage below 
allowable limits. With no load on the +650 volts, it went almost to the 
rating of the filter caps which I believe was 800 volts. Trying another 
approach with a capacitive input filter and a choke meant I had to find 
another transformer. When I did, the 50 Ohms resistance of the choke 
became somewhat of a problem which all made sense later. At 450 mils, 
that would be a 22.5 volt drop on top of whatever the drop was in the 
first place. The thump comes from the transformer and is loudest when 
power is switched on at the peak of the primary AC cycle. Sometimes you 
can hit it just right. When I built my Heathkit SB-1000 linear, there was 
an alignment procedure which called for removing the screws and sliding 
the case back about an inch or so. This was done per the assembly 
instructions to align the input coils. When I turned on the amp for the 
first time, there was a loud KABAM! After changing my underwear, it 
became obvious what happened: there was a surge at turn on and the steel 
cover acted like a sounding board. Nothing bad happened to the amp, it 
was just one of those things that makes you tremble whenever you reach 
for the ON switch. This brings up another point about the need for 
slow-start on such devices. I don't use the linear often but it is on my 
to-do list.

-Original Message-
*From:* [EMAIL PROTECTED] 
[mailto:[EMAIL PROTECTED] *On Behalf Of [EMAIL PROTECTED]
*Sent:* Thursday, March 03, 2005 2:54 AM
*To:* drakelist@www.zerobeat.net
*Subject:* Re: [drakelist] AC-4 Cap values

Carl,
Now might be a good time to review some slow-start feature design reviews,
looking forward to incorporating one into the turn-on function of the power
supply. When you have a "thump" from turning on a power supply, it
generally is indicative of too great of a surge current going into the filter
capacitors and stressing them unnecessarily. It doesn't help the rectifiers,
either. Also, I'm not sure that it is a "leaky" capacitor that causes the
"thump" you heard at power supply turn-onI've always been led to
believe that the "thump" was from the large flow of current into an
uncharged capacitor, although I've never had it proven to me that this
was the actual cause.
You could, however, benefit the power supply considerably, by inserting a
resistor of the proper resistance and wattage, into the 650 volt output,
between D2 and the connection to R1. This would also serve to bring your
650 volt HV (now approx. 700 volts, as you indicated) back down nearer to
the correct 650 volt value.
Your could also do the similar action with a resistor added between D5 and
the connection to C3, and also reduce the 290 volts down to the original
design value of 250 volts.
Possibly, the original design of this power was slighted somewhat, by not
including a choke in each of the two points I noted above. That would
have produced a significant reduction in the capacitor surge current at
turn-on. Chokes would also have been more effective in reducing the
ripple you originally saw on the outputs.
I'm naturally assuming, of course, that you do intend to reduce power
supply outputs down to their specified voltage levels.
I haven't intended to sound critical of your modification efforts here, Carl.
Moreso, I am critical that Drake didn't put choke filtered su

Re: [drakelist] Microphone for TR4C

[Don and Diana Cunningham]

Title: Message



The microphone sold at the time of the TR4 was the 
Drake 7075.  It was high impedance.  A lot of us use the Shure 444 and 
444D with our 4 Line gear.
73,
Don, WB5HAK

  - Original Message - 
  From: 
  Ian MacQuillan 
  
  To: drakelist@www.zerobeat.net 
  Sent: Friday, March 04, 2005 2:05 
AM
  Subject: [drakelist] Microphone for 
  TR4C
  
  I am new to using 
  newsgroups and my previous question was not complete - 
  apologies
  
What is the name 
and model of the microphone that came with the TR4C? 
What is the 
impedance value of that microphone?
  Thanks
  
  73, de ZS5IAN
  Member of HARC 
  Member of SARL
  
  (No trees were harmed in the production of this message, however a large 
  number of electrons were temporarily
  inconvenienced.) 

Re: [drakelist] Microphone for TR4C

[Garey Barrell]

Garey Barrell <[EMAIL PROTECTED]> made an utterence to the drakelist gang
--
No microphone came with the TR-4C.
The Shure 444 is a reasonable color and style match.  Two tone gray.
Drake sold the Model 1525 mobile "touch-tone" mike later, and the 7077 
desk mike for the TR-5/7 series.

The TR-4C was designed to use a Hi-Z microphone.   The Astatic D-104 
works well, as will the Electrovoice 664.  The audio stages are designed 
for a wide range, flat frequency response microphone, as the transmitter 
has it's own frequency shaping.

Bottom line is just about any Hi-Z (crystal, ceramic or dynamic 
w/transformer) microphone will work.  How good a particular mike sounds 
is primarily a function of your voice characteristics.

73, Garey - K4OAH
Atlanta
Drake C-Line Service Manual


Ian MacQuillan wrote:
I am new to using newsgroups and my previous question was not complete 
- apologies

   1. What is the name and model of the _microphone_ that came with
  the TR4C?
   2. What is the impedance value of that microphone?
Thanks
73, de ZS5IAN
Member of HARC
Member of SARL
(No trees were harmed in the production of this message, however a 
large number of electrons were temporarily

inconvenienced.)
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Re: [drakelist] Replacement of TR-7 Analogy Scale-Lamp

[Garey Barrell]

Garey Barrell <[EMAIL PROTECTED]> made an utterence to the drakelist gang
--
Herb -
You have to remove the DR-7 Counter board, the large board on top.  The 
bulb is a #53.

Step by step instructions have been posted several times and are in the 
Archives for this list.  If you can't find them I can send them to you 
off list.

73, Garey - K4OAH
Atlanta
Drake C-Line Service Manual


[EMAIL PROTECTED] wrote:
Hi Guys:
Can nowhere find how to replace this lamp over the analogy scale.
Any idea?
Thanks & 73's,
Herb, DJ3OE & K3WY
 
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[drakelist] AC4R upgrade; Happy Customer!

[john_k7fd]

<[EMAIL PROTECTED]> made an utterence to the drakelist gang
--

Just a quick note to say the Mike Bryce WB8VGE Drake AC-4 power supply upgrade 
works great! I actually ended up sending my supply to Mike and having all the 
work done in his shop; the turnaround time was fast (a day in his shop plus 
shipping time) and his workmanship excellent. 

73 John K7FD

AC4R info: http://www.theheathkitshop.com/drakeac4rreplace.html

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RE: [drakelist] Replacement of TR-7 Analogy Scale-Lamp

[Dick Harms PA2DW]

"Dick Harms PA2DW" <[EMAIL PROTECTED]> made an utterence to the drakelist gang
--
Hi Herb,

Take my advise, replace those bulbs by one of those powerfull white LED's.
Flatten the front of the LED with a file, in order to "diffuse" the light a
bit.
Advantage is obviously that you no longer have to go through the procedure
of removing the DR7 every time that the bulb goes flying with the angels.
But also the light of the LED makes that the display of scale and S-meter
becomes very bright blue! Very nice indeed.

Best 73, Dick/PA2DW

-Oorspronkelijk bericht-
Van: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] Garey Barrell
Verzonden: vrijdag 4 maart 2005 16:21
Aan: [EMAIL PROTECTED]
CC: drakelist@www.zerobeat.net
Onderwerp: Re: [drakelist] Replacement of TR-7 Analogy Scale-Lamp



Garey Barrell <[EMAIL PROTECTED]> made an utterence to the drakelist gang
--
Herb -

You have to remove the DR-7 Counter board, the large board on top.  The
bulb is a #53.

Step by step instructions have been posted several times and are in the
Archives for this list.  If you can't find them I can send them to you
off list.

73, Garey - K4OAH
Atlanta

Drake C-Line Service Manual




[EMAIL PROTECTED] wrote:

> Hi Guys:
> Can nowhere find how to replace this lamp over the analogy scale.
> Any idea?
> Thanks & 73's,
> Herb, DJ3OE & K3WY
>

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