[drakelist] Microphone for TR4C

[Ian MacQuillan]

Title: Message



I have recently got 
a Drake TR4C transceiver but without the microphone. It functions well on CW. My 
questions are

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

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] AC-4 Cap values

[Jim Shorney]

"Jim Shorney" <[EMAIL PROTECTED]> made an utterence to the drakelist gang
--
On Thu, 03 Mar 2005 15:49:52 -0800, Carl Strode wrote:

>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.

I salvage these from dead PC power supplies and monitors. They're
usually just about right for an AC4. Here's a good article on inrush
limiting, courtesy of the R-390(a) crowd:

http://209.35.120.129/Pearls/inrush-current-FAQ.pdf



-- 
Jim Shorney  -->.<--Put complaints in this box
jshorney (at) inebraska.com
nu0c (at) amsat.org
Ham Radio NU0C
Lincoln, NE, USA
EN10ps
http://incolor.inetnebr.com/jshorney/

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Re: [drakelist] AC-4 Cap values

[Carl Strode]

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 supplies in 
this

equipment. I would sure have liked my T-4XB/R-4B's AC-4 to have been
choke filtered. (Guess they figured the cost of the choke, a place to 
put it,

and also a slight change in the secondary output winding in the power
transformer secondaries would cost too much to add into the equipment
price.
Anyhow, and Meanwhile, back at the Ranch (as "they" say, somewhere)
keep up the good work, and keep us posted.
Bill Flowers K5VKL
___
On Wed, 02 Mar 2005 20:37:21 -0800 Carl Strode <[EMAIL PROTECTED] 
> writes:
Carl Strode <[EMAIL PROTECTED] > made 
an utterence to the
d

RE: [drakelist] AC-4 Cap values

[Gerry]

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 supplies in this





equipment.   I would sure have liked my
T-4XB/R-4B's AC-4 to have been





choke filtered.   (Guess they figured the
cost of the choke, a place to put it,





and also a slight change in the secondary output
winding in the power





transformer secondaries would cost too much to add
into the equipment





price.





 





Anyhow, and Meanwhile, back at the Ranch
(as "they" say, somewhere)





keep up the good work, and keep us posted.





 





Bill Flowers   K5VKL   











___





 





On Wed, 02 Mar 2005 20:37:21 -0800 Carl Strode <[EMAIL PROTECTED]> writes:
> 
> Carl Strode <[EMAIL PROTECTED]>
made an utterence to the 
> drakelist gang
> --
> I have completed re-capping the AC-4.
> 
> After looking at the actual caps installed, and comparing it to my 
> supply of modern electrolytics, I have replaced the 40 mfd caps 
> (shown  as 40 mfd on most schematics) with 33 mfd.
> 
> The HV filter caps were replaced with 150 mfd 450 volt units.  ( I 
> had a  bunch of these 

[drakelist] TR-3 Schematic

[Jim Theisen]

Hi
I am starting to revive the TR-3 I purchased. I 
have cleaned the unit. Fixed the PTO gears and so forth. I am now in the process 
of checking the resistance checks from a chart in manual I downloaded from BAMA. 
V-17 and V-20 do not match the chart. It shows some resistance where the tube 
are not even wired to anything. I am new to this. Is the schematic that I 
am using correct or is there one more specific to my unit. It is Serial N#r 
1363. Any help would be appreciated.
 
Thanks
 
Jim WB8REH
Internal Virus Database is out-of-date.
Checked by AVG Anti-Virus.
Version: 7.0.300 / Virus Database: 265.8.6 - Release Date: 2/7/2005

[no subject]

[n . dunham]

Drake Users:
    About a month ago I purchased a TR4C which had low gain on the 15 and 10 meter band, I mentioned it here and was given some ideas of replacing certain tubes and alinement. Update on this is I have done these and the unit is now working very well. Thanks to all that inputed to my problem. However since then I have purchased an additional unit for my Drake C line.  A [R4C] receiver, it is a nice unit except that it does not work on AM,  I have cleaned all the selctor switches and made sure that the 150 resister is working ok in the AM fileter bank, and I am now down to the AM detector which is a 2N3394 or the AM detect Diode 1N270. What my question now is from all the gerues, am I on the right track or should I be looking else where..
Thanks very much for the Drake support. 
DE KA8MMI [Neil Dunham}

[drakelist] Rebuild L-4PS

[Sascha Starkloff]

Hi all!
I've got an old L-4B in my shack. Few weeks 
ago I cleaned the amp and also the power supply. I could see the old 
capacitors changing their appearance. They looked a bit dirty and also making 
some bubbles at the top and bottom covers. So I decided to rebuild the old 
pcb...
I got the capacitors at ebay - great price, and so 
little size today! All other parts came frome the local electronic-shop. Now 
there is only one pcb inside the PS. All together costs about 25 Euros (equal to 
about 30$). For that little money you can turn the old L-4PS into a "new" one. 
(Same output as the old one)
 
But be careful! 2500Volts can hurt...
 
73's Sascha

[drakelist] Drake Amplifier power supply upgrade---update

[Mike Bryce]

boys and girls..

I have aquired some low profile high voltage capacitors. With some fancy pcb layout. I believe I can get BOTH of the old drake L4 supply boards on ONE pcb.

this would drop the price down considerably. Right now, about, somewhat, close to, around, $100 for the kit...give or take a few bucks



that being said, there's not been much interest in this project..

Mike, WB8VGE
SunLight Energy Systems
The Heathkit Shop

http://www.seslogic.com
http://www.theheathkitshop.com/

WG: [drakelist] Another L-7 Question

[Graf Ulrich Com MD PD ST 2 ULM 1]

Graf Ulrich Com MD PD ST 2 ULM 1 <[EMAIL PROTECTED]> made an utterence to the 
drakelist gang
--

Hello Kevin,

whichever linear you are operating, using alc is a way to go but never the best 
way. Alc is a control system that always causes a specific time delay to react. 
Operation with high amounts of alc feedback may therefor cause a lot of 
splatter until the system has settled. So alc in general is only a good system 
to protect your setup from destruction but not to achieve a clean signal.

Best way to go: Reduce output power of the driving transceiver, feed the pa and 
increase power slowly to the wanted amount of pa output or maximum allowable 
grid current. In ssb you perform that best talking into the mic with a normal 
voice and measuring output power with a pep wattmeter. With this adjustment alc 
is superfluous and your signal alway as clean as possible. After getting used 
to the procedure it's rather simple to keep those power levels or adjustment 
values in mind for standard operation on all bands.

73 Uli, DK4SX

-Ursprüngliche Nachricht-
Von: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Im Auftrag von Kevin Nathan
Gesendet: Mittwoch, 2. März 2005 16:02
An: drakelist@zerobeat.net
Betreff: [drakelist] Another L-7 Question



"Kevin Nathan" <[EMAIL PROTECTED]> made an utterence to the drakelist gang
--
Hi All,

I will be driving my L-7, when I get it, with a Kenwood TS-480SAT, maximum of 
100 watts.  I have been advised by a couple of people that with this level of 
drive, I really don't need to worry about connecting the ALC line. I would like 
to know if there is agreement with this opinion or not among owners on this 
list.  If ALC is recommended, the manual for my 480 says the ALC input from the 
amp is -7V.  Would this be compatible with the ALC output of the L-7?

Thanks for your thoughts on both of these questions and very 73.

Kevin :)
Amateur Radio:  K7RX
Navy Marine Corps MARS:  NNN0SHS

 



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