RE: [drakelist] TR-4 receive squeal/oscillation

[Chuck Wyatt]

"Chuck Wyatt" <[EMAIL PROTECTED]> made an utterence to the drakelist gang
--
Found it.  Loose tube.  I guess it got unseated during shipping.  Sorry
for the bother!

Enjoying the rig now!!

73,

Chuck
KB5GC

-Original Message-
From: Garey Barrell [mailto:[EMAIL PROTECTED] 
Sent: Friday, April 08, 2005 11:46 AM
To: [EMAIL PROTECTED]
Cc: drakelist@www.zerobeat.net
Subject: Re: [drakelist] TR-4 receive squeal/oscillation


Chuck -

Sounds like an oscillation in the RF or IF stages.   This sort of thing 
is almost always the result of dried out electrolytic capacitors in the 
B+ decoupling.

The operation and function of the AC-3 and AC-4 are identical.

Since it worked with HIS power supply (we think?) I would first suspect 
the +250V electrolytics in your supply.  The caps in the bias supply 
could also be questioned since it is used extensively in the AGC 
circuitry.  It's easiest to just shunt the existing caps with whatever 
caps you have that are at least as much capacity and at least as high a 
voltage as the existing caps, leaving the existing ones in place.   When

you find the one(s) that fix the problem, remove the old one and replace

with an appropriate sub.  Never leave an old capacitor in circuit as a 
permanent repair.

There is also an electrolytic inside the TR-4, C135 I think, that 
"might" be down, but since it allegedly worked with another supply, I'd 
start there.

Let us know what you find!

73, Garey - K4OAH
Atlanta

Drake C-Line Service Manual
<http://hr99.home.mindspring.com/R-4C_Servicez/>



Chuck Wyatt wrote:

> This may be the same kind of issue as Larry had.  I just bought a
> TR-4, lights up, and I do get power out.  However, on receive, if 
> I open up the RF gain up past the half-way point, I get a loud squeal 
> from the speaker which puts the S-Units at 40 db over.  I can hear 
> signals underneath, so otherwise the receiver is functioning. Seems 
> unrelated to the kind of speaker I've got plugged into it.
>  
> Thanks for any suggestions.  I contacted the seller who said that it
> worked fine with the AC-3 powersupply, and wondered if the AC-4 (which

> I have) has the same pin-outs?
>  
> Chuck
> KB5GC
>
>




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Re: [drakelist] TR-4 receive squeal/oscillation

[Garey Barrell]

Garey Barrell <[EMAIL PROTECTED]> made an utterence to the drakelist gang
--
Chuck -
Sounds like an oscillation in the RF or IF stages.   This sort of thing 
is almost always the result of dried out electrolytic capacitors in the 
B+ decoupling.

The operation and function of the AC-3 and AC-4 are identical.
Since it worked with HIS power supply (we think?) I would first suspect 
the +250V electrolytics in your supply.  The caps in the bias supply 
could also be questioned since it is used extensively in the AGC 
circuitry.  It's easiest to just shunt the existing caps with whatever 
caps you have that are at least as much capacity and at least as high a 
voltage as the existing caps, leaving the existing ones in place.   When 
you find the one(s) that fix the problem, remove the old one and replace 
with an appropriate sub.  Never leave an old capacitor in circuit as a 
permanent repair.

There is also an electrolytic inside the TR-4, C135 I think, that 
"might" be down, but since it allegedly worked with another supply, I'd 
start there.

Let us know what you find!
73, Garey - K4OAH
Atlanta
Drake C-Line Service Manual


Chuck Wyatt wrote:
This may be the same kind of issue as Larry had.  I just bought a 
TR-4, lights up, and I do get power out.  However, on receive, if 
I open up the RF gain up past the half-way point, I get a loud squeal 
from the speaker which puts the S-Units at 40 db over.  I can hear 
signals underneath, so otherwise the receiver is functioning. Seems 
unrelated to the kind of speaker I've got plugged into it.
 
Thanks for any suggestions.  I contacted the seller who said that it 
worked fine with the AC-3 powersupply, and wondered if the AC-4 (which 
I have) has the same pin-outs?
 
Chuck
KB5GC


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RE: [drakelist] TR-4 receive squeal/oscillation

[Chuck Wyatt]

Title: Message



I will 
check that Marty!  The seller suggested that I should turn all the VOX pots 
down, and make sure the switch is on Transceive and not Receive.  It was on 
Receive originally when I switched it on and the squeal/tone was there.  
Also switching it to CW made a sidetone like sound, so perhaps it is related to 
the VOX circuit.  I'll check it out when I get home and let you 
know.
 
Otherwise, it's such a nice classic looking rig!  Has that wonderful 
"old" rig smell.
 
-Chuck

  
  -Original Message-From: Allen (Marty) 
  Martin [mailto:[EMAIL PROTECTED] Sent: Friday, April 08, 2005 
  10:17 AMTo: [EMAIL PROTECTED]Subject: Re: [drakelist] 
  TR-4 receive squeal/oscillation
  Are you keying the transmitter via the vox 
  circuit when you turn up the audio gain? 
   
  Marty
   
  
- Original Message - 
From: 
Chuck Wyatt 

To: drakelist@www.zerobeat.net 

Sent: Friday, April 08, 2005 5:51 
AM
Subject: [drakelist] TR-4 receive 
squeal/oscillation


This may be 
the same kind of issue as Larry had.  I just bought a TR-4, lights up, 
and I do get power out.  However, on receive, if I open up the RF gain up past the half-way 
point, I get a loud squeal from the speaker which puts the S-Units at 40 db 
over.  I can hear signals underneath, so otherwise the receiver is 
functioning. Seems unrelated to the kind of speaker I've got plugged 
into it.
 
Thanks for 
any suggestions.  I contacted the seller who said that it 
worked fine with the AC-3 
powersupply, and wondered if the AC-4 (which I have) has the same 
pin-outs?
 
Chuck
KB5GC

  
  -Original Message-From: 
  [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] 
  On Behalf Of Larry GroomSent: Thursday, April 07, 2005 
  8:07 PMTo: drakelist@www.zerobeat.netSubject: 
  [drakelist] Weak and distorted audio
    Hello 
  gang, just bought a TR-4C that's is great condition and works well but the 
  audio seems weak and distorts
  when the 
  volume control is increased past half way, it seems "punchless". It sounds 
  fine using headphones pluged
  into the 
  ehadphone jack. I've tried two different MS-4 with the same results. Is it 
  possible that theaudio output is
  weak for the 
  speaker but strong enuf for the headphones? Any other 
  ideas?
   
  Thanks in 
  advance..
   Larry



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