XV144 - power out with no drive

[Stewart GM4AFF]

I have an intermittent problem with my XV144 (driven by a K3). On transmit I
can see power output on the LEDs (3 greens) even when there is no audio
input and the transverter is getting quite hot. Stations tell me my signal
sounds fine with no background noise. So it's generating RF somewhere else!

 

Also, more seriously, occasionally, when I return to receive after
transmitting, the transverter LEDs all illuminate, I lose receive
sensitivity almost completely, although I can still barely hear louder
signals. The transverter won't transmit unless I switch off and on the K3
and the XV144. This occurs more often as the transverter heats up.

 

I can't tell whether the first problem relates to the second or vice versa.
The second problem was the first to occur and happened on a previous XV144 I
owned, so it's not just a one-off.

 

Any ideas or suggestions?

 

Thanks!

Stewart

GM4AFF

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[Don Wilhelm-4]

Stewart,

What input level do you have the XV144 set for?  The 1mW level from the
KXV3 or the high power input from the K3 ANT1 or ANT2 jacks?
It is important that I know before I can venture a reasonable guess.

Are you using the Elecraft transverter cable to operate the XV144, or do
you have it configured for non-Elecraft and keying it with the PTT line
(you should have one or the other, but not both).  See the XVnnn Owner's
Manual.


One thing you can do is see if the XV144 is staying in transmit when it
should be switching back to receive.  When in receive, what is the
voltage at the cathode of D4 - this is the 12T signal and should be zero
during receive.

The "all flashing LEDs" condition is an indication of an overload
condition or getting RF input while the XV144 is still in receive. If
you are using the 1 mW RF input, it should never trigger that condition.
There are some XVnnn transverters that falsely detect an overload
condition.  That is due to noise on the COR detection line.  An easy
cure for that is to remove the front panel metalwork and solder a 0.1uf
capacitor between the collector and emitter of Front Panel Q7.  It can
easily be added to the solder side of Q7 without removing the front
panel board.

73,
Don W3FPR

On 12/14/2014 9:52 AM, Stewart GM4AFF wrote:

> I have an intermittent problem with my XV144 (driven by a K3). On transmit I
> can see power output on the LEDs (3 greens) even when there is no audio
> input and the transverter is getting quite hot. Stations tell me my signal
> sounds fine with no background noise. So it's generating RF somewhere else!
>
>  
>
> Also, more seriously, occasionally, when I return to receive after
> transmitting, the transverter LEDs all illuminate, I lose receive
> sensitivity almost completely, although I can still barely hear louder
> signals. The transverter won't transmit unless I switch off and on the K3
> and the XV144. This occurs more often as the transverter heats up.
>
>

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[Stewart GM4AFF]

Hi Don,
Input set to 1mW and using a K3 with a proper cable. When I switch back to
receive the XV144 always switches back to receive - like I said, I can still
hear louder stations. This doesn't mean that something on the board isn't
continuing to emit some kind of RF though.
The LEDs don't flash, they just illuminate and stay that way until I switch
off the 12v DC power.
I received another reply off-list from someone with a similar problem who
suggested contacting Elecraft for a fix.
73
Stewart

-----Original Message-----
From: Don Wilhelm [mailto:[hidden email]]
Sent: 14 December 2014 19:20
To: Stewart GM4AFF; [hidden email]
Subject: Re: [Elecraft] XV144 - power out with no drive

Stewart,

What input level do you have the XV144 set for?  The 1mW level from the
KXV3 or the high power input from the K3 ANT1 or ANT2 jacks?
It is important that I know before I can venture a reasonable guess.

Are you using the Elecraft transverter cable to operate the XV144, or do you
have it configured for non-Elecraft and keying it with the PTT line (you
should have one or the other, but not both).  See the XVnnn Owner's Manual.


One thing you can do is see if the XV144 is staying in transmit when it
should be switching back to receive.  When in receive, what is the voltage
at the cathode of D4 - this is the 12T signal and should be zero during
receive.

The "all flashing LEDs" condition is an indication of an overload condition
or getting RF input while the XV144 is still in receive. If you are using
the 1 mW RF input, it should never trigger that condition.
There are some XVnnn transverters that falsely detect an overload condition.
That is due to noise on the COR detection line.  An easy cure for that is to
remove the front panel metalwork and solder a 0.1uf capacitor between the
collector and emitter of Front Panel Q7.  It can easily be added to the
solder side of Q7 without removing the front panel board.

73,
Don W3FPR

On 12/14/2014 9:52 AM, Stewart GM4AFF wrote:
> I have an intermittent problem with my XV144 (driven by a K3). On
> transmit I can see power output on the LEDs (3 greens) even when there
> is no audio input and the transverter is getting quite hot. Stations
> tell me my signal sounds fine with no background noise. So it's generating
RF somewhere else!

>
>  
>
> Also, more seriously, occasionally, when I return to receive after
> transmitting, the transverter LEDs all illuminate, I lose receive
> sensitivity almost completely, although I can still barely hear louder
> signals. The transverter won't transmit unless I switch off and on the
> K3 and the XV144. This occurs more often as the transverter heats up.
>
>

-----
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[David Pratt]

Magic! I have just read your advice to Stewart GM4AFF and recognised a
phenomenon I have been getting with my XV144 for years. I had assumed
that the flashing LEDs were due to my fault in overdriving.

I have just added a 0.1 across E & C of Q7 and that has cured the
problem.  I must now do the same with my XV70.

Am I to assume that this mod has now been incorporated in new XV---
kits?

I am ever thankful to you, Don, for your valuable contribution to the
reflector.

73 de David G4DMP

In a recent message, Don Wilhelm <[hidden email]> writes
>There are some XVnnn transverters that falsely detect an overload
>condition.  That is due to noise on the COR detection line.  An easy
>cure for that is to remove the front panel metalwork and solder a 0.1uf
>capacitor between the collector and emitter of Front Panel Q7.  It can
>easily be added to the solder side of Q7 without removing the front
>panel board.

--
 + - - - - - - - - - - - - - - - - +
 | David M Pratt, Kippax, Leeds.   |
 | Website: http://www.g4dmp.co.uk |
 + - - - - - - - - - - - - - - - - +

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[g3ymc]

Not in my XV50 built a couple of months ago.... Note that there is
already a 0.01uF across the source of the CO line, C71 on the RF board
(the signal is confusingly called OD on that board).

I did see the flashing lights once while I was aligning it but have not
used the transverter in vengeance yet so time will tell whether I have
this issue.

73 Dave G3YMC

On 15 Dec 2014 at 9:58, David G4DMP wrote:

> Magic! I have just read your advice to Stewart GM4AFF and recognised a
> phenomenon I have been getting with my XV144 for years. I had assumed
> that the flashing LEDs were due to my fault in overdriving.
>
> I have just added a 0.1 across E & C of Q7 and that has cured the
> problem.  I must now do the same with my XV70.
>
> Am I to assume that this mod has now been incorporated in new XV---
> kits?
>

http://davesergeant.com

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[Don Wilhelm-4]

David,

To answer your question, no it has not been incorporated on the XV series.

Some transverters are just fine without it, but some others show that
problem behavior.
I usually add it to any XV transverter that I service, and I would
encourage any owner to do the same.  It simply filters any noise off
that signal line whose only component should be DC.

73,
Don W3FPR

On 12/15/2014 4:58 AM, David G4DMP wrote:

> Magic! I have just read your advice to Stewart GM4AFF and recognised a
> phenomenon I have been getting with my XV144 for years. I had assumed
> that the flashing LEDs were due to my fault in overdriving.
>
> I have just added a 0.1 across E & C of Q7 and that has cured the
> problem.  I must now do the same with my XV70.
>
> Am I to assume that this mod has now been incorporated in new XV---
> kits?
>
> I am ever thankful to you, Don, for your valuable contribution to the
> reflector.
>
> 73 de David G4DMP
>
> In a recent message, Don Wilhelm <[hidden email]> writes
>> There are some XVnnn transverters that falsely detect an overload
>> condition.  That is due to noise on the COR detection line.  An easy
>> cure for that is to remove the front panel metalwork and solder a 0.1uf
>> capacitor between the collector and emitter of Front Panel Q7.  It can
>> easily be added to the solder side of Q7 without removing the front
>> panel board.

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