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XV50 no output

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g3ymc

XV50 no output

My XV50, which worked fine for this summer's sporadic E season, has
suddenly gone faulty and has no output in either CW or SSB. The input
from the K2 is present, although of course 5mW is pretty hard to
measure accurately with my scope. There is also no signal at the input
of the power amplifier module, but if I connect my scope probe to C48,
at the output of the bandpass filter, and key the rig I have more or
less correct output and a good 50MHz sinewave on the scope - as soon as
I remove the probe the output disappears again. So the output module is
fine and the fault would seem to be related to the U6 buffer or the
bandpass filter. I am a bit mystified and need to sit down and work out
what is really happening.

Is there anywhere I should be looking?

73 Dave G3YMC

http://davesergeant.com

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Don Wilhelm-4

Re: XV50 no output

Dave,

Be cautious with conclusions when probing with a 'scope probe in the 50
MHz section of the XV50. The probe can pick up RF and produce false
output indications.
The fact that you can induce output by probing C48 does normally
indicate that U6 and U7 are capable of producing a signal.
Check the LO signal. If that is good, then the problem may be in the 28
MHz bandpass or the mixer.

I am puzzled by your reference to 5mW. The K2 with the K60XV has 1mW
output - was that a typo?

If you want to probe the 28 MHz IF in the XV50, you can re-plug the
transverter for up to 5 watts input and you should be able to follow the
signal path through the 28 MHz bandpass filter - all the way to the
mixer input.

If it works with the high level input, then try the low level input
again - the 1mW input removes the attenuator and adds the gain of the Q6
stage.

73.
Don W3FPR

On 11/20/2015 11:22 AM, Dave Sergeant wrote:

> My XV50, which worked fine for this summer's sporadic E season, has
> suddenly gone faulty and has no output in either CW or SSB. The input
> from the K2 is present, although of course 5mW is pretty hard to
> measure accurately with my scope. There is also no signal at the input
> of the power amplifier module, but if I connect my scope probe to C48,
> at the output of the bandpass filter, and key the rig I have more or
> less correct output and a good 50MHz sinewave on the scope - as soon as
> I remove the probe the output disappears again. So the output module is
> fine and the fault would seem to be related to the U6 buffer or the
> bandpass filter. I am a bit mystified and need to sit down and work out
> what is really happening.
>
>

g3ymc

Re: XV50 no output

Thanks Don. Having looked at it again it does actually look as if the
output from the K2 transverter socket is missing or very low. I got a
bit confused about levels (as well as making typos) and I should most
definitely be able to see the 1mW on my scope (632mV p-p). I did have
to tighten up the locknuts on the phono sockets at the K2, maybe there
is an open circuit or short circuit there as well. Will take the K2
apart again later and check, but the XV50 is probably OK.

73 Dave G3YMC

On 20 Nov 2015 at 14:28, Don Wilhelm wrote:

> Dave,
>
> Be cautious with conclusions when probing with a 'scope probe in the 50
> MHz section of the XV50. The probe can pick up RF and produce false
> output indications. The fact that you can induce output by probing C48
> does normally indicate that U6 and U7 are capable of producing a signal.
> Check the LO signal. If that is good, then the problem may be in the 28
> MHz bandpass or the mixer.
>
> I am puzzled by your reference to 5mW. The K2 with the K60XV has 1mW
> output - was that a typo?
>
> If you want to probe the 28 MHz IF in the XV50, you can re-plug the
> transverter for up to 5 watts input and you should be able to follow the
> signal path through the 28 MHz bandpass filter - all the way to the
> mixer input.
>
> If it works with the high level input, then try the low level input
> again - the 1mW input removes the attenuator and adds the gain of the Q6
> stage.
>
> 73.
> Don W3FPR
>
> On 11/20/2015 11:22 AM, Dave Sergeant wrote:
> > My XV50, which worked fine for this summer's sporadic E season, has
> > suddenly gone faulty and has no output in either CW or SSB. The input
> > from the K2 is present, although of course 5mW is pretty hard to
> > measure accurately with my scope. There is also no signal at the input
> > of the power amplifier module, but if I connect my scope probe to C48,
> > at the output of the bandpass filter, and key the rig I have more or
> > less correct output and a good 50MHz sinewave on the scope - as soon
> > as I remove the probe the output disappears again. So the output
> > module is fine and the fault would seem to be related to the U6 buffer
> > or the bandpass filter. I am a bit mystified and need to sit down and
> > work out what is really happening.
> >
> >
>

http://davesergeant.com

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g3ymc

Re: XV50 no output

And it turned out to be the cable from the K2 to the transverter. The
pin of the BNC plug at the XV50 end had pushed back so not making.
Together with the BNC/phone adaptor at the K2 end which is not the best
arrangement. I obviously need to make up a couple of proper phono-BNC
cables.

I assume the BNC sockets on the XV50 are 50 ohm variants. I know the
pin diameters of 50 and 75 ohm are supposed to be compatible but maybe
that on the off the shelf BNC lead I used, presumably 75 ohm, has
thicker pins which caused the issue.

73 Dave G3YMC

On 21 Nov 2015 at 10:45, Dave Sergeant wrote:

> Thanks Don. Having looked at it again it does actually look as if the
> output from the K2 transverter socket is missing or very low. I got a
> bit confused about levels (as well as making typos) and I should most
> definitely be able to see the 1mW on my scope (632mV p-p). I did have to
> tighten up the locknuts on the phono sockets at the K2, maybe there is
> an open circuit or short circuit there as well. Will take the K2 apart
> again later and check, but the XV50 is probably OK.
>
> 73 Dave G3YMC
>
> On 20 Nov 2015 at 14:28, Don Wilhelm wrote:
>
> > Dave,
> >
> > Be cautious with conclusions when probing with a 'scope probe in the
> > 50 MHz section of the XV50. The probe can pick up RF and produce
> > false output indications. The fact that you can induce output by
> > probing C48 does normally indicate that U6 and U7 are capable of
> > producing a signal. Check the LO signal. If that is good, then the
> > problem may be in the 28 MHz bandpass or the mixer.
> >
> > I am puzzled by your reference to 5mW. The K2 with the K60XV has 1mW
> > output - was that a typo?
> >
> > If you want to probe the 28 MHz IF in the XV50, you can re-plug the
> > transverter for up to 5 watts input and you should be able to follow
> > the signal path through the 28 MHz bandpass filter - all the way to
> > the mixer input.
> >
> > If it works with the high level input, then try the low level input
> > again - the 1mW input removes the attenuator and adds the gain of the
> > Q6 stage.
> >
> > 73.
> > Don W3FPR
> >
> > On 11/20/2015 11:22 AM, Dave Sergeant wrote:
> > > My XV50, which worked fine for this summer's sporadic E season, has
> > > suddenly gone faulty and has no output in either CW or SSB. The
> > > input from the K2 is present, although of course 5mW is pretty hard
> > > to measure accurately with my scope. There is also no signal at the
> > > input of the power amplifier module, but if I connect my scope probe
> > > to C48, at the output of the bandpass filter, and key the rig I have
> > > more or less correct output and a good 50MHz sinewave on the scope -
> > > as soon as I remove the probe the output disappears again. So the
> > > output module is fine and the fault would seem to be related to the
> > > U6 buffer or the bandpass filter. I am a bit mystified and need to
> > > sit down and work out what is really happening.
> > >
> > >

Guy Olinger K2AV

Re: XV50 no output

Hi Dave, and to the masses of readers we can hear breathing in the
background...

I've surely done that myself, once with the equipment out and ready to ship
before logic gained the upper hand and I started checking cords and
connectors, finally detecting a male BNC on a cord with a retracted center
pin. Sound familiar? :>)

So many of us have had experiences like this. Cord goes bad and to start
off we spend time trying to figure what's the matter with the box, the K3,
the transverter, etc.

One local ham went nearly nuts thinking his box had been supplied with
non-standard type F female chassis connectors until a friend discovered
that the male F connector in question had not been threaded in the
manufacturing process ! That story was source of a lot of local ham laughs.

Carefully checking the cords and connectors *first* seems to be
counter-intuitive. While logic says that connectors and wire in the cords
take all the mechanical abuse, our gut lurch is elsewhere. Maybe it's
because making cords is such a royal pain in the *ss and our subconscious
is rebelling against making another jumper.

I share your pain. Maybe half the time I take advantage of experience and
go after the cords first off. My personal gut lurch is still, "What the
&&$#@$$ is wrong with the <insert box name> now !!!"

73, Guy K2AV

On Saturday, November 21, 2015, Dave Sergeant <[hidden email]> wrote:

> And it turned out to be the cable from the K2 to the transverter. The
> pin of the BNC plug at the XV50 end had pushed back so not making.
> Together with the BNC/phone adaptor at the K2 end which is not the best
> arrangement. I obviously need to make up a couple of proper phono-BNC
> cables.
>
> I assume the BNC sockets on the XV50 are 50 ohm variants. I know the
> pin diameters of 50 and 75 ohm are supposed to be compatible but maybe
> that on the off the shelf BNC lead I used, presumably 75 ohm, has
> thicker pins which caused the issue.
>
> 73 Dave G3YMC
>

David Olean

Re: XV50 no output

I think I win the prize for not checking the obvious. I turned on my
homebrew 160 meter 3-1000Z amp and saw only 400 watts instead of the normal
1300 watts out. I ended up taking the amp apart, and measuring all the RF
components. I tested the cables. I had the PI network coils out. I removed
the blocking caps. I ripped into the cathode input circuit...everything that
could possibly cause a problem. I found nothing that looked wrong or bad.
Then I discovered that my Bird 43 meter circuit was bad. It made for a good
laugh at my expense. I rationalized it all knowing that the amp had been
checked out really well.

Dave K1WHS
----- Original Message -----
From: "Guy Olinger K2AV" <[hidden email]>
To: "Dave Sergeant" <[hidden email]>
Cc: <[hidden email]>
Sent: Saturday, November 21, 2015 4:02 PM
Subject: Re: [Elecraft] XV50 no output

> Hi Dave, and to the masses of readers we can hear breathing in the
> background...
>
> I've surely done that myself, once with the equipment out and ready to
> ship
> before logic gained the upper hand and I started checking cords and
> connectors, finally detecting a male BNC on a cord with a retracted center
> pin. Sound familiar? :>)
>
> So many of us have had experiences like this. Cord goes bad and to start
> off we spend time trying to figure what's the matter with the box, the K3,
> the transverter, etc.
>
> One local ham went nearly nuts thinking his box had been supplied with
> non-standard type F female chassis connectors until a friend discovered
> that the male F connector in question had not been threaded in the
> manufacturing process ! That story was source of a lot of local ham
> laughs.
>
> Carefully checking the cords and connectors *first* seems to be
> counter-intuitive. While logic says that connectors and wire in the cords
> take all the mechanical abuse, our gut lurch is elsewhere. Maybe it's
> because making cords is such a royal pain in the *ss and our subconscious
> is rebelling against making another jumper.
>
> I share your pain. Maybe half the time I take advantage of experience and
> go after the cords first off. My personal gut lurch is still, "What the
> &&$#@$$ is wrong with the <insert box name> now !!!"
>
> 73, Guy K2AV
>
> On Saturday, November 21, 2015, Dave Sergeant <[hidden email]>
> wrote:
>
>> And it turned out to be the cable from the K2 to the transverter. The
>> pin of the BNC plug at the XV50 end had pushed back so not making.
>> Together with the BNC/phone adaptor at the K2 end which is not the best
>> arrangement. I obviously need to make up a couple of proper phono-BNC
>> cables.
>>
>> I assume the BNC sockets on the XV50 are 50 ohm variants. I know the
>> pin diameters of 50 and 75 ohm are supposed to be compatible but maybe
>> that on the off the shelf BNC lead I used, presumably 75 ohm, has
>> thicker pins which caused the issue.
>>
>> 73 Dave G3YMC
>>
> ______________________________________________________________
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>
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G3XVR

Re: XV50 no output

In reply to this post by Guy Olinger K2AV

I remember buying some cheap BNC patch leads at a rally which worked fine.
After a swap around my RX went deaf and I couldn't work out what was wrong.
After a lot of diagnosis I started to inject a large signal and worked all
the way back to the BNC antenna input socket, where I found that the cheap
leads were 75 Ohm video types with fat centre pins that had splayed out the
centre of the socket so that while they worked, there was no connection to
the centre pin of a thinner 50 Ohm plug. They went straight in the bin
after that.

Danny, G3XVR

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of Guy
Olinger K2AV
Sent: 21 November 2015 16:03
To: Dave Sergeant
Cc: [hidden email]
Subject: Re: [Elecraft] XV50 no output

Hi Dave, and to the masses of readers we can hear breathing in the
background...

I've surely done that myself, once with the equipment out and ready to ship
before logic gained the upper hand and I started checking cords and
connectors, finally detecting a male BNC on a cord with a retracted center
pin. Sound familiar? :>)

So many of us have had experiences like this. Cord goes bad and to start off
we spend time trying to figure what's the matter with the box, the K3, the
transverter, etc.

One local ham went nearly nuts thinking his box had been supplied with
non-standard type F female chassis connectors until a friend discovered that
the male F connector in question had not been threaded in the manufacturing
process ! That story was source of a lot of local ham laughs.

Carefully checking the cords and connectors *first* seems to be
counter-intuitive. While logic says that connectors and wire in the cords
take all the mechanical abuse, our gut lurch is elsewhere. Maybe it's
because making cords is such a royal pain in the *ss and our subconscious is
rebelling against making another jumper.

I share your pain. Maybe half the time I take advantage of experience and go
after the cords first off. My personal gut lurch is still, "What the &&$#@$$
is wrong with the <insert box name> now !!!"

73, Guy K2AV

On Saturday, November 21, 2015, Dave Sergeant <[hidden email]> wrote:

> And it turned out to be the cable from the K2 to the transverter. The
> pin of the BNC plug at the XV50 end had pushed back so not making.
> Together with the BNC/phone adaptor at the K2 end which is not the
> best arrangement. I obviously need to make up a couple of proper
> phono-BNC cables.
>
> I assume the BNC sockets on the XV50 are 50 ohm variants. I know the
> pin diameters of 50 and 75 ohm are supposed to be compatible but maybe
> that on the off the shelf BNC lead I used, presumably 75 ohm, has
> thicker pins which caused the issue.
>
> 73 Dave G3YMC
>

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Don Wilhelm-4

Re: XV50 no output

You must have had some older 75 ohm BNC connectors.
Those which comply with the 1978 standard IEC 169-8 will interchange
non-destructively - so says Wikipedia

73,
Don W3FPR

On 11/21/2015 2:44 PM, Danny Higgins wrote:

> I remember buying some cheap BNC patch leads at a rally which worked fine.
> After a swap around my RX went deaf and I couldn't work out what was wrong.
> After a lot of diagnosis I started to inject a large signal and worked all
> the way back to the BNC antenna input socket, where I found that the cheap
> leads were 75 Ohm video types with fat centre pins that had splayed out the
> centre of the socket so that while they worked, there was no connection to
> the centre pin of a thinner 50 Ohm plug. They went straight in the bin
> after that.
>
>

g3ymc

Re: XV50 no output

In reply to this post by G3XVR

Danny

Decent BNC connectors have identical pin diameters in both 75 and 50
ohms versions and are fully compatible (unlike N type which are
definitely incompatible). But obviously these cheaper ready made up
cables use cheap plugs so may well have fat pins.

As an interim measure I have taken a couple more of the cheap BNC/BNC
leads and chopped one of the plugs off and fitted a phono plug, which
at least gets round the problems of adaptors - still 75 ohms of course.
A quick search shows that all made up BNC-phono leads are 75 ohms so to
go to 50 ohm leads you really do need to make it up yourself - and I
don't seem to have any BNC plugs in the spares box at the moment.

This has got it up and running again, but I have revealed another issue
- the earthing of the phono sockets in the K60XV at the K2 end is not
ideal. Only the output phono has a grounding lug, the input phono
relies on earthing via the aluminium panel. Although there are crinkle
washers both sides of the socket the socket tends to wear loose every
time you put the plug in. The receive noise on the XV50 shows this, as
you wriggle the cable at that end the noise goes up and down. It really
needs a direct earth to the ground on the K60XV panel.

I guess now having got it going not much else will happen until the
sporadic E season starts next May...

73 Dave G3YMC

On 21 Nov 2015 at 19:44, Danny Higgins wrote:

> I remember buying some cheap BNC patch leads at a rally which worked
> fine. After a swap around my RX went deaf and I couldn't work out what
> was wrong. After a lot of diagnosis I started to inject a large signal
> and worked all the way back to the BNC antenna input socket, where I
> found that the cheap leads were 75 Ohm video types with fat centre pins
> that had splayed out the centre of the socket so that while they worked,
> there was no connection to the centre pin of a thinner 50 Ohm plug.
> They went straight in the bin after that.
>
> Danny, G3XVR
>

Don Wilhelm-4

Re: XV50 no output

Dave,
Properly tightened against the internal tooth lockwashers, those RCA
jacks should not loosen.
Unless someone used substitutes, they have a hex nut on each side of the
panel and an internal tooth lockwasher on each side of the panel too.
Use wrenches (spanners for you) or pliers and tighten them securely.
The internal tooth lockwashers need to 'bite' securely into the aluminum.

73,
Don W3FPR

On 11/21/2015 3:03 PM, Dave Sergeant wrote:

> This has got it up and running again, but I have revealed another issue
> - the earthing of the phono sockets in the K60XV at the K2 end is not
> ideal. Only the output phono has a grounding lug, the input phono
> relies on earthing via the aluminium panel. Although there are crinkle
> washers both sides of the socket the socket tends to wear loose every
> time you put the plug in. The receive noise on the XV50 shows this, as
> you wriggle the cable at that end the noise goes up and down. It really
> needs a direct earth to the ground on the K60XV panel.
>
>

Bob McGraw - K4TAX

Power meter inaccurate

In reply to this post by David Olean

You might be surprised at how many times I've assisted folks with low
transmitter power only to find their power meter was not accurate. It
happens to the best of us, regardless of how new or how expensive the
instrument might be.

A lesson I learned as a pilot and that is always have a "what if" in
your pocket. What if on landing approach I lower the landing gear and
one does not extend and lock? What if I pull back the throttles to
cruise setting after take-off and #2 quits. What if on a cold winter
day I take off, have the airplane off of the runway and look at the
panel only to discover the airspeed is zero! Well there's answers for
each of those, most of which I hope I never have to apply..........again!

73
Bob, K4TAX

On 11/21/2015 11:09 AM, Dave Olean wrote:
> Then I discovered that my Bird 43 meter circuit was bad. It made for a
> good laugh at my expense.

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