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XV432 Issues

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W3MW Don

XV432 Issues

I've just finished assembly of the XV432 kit, interfaced to a K3, and ran into two issues during alignment in Part VI, Filter Alignment.

First, during CW key-down, the voltage at TP5 peaks immediately, then slowly drops off until it is a volt or more lower than peak. Immediately re-keying gets a somewhat higher voltage than at un-key, but not at the peak. Letting it sit a minute or two, then re-keying, gets the original peak voltage back. Output power does the same fade.

Second, the 28 MHz filters don't seem to be aligning properly. I've set the cans at the set-points in the manual, but L15 and L16 seem to peak with the slugs out of the cans. L17 appears to peak ok, and the 432 filters both seem to peak fine. At the best point of alignment, I am getting less than 7 volts at TP5, vs, 10 required for full output. I've checked the K3 output, and the BNC cables, both are fine. The input section of the XV is easily able to overdrive the input to the 28 MHz filters, as evidenced by D10 and D11 lighting up at roughly half setting on the input attenuator. Max output from the PA is around 15 watts without lighting up D10 and D11. I've pulled and checked the five caps around the filters, all are within tolerance. Oscillator alignment was fine, 3v at TP1. I've tried re-aligning these three cans several times, including bottoming out the slugs and working back up, with no change.

I'm on the air with it at the moment, and it seems to be working other than the low power output.

Any thoughts?

Don W3MW

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Don Wilhelm-4

Re: XV432 Issues

Don,

The manual doesn't state that you must adjust for 10 volts at TP5.
Please read that section again.

It does say that you should not exceed 10 volts at TP5 during the
bandpass filter tuning.
If the output goes above 10 volts, use the input attenuator R22) to
bring the voltage down - perhaps in the vicinity of 5 volts, and then
continue to look for the peak tuning point for each inductor that is to
be adjusted.
Go back over the peaking procedure 3 or 4 times.

After you have peaked the bandpass filters, you will then adjust the
input attenuator to produce the correct output (use an external power
meter which is accurate at 432 MHz) while your selected maximum drive
level is applied from your transceiver.

After that (and while the transverter is producing 20 watts), you adjust
R10 (Power CAL) so the LEDs indicate 20 watts.

These 3 steps must be done in order - do not skip ahead or you will end
up with frustration. Also, do not drive the transverter for too long at
a time - particularly during the final power adjustments. Give enough
"break" time to let it cool between adjustment trials.

73,
Don W3FPR

On 8/6/2011 3:27 PM, W3MW Don wrote:

> I've just finished assembly of the XV432 kit, interfaced to a K3, and ran into two issues during alignment in Part VI, Filter Alignment.
>
> First, during CW key-down, the voltage at TP5 peaks immediately, then slowly drops off until it is a volt or more lower than peak. Immediately re-keying gets a somewhat higher voltage than at un-key, but not at the peak. Letting it sit a minute or two, then re-keying, gets the original peak voltage back. Output power does the same fade.
>
> Second, the 28 MHz filters don't seem to be aligning properly. I've set the cans at the set-points in the manual, but L15 and L16 seem to peak with the slugs out of the cans. L17 appears to peak ok, and the 432 filters both seem to peak fine. At the best point of alignment, I am getting less than 7 volts at TP5, vs, 10 required for full output. I've checked the K3 output, and the BNC cables, both are fine. The input section of the XV is easily able to overdrive the input to the 28 MHz filters, as evidenced by D10 and D11 lighting up at roughly half setting on the input attenuator. Max output from the PA is around 15 watts without lighting up D10 and D11. I've pulled and checked the five caps around the filters, all are within tolerance. Oscillator alignment was fine, 3v at TP1. I've tried re-aligning these three cans several times, including bottoming out the slugs and working back up, with no change.
>
> I'm on the air with it at the moment, and it seems to be working other than the low power output.
>
> Any thoughts?
>
> Don W3MW
>

W3MW Don

Re: XV432 Issues

Don,

Thanks for your reply. It's great to get feedback here so quickly,
especially as I managed to delay my question until a weekend.

I understand the section of the manual regarding 10 volts at TP5. What I
meant to indicate is that I cannot get anywhere near 9 or 10 volts at TP5
following the normal alignment procedure, regardless of whatever setting the
input attenuator is at. I've followed the procedure by the manual,
carefully, many times. Despite repeated passes through the peaking process
(many more than three or four, I'm afraid), I cannot get over 15 watts
output or over 7.5 volts at TP5 regardless of the input attenuator setting.
I've since checked the coils to be sure I have the correct ones in the
filter.

K3 is set up for 1.00 power out, as instructed.
The fact that the overload LEDs are lighting up at the high end setting of
the input attenuator leads me to believe that the IF in from the K3 is ok,
and that both pre-filter amplifier stages are working as intended.
Adjustments of FL1 and FL2 are smooth and have a clearly identifiable peak,
leading me to believe those are ok. I'm not seeing any voltage changes
elsewhere in the transmit chain, and the rest of the device voltages look
good.

I made several attempts at alignment since your email, with no more success
than earlier. As I am concerned that the PA module may be flaky, rather
than fry the thing by continuing to tune, it's going back to Elecraft on
Monday for them to have a look. I'll follow up here with the results.

Thanks again for your quick response.

73,

Don Appleby W3MW
[hidden email]

----- Original Message -----
From: "Don Wilhelm" <[hidden email]>
To: "W3MW Don" <[hidden email]>
Cc: <[hidden email]>
Sent: Saturday, August 06, 2011 5:15 PM
Subject: Re: [Elecraft] XV432 Issues

Don,

The manual doesn't state that you must adjust for 10 volts at TP5.
Please read that section again.

It does say that you should not exceed 10 volts at TP5 during the
bandpass filter tuning.
If the output goes above 10 volts, use the input attenuator R22) to
bring the voltage down - perhaps in the vicinity of 5 volts, and then
continue to look for the peak tuning point for each inductor that is to
be adjusted.
Go back over the peaking procedure 3 or 4 times.

After you have peaked the bandpass filters, you will then adjust the
input attenuator to produce the correct output (use an external power
meter which is accurate at 432 MHz) while your selected maximum drive
level is applied from your transceiver.

After that (and while the transverter is producing 20 watts), you adjust
R10 (Power CAL) so the LEDs indicate 20 watts.

These 3 steps must be done in order - do not skip ahead or you will end
up with frustration. Also, do not drive the transverter for too long at
a time - particularly during the final power adjustments. Give enough
"break" time to let it cool between adjustment trials.

73,
Don W3FPR

On 8/6/2011 3:27 PM, W3MW Don wrote:

> I've just finished assembly of the XV432 kit, interfaced to a K3, and ran
> into two issues during alignment in Part VI, Filter Alignment.
>
> First, during CW key-down, the voltage at TP5 peaks immediately, then
> slowly drops off until it is a volt or more lower than peak. Immediately
> re-keying gets a somewhat higher voltage than at un-key, but not at the
> peak. Letting it sit a minute or two, then re-keying, gets the original
> peak voltage back. Output power does the same fade.
>
> Second, the 28 MHz filters don't seem to be aligning properly. I've set
> the cans at the set-points in the manual, but L15 and L16 seem to peak
> with the slugs out of the cans. L17 appears to peak ok, and the 432
> filters both seem to peak fine. At the best point of alignment, I am
> getting less than 7 volts at TP5, vs, 10 required for full output. I've
> checked the K3 output, and the BNC cables, both are fine. The input
> section of the XV is easily able to overdrive the input to the 28 MHz
> filters, as evidenced by D10 and D11 lighting up at roughly half setting
> on the input attenuator. Max output from the PA is around 15 watts
> without lighting up D10 and D11. I've pulled and checked the five caps
> around the filters, all are within tolerance. Oscillator alignment was
> fine, 3v at TP1. I've tried re-aligning these three cans several times,
> including bottoming out the slugs and working back up, with no change.
>
> I'm on the air with it at the moment, and it seems to be working other
> than the low power output.
>
> Any thoughts?
>
> Don W3MW
>

Don Wilhelm-4

Re: XV432 Issues

Don,

OK, and please understand that you will not necessarily obtain 10 volts
at TP5. The voltage there is only relative, and is only used to
identify the peak - once the tuning peaks have been found, the voltage
there is no longer relevant. In other words, 10 volts at TP5 does not
indicate full output, you must use a wattmeter that is accurate at 432
MHz to determine the 20 watt level.

Can you measure the current that is being drawn while you attempt to get
20 watts output? If the current is excessive, there is a problem
between the PA module and the antenna.

Assuming that the efficiency is 50%, it will take about 3 to 3.5 Amperes
at 20 watts output. As I indicated, a higher current indicates that
there is a problem between the PA and the antenna output.
OTOH, if the current is lower, That indicates that the PA module is not
receiving adequate drive.
If that is the case, try increasing the bias slightly to see if that
gives any improvement.

My experience with the specifics of the XV432 is limited, so if the
problem is low drive to the PA module, it is best to email
[hidden email] - unfortunately, they take the weekend off for a
well deserved rest (we volunteers do not have that privilege).

73,
Don W3FPR

On 8/6/2011 10:49 PM, W3MW Don wrote:

> Don,
>
> Thanks for your reply. It's great to get feedback here so quickly,
> especially as I managed to delay my question until a weekend.
>
> I understand the section of the manual regarding 10 volts at TP5. What I
> meant to indicate is that I cannot get anywhere near 9 or 10 volts at TP5
> following the normal alignment procedure, regardless of whatever setting the
> input attenuator is at. I've followed the procedure by the manual,
> carefully, many times. Despite repeated passes through the peaking process
> (many more than three or four, I'm afraid), I cannot get over 15 watts
> output or over 7.5 volts at TP5 regardless of the input attenuator setting.
> I've since checked the coils to be sure I have the correct ones in the
> filter.
>
> K3 is set up for 1.00 power out, as instructed.
> The fact that the overload LEDs are lighting up at the high end setting of
> the input attenuator leads me to believe that the IF in from the K3 is ok,
> and that both pre-filter amplifier stages are working as intended.
> Adjustments of FL1 and FL2 are smooth and have a clearly identifiable peak,
> leading me to believe those are ok. I'm not seeing any voltage changes
> elsewhere in the transmit chain, and the rest of the device voltages look
> good.
>
> I made several attempts at alignment since your email, with no more success
> than earlier. As I am concerned that the PA module may be flaky, rather
> than fry the thing by continuing to tune, it's going back to Elecraft on
> Monday for them to have a look. I'll follow up here with the results.
>
> Thanks again for your quick response.
>
> 73,
>
> Don Appleby W3MW
> [hidden email]
>
> ----- Original Message -----
> From: "Don Wilhelm"<[hidden email]>
> To: "W3MW Don"<[hidden email]>
> Cc:<[hidden email]>
> Sent: Saturday, August 06, 2011 5:15 PM
> Subject: Re: [Elecraft] XV432 Issues
>
>
> Don,
>
> The manual doesn't state that you must adjust for 10 volts at TP5.
> Please read that section again.
>
> It does say that you should not exceed 10 volts at TP5 during the
> bandpass filter tuning.
> If the output goes above 10 volts, use the input attenuator R22) to
> bring the voltage down - perhaps in the vicinity of 5 volts, and then
> continue to look for the peak tuning point for each inductor that is to
> be adjusted.
> Go back over the peaking procedure 3 or 4 times.
>
> After you have peaked the bandpass filters, you will then adjust the
> input attenuator to produce the correct output (use an external power
> meter which is accurate at 432 MHz) while your selected maximum drive
> level is applied from your transceiver.
>
> After that (and while the transverter is producing 20 watts), you adjust
> R10 (Power CAL) so the LEDs indicate 20 watts.
>
> These 3 steps must be done in order - do not skip ahead or you will end
> up with frustration. Also, do not drive the transverter for too long at
> a time - particularly during the final power adjustments. Give enough
> "break" time to let it cool between adjustment trials.
>
> 73,
> Don W3FPR
>
>
> On 8/6/2011 3:27 PM, W3MW Don wrote:
>> I've just finished assembly of the XV432 kit, interfaced to a K3, and ran
>> into two issues during alignment in Part VI, Filter Alignment.
>>
>> First, during CW key-down, the voltage at TP5 peaks immediately, then
>> slowly drops off until it is a volt or more lower than peak. Immediately
>> re-keying gets a somewhat higher voltage than at un-key, but not at the
>> peak. Letting it sit a minute or two, then re-keying, gets the original
>> peak voltage back. Output power does the same fade.
>>
>> Second, the 28 MHz filters don't seem to be aligning properly. I've set
>> the cans at the set-points in the manual, but L15 and L16 seem to peak
>> with the slugs out of the cans. L17 appears to peak ok, and the 432
>> filters both seem to peak fine. At the best point of alignment, I am
>> getting less than 7 volts at TP5, vs, 10 required for full output. I've
>> checked the K3 output, and the BNC cables, both are fine. The input
>> section of the XV is easily able to overdrive the input to the 28 MHz
>> filters, as evidenced by D10 and D11 lighting up at roughly half setting
>> on the input attenuator. Max output from the PA is around 15 watts
>> without lighting up D10 and D11. I've pulled and checked the five caps
>> around the filters, all are within tolerance. Oscillator alignment was
>> fine, 3v at TP1. I've tried re-aligning these three cans several times,
>> including bottoming out the slugs and working back up, with no change.
>>
>> I'm on the air with it at the moment, and it seems to be working other
>> than the low power output.
>>
>> Any thoughts?
>>
>> Don W3MW
>>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

Don Wilhelm-4

Re: XV432 Issues

In reply to this post by W3MW Don

Don,

The overload LEDs are a different situation from your tuning/power out
situation.

Sometimes the overload LED indication is the result of noise getting
into the XVxxx firmware chip.
The cure for that noise is to connect a capacitor between the collector
and emitter (ground) or Q2 on the front panel board. Any value between
.001 and .01 uF should do nicely.

Of course, if you are driving the XV432 with a non-elecraft transceiver,
it could be that the overload condition is real - if the XV432 (or any
XV series transverter) detects RF before the Key-In signal is active, it
will cause the overload condition. I recall you are driving the XV432
from the K3, so I would attribute the LED flashing to a noise condition
on the overload signalling line, and the capacitor should calm it.

73,
Don W3FPR

On 8/6/2011 10:49 PM, W3MW Don wrote:

daleputnam

Re: XV432 Issues

In reply to this post by W3MW Don

L
Have a great day,
Dale - WC7S

-----Original Message-----
From: Don Wilhelm <[hidden email]>
Date: Sat, 6 Aug 2011 21:15:40
To: <[hidden email]>
Cc: <[hidden email]>
Subject: Re: [Elecraft] XV432 Issues

Don,

The manual doesn't state that you must adjust for 10 volts at TP5.
Please read that section again.

It does say that you should not exceed 10 volts at TP5 during the
bandpass filter tuning.
If the output goes above 10 volts, use the input attenuator R22) to
bring the voltage down - perhaps in the vicinity of 5 volts, and then
continue to look for the peak tuning point for each inductor that is to
be adjusted.
Go back over the peaking procedure 3 or 4 times.

After you have peaked the bandpass filters, you will then adjust the
input attenuator to produce the correct output (use an external power
meter which is accurate at 432 MHz) while your selected maximum drive
level is applied from your transceiver.

After that (and while the transverter is producing 20 watts), you adjust
R10 (Power CAL) so the LEDs indicate 20 watts.

These 3 steps must be done in order - do not skip ahead or you will end
up with frustration. Also, do not drive the transverter for too long at
a time - particularly during the final power adjustments. Give enough
"break" time to let it cool between adjustment trials.

73,
Don W3FPR

On 8/6/2011 3:27 PM, W3MW Don wrote:

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html