K2 Low transverter drive level

[Barry Horning]

I have the K60XV installed on my K2/100 driving my 144MHz transverter. When
testing I was able to get the full range of output up to the 1.2mW level,
however as soon as the KAT100 is linked in the output power is limited to
0.2mW regardless of the setting of the power output. This sounds like the
ATU is loading the transverter output but the manual errata notes with the
kit (Rev A-4) only recognise a similar problem with the KAT2. Is there a
similar problem with the KAT100? This happens even when operating the
transverter drive into a 50 ohm load without the transverter.

To summarise: Without KAT100 9 pin connector connected full range
transverter Tx drive output; with the ATU linked in the maximum transverter
drive is 0.2mW. I cannot find anything on this list to help, is there
somebody out there with a suggestion please?

73

Barry GM4TOE




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[Don Wilhelm-4]

Barry,

A similar problem occurs with the KAT2 because the driver for VRFDET in
the KAT2 is not a tri-state device.  The KAT100 uses a tri-state driver
and should not cause the problem you state if it is working correctly.

It is possible that the U6 in the KAT100 is not operating correctly, but
before replacing it, check a few related items:

First measure the voltage on U6 pin 8 while transmitting to one of the
Transverter bands with the K60XV low power output active - the voltage
should remain at zero (this enable signal comes from the KAT100 firmware
chip and is not an indicator that U6 is faulty, but may indicate a bad
output from U1).

If the U6 pin 8 check shows no problem, then disconnect only pin 7 from
the K2 to KAT100 cable and see if the K60XV low level output is normal -
if it is, there is something wrong with the VRFDET path inside the
KAT100.  Check soldering at C38, C30, C56, R9 and U6 pin 6 to be certain
there are no solder splashes and a minimum amount of solder was used.  
If all that checks out, replace U6.

73,
Don W3FPR

Barry Horning wrote:

> I have the K60XV installed on my K2/100 driving my 144MHz transverter. When
> testing I was able to get the full range of output up to the 1.2mW level,
> however as soon as the KAT100 is linked in the output power is limited to
> 0.2mW regardless of the setting of the power output. This sounds like the
> ATU is loading the transverter output but the manual errata notes with the
> kit (Rev A-4) only recognise a similar problem with the KAT2. Is there a
> similar problem with the KAT100? This happens even when operating the
> transverter drive into a 50 ohm load without the transverter.
>
> To summarise: Without KAT100 9 pin connector connected full range
> transverter Tx drive output; with the ATU linked in the maximum transverter
> drive is 0.2mW. I cannot find anything on this list to help, is there
> somebody out there with a suggestion please?
>
>  

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[Barry Horning]

I have tried the tests suggested by Don and all appears to be OK. Just in
case I was deluding myself I then conducted the following tests which may
give a pointer to a possible firmware glitch. Everything is absolutely
reproduceable and I can live with the oddities to get the transverters
working:
Set-up is K2/100, KAT100, K60XV and ssb, noise blanker and 160m modules
installed. Powermeter on ATU output and dummy load on transverter drive
output from K60XV.
1) Test frequency 28.3MHz High Power via ATU - TUNE gives 20w output and
tunes ATU before switching back to Receive - in other words perfectly normal
2) DISPLAY + TUNE gives adjustable output to 100w as per specification
3) Switch to transverter band, power control set for 1.2mW output (LP)
pressing TUNE gives a maximum of 0.21mW not adjustable. Normal microphone
input does give full 1.2mW on Tx.
4) Press DISPLAY + TUNE and I can vary the power out from 0 to 1.2mW
5) BUT and this is the nub of the problem I think: Checking MENU ATU shows
that the ATU has reset itself to 1.0-1 NOT Auto.
6) Now TUNE alone on transverter band (without pressing DISPLAY as well)
allows power out to vary over full range 0 to 1.2mW
7) Resetting the ATU to Auto reverts to the situation in step 3 above.
8) Disconnecting the ATU when pressing TUNE on transverter band it is
possible to vary the power out as expected 0 to 1.2mW.

Having said this I now know how to drive my transverters by setting the ATU
off when setting-up. Incidentally my 2m transverter has a 470 ohm pot as the
input power control and the K2 does not like this and turns the power back
anyway, the 70cm transverter has a 3dB 50 ohm pad at the input and the K2
will drive this to the full 1.2mW.

May I say that I am highly impressed with the support (especially the speed
of reaction from Don) offered from this email list, it cannot be bettered.

73

Barry GM4TOE



-----Original Message-----
From: Don Wilhelm [mailto:[hidden email]]
Sent: 11 September 2007 14:25
To: Barry Horning
Cc: [hidden email]
Subject: Re: [Elecraft] K2 Low transverter drive level

Barry,

A similar problem occurs with the KAT2 because the driver for VRFDET in
the KAT2 is not a tri-state device.  The KAT100 uses a tri-state driver
and should not cause the problem you state if it is working correctly.

It is possible that the U6 in the KAT100 is not operating correctly, but
before replacing it, check a few related items:

First measure the voltage on U6 pin 8 while transmitting to one of the
Transverter bands with the K60XV low power output active - the voltage
should remain at zero (this enable signal comes from the KAT100 firmware
chip and is not an indicator that U6 is faulty, but may indicate a bad
output from U1).

If the U6 pin 8 check shows no problem, then disconnect only pin 7 from
the K2 to KAT100 cable and see if the K60XV low level output is normal -
if it is, there is something wrong with the VRFDET path inside the
KAT100.  Check soldering at C38, C30, C56, R9 and U6 pin 6 to be certain
there are no solder splashes and a minimum amount of solder was used.  
If all that checks out, replace U6.

73,
Don W3FPR

Barry Horning wrote:
> I have the K60XV installed on my K2/100 driving my 144MHz transverter.
When

> testing I was able to get the full range of output up to the 1.2mW level,
> however as soon as the KAT100 is linked in the output power is limited to
> 0.2mW regardless of the setting of the power output. This sounds like the
> ATU is loading the transverter output but the manual errata notes with the
> kit (Rev A-4) only recognise a similar problem with the KAT2. Is there a
> similar problem with the KAT100? This happens even when operating the
> transverter drive into a 50 ohm load without the transverter.
>
> To summarise: Without KAT100 9 pin connector connected full range
> transverter Tx drive output; with the ATU linked in the maximum

transverter
> drive is 0.2mW. I cannot find anything on this list to help, is there
> somebody out there with a suggestion please?
>
>  


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