Looking for a KXPD1

[Jeff Davis-27]

Greetings all. I plan to order a KXPD1 paddle for a KX1 but thought I
would send a note here first to see if anyone has one for sale.
Contact me off the list (callsign at arrl.net) if you do.

Thanks es 73,

Jeff, KE9V
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[Ron Hahn (EI2JP)]

Colleagues,

I've just finished the receiver section of my K2 and have run into some
issues with alignment and test (part 2)..

First, the data:

4M Osc Test : 12,099.21 (set against frequency counter)

Ref Hi : 12,099
Ref Lo : 12,087
Range  : 12kHz

VCO Test : 8,913.08

VCO voltage readings within range on all bands

BFO Hi : 4917.62 >= 4916.3
BFO Lo : 4913.59 <= 4912.7 !!!
Range  : 4.03    >= 3.6kHz

All BFO components checked and confirmed to be correct..
BFO coil checked for shorts against resistor retainer..

Now, the problems...

1.  The BFO Lo is out of range;  This appears to have a knock on effect
with the filter cal.  I've checked all the component values and also
rechecked the 4MHz osc calibration, and can't get the BFO within range.
What could possibly be wrong? Built-in frequency counter seems to be
accurate when measuring an external reference.

2.  There is a constant broad-band S5 signal on the S-meter, and this can
be confirmed by plugging in the headphones.  ALC works normally. Injecting
a signal into the aerial input is masked by the internal signal (wherever
its coming from).  Changing filter settings has some impact on the signal
strength. This says to me that something is oscillating that shouldn't
be??

Thanks for your help,

Ron
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[Don Wilhelm-3]

Ron,

Yes, your BFO is out of range.  It may be that your BFO crystals are a
bit higher than they should be.  You could ask Elecraft for a
replacement or you can pad your crystals down a bit with capacitors.

There are two ways to pad the BFO - the first is to add capacitors in
parallel with C173 and C174 - try adding 47 pf to C174 and 120 pf to
C173 (other value combinations are possible, but try to keep the ratio
of the two values in the 1:2.6 range).

The second way to pad the frequency down is to add a small value
capacitor from the junction of the crystals and C174 to ground.  Do not
exceed 20 pf if you use this method.

The broadband signal may just be the effect of the BFO being off
frequency.  Wait until the BFO is correct before making any further
judgments.

73,
Don W3FPR

Ron Hahn wrote:
> Colleagues,
>
> I've just finished the receiver section of my K2 and have run into some
> issues with alignment and test (part 2)..
>

>
> BFO Hi : 4917.62 >= 4916.3
> BFO Lo : 4913.59 <= 4912.7 !!!
> Range  : 4.03    >= 3.6kHz
>
> All BFO components checked and confirmed to be correct..
> BFO coil checked for shorts against resistor retainer..
>
> Now, the problems...
>
> 1.  The BFO Lo is out of range;  This appears to have a knock on effect
> with the filter cal.  I've checked all the component values and also
> rechecked the 4MHz osc calibration, and can't get the BFO within range.
> What could possibly be wrong? Built-in frequency counter seems to be
> accurate when measuring an external reference.
>
> 2.  There is a constant broad-band S5 signal on the S-meter, and this
> can be confirmed by plugging in the headphones.  ALC works normally.
> Injecting a signal into the aerial input is masked by the internal
> signal (wherever its coming from).  Changing filter settings has some
> impact on the signal strength. This says to me that something is
> oscillating that shouldn't be??
>

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[Ron Hahn (EI2JP)]

On Tue, 27 Mar 2007, Don Wilhelm wrote:

> Ron,
>
> Yes, your BFO is out of range.  It may be that your BFO crystals are a bit
> higher than they should be.  You could ask Elecraft for a replacement or you
> can pad your crystals down a bit with capacitors.
>
Don,

I think I'll ask for replacement bfo crystals.

While waiting for them is it advisable to start on the transmitter or put
this kit aside until I have the receiver up and running properly?

> There are two ways to pad the BFO - the first is to add capacitors in
> parallel with C173 and C174 - try adding 47 pf to C174 and 120 pf to C173
> (other value combinations are possible, but try to keep the ratio of the two
> values in the 1:2.6 range).
>
Might try this in the short term if I have any in my junk box.

Thanks for the help,

Ron EI2JP

> The second way to pad the frequency down is to add a small value capacitor
> from the junction of the crystals and C174 to ground.  Do not exceed 20 pf if
> you use this method.
>
> The broadband signal may just be the effect of the BFO being off frequency.
> Wait until the BFO is correct before making any further judgments.
>
> 73,
> Don W3FPR
>

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[David Fleming-4]

Hi Ron.

I had the exact same problem. My numbers were very close to yours.
Rather than replacing the crystals, I added a 10pf capacitor from the
junction of the crystals and C174 to ground. That brought BFO Lo down
to where it needed to be. Sure beats waiting on new crystals, and
there's still no guarantee that new crystals will fix the problem. You
will need to get BFO Lo down in order to properly perform CAL FIL.


Ron Hahn wrote:

> BFO Hi : 4917.62 >= 4916.3
> BFO Lo : 4913.59 <= 4912.7 !!!
> Range  : 4.03    >= 3.6kHz

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[Leigh L. Klotz Jr WA5ZNU]

On Gary's advice, I used 2.7pF.  The capacitor can affect stability so
be sure to use a temperature stable one such as NP0 type.
73,
Leigh/WA5ZNU
On Tue, 27 Mar 2007 8:06 am, David Fleming wrote:

> Hi Ron.
>
> I had the exact same problem. My numbers were very close to yours.
> Rather than replacing the crystals, I added a 10pf capacitor from the
> junction of the crystals and C174 to ground. That brought BFO Lo down
> to where it needed to be. Sure beats waiting on new crystals, and
> there's still no guarantee that new crystals will fix the problem. You
> will need to get BFO Lo down in order to properly perform CAL FIL.
>
>
> Ron Hahn wrote:
>
>>  BFO Hi : 4917.62 >= 4916.3
>>  BFO Lo : 4913.59 <= 4912.7 !!!
>>  Range  : 4.03    >= 3.6kHz
>
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[RBrigham1]

Ron and Don,
I experienced the same issue this weekend but the problem was not as bad. My BFO Lo was 4912.83 with a range of about 4.5MHz. One of the solutions mentioned in the Troubleshooting paragraph was to check the 41uH BFO inductor, and if necessary, add a turn or two. I had noticed that one of the two leads had popped out of its adhesive where it exited the toroid so I speculated that it had come unwound by one turn.  I added one turn to the inductor and now my BFO Lo is right at 4912.71. Unless more knowledgable folks say otherwise, I'm leaving it there.  
73
Rob
KC6ROC K2#5924

David Fleming <[hidden email]> wrote:

>Hi Ron.
>
>I had the exact same problem. My numbers were very close to yours.
>Rather than replacing the crystals, I added a 10pf capacitor from the
>junction of the crystals and C174 to ground. That brought BFO Lo down
>to where it needed to be. Sure beats waiting on new crystals, and
>there's still no guarantee that new crystals will fix the problem. You
>will need to get BFO Lo down in order to properly perform CAL FIL.
>
>
>Ron Hahn wrote:
>
>> BFO Hi : 4917.62 >= 4916.3
>> BFO Lo : 4913.59 <= 4912.7 !!!
>> Range  : 4.03    >= 3.6kHz
>
>_______________________________________________
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>Post to: [hidden email]
>You must be a subscriber to post to the list.
>Subscriber Info (Addr. Change, sub, unsub etc.):
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>
>Help: http://mailman.qth.net/subscribers.htm
>Elecraft web page: http://www.elecraft.com
>

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