[K3] Loss of Gain below 550Hz filter width - firmware problem?

[M0XDF]

You may remember I have a problem with my K3 whereby dropping the  
filter width below 550Hz means I loose almost all AF gain.

I have just had a little time to look into it.
I was running the latest Beta software (1.96) which I see is now  
production.
I've now loaded the latest production code, but the problem is still  
there.

On a whim, I loaded 1.58 which I had hanging around from previous  
tests and everything works just great - right the way down to 50Hz  
filter width.

I then tried standard production f/w v 1.96 again and the problem was  
gone, but that was before it had loaded the DSP code (I didn't realise  
it hadn't competed the load) and once the DSP loaded, the problem is  
back.
I then tried v1.88 and the problem is still there.
I worked backwards through versions I have (I may not have them all)  
until I got to version 1.66 which still had the problem, but 1.58 does  
not. So this looks like a problem with DSP1 code from somewhere after  
v1.48 of DSP onwards.
I have now restored to the latest version.
I noticed the gain on the 1.58 code is considerably higher than on the  
latest code anyway.
The IIr trick doesn't make a difference to this.

I understand other people don't have this problem, so what is it that  
makes my K3 unique?

I have the following filters:
slot 1 - empty awaiting KFL3B-FM; FL1 BW = 0, FL1 FRQ = 0, FL1 GN = 0,  
FL1 ON = NO
slot 2: KFL3A-6K;     FL2 BW = 6.00, FL2 FRQ = 0, FL2 GN = 4db, FL2 ON  
= YES
slot 3 - KFL3A-2.8K; FL3 BW = 2.80, FL3 FRQ = 0, FL3 GN = 4db, FL3 ON  
= YES
slot 4 - KFL3A-1.8K; FL4 BW = 1.80, FL4 FRQ = 0, FL4 GN = 4db, FL4 ON  
= YES
slot 5 - KFL3A-400;  FL5 BW = 0.40, FL5 FRQ = 0, FL5 GN = 4db, FL5 ON  
= YES

With the following options:
KAT3, KPA3, KBPF3, KXV3, KTCx03-01

No mods yet.

You'll note this problem occurs below 550Hz, but that I have the 400Hz  
filter installed and it does switch filters at the correct point.

So suggestions anyone?
73 de M0XDF, K3 #174
--
Ok, so what's the speed of Dark?

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[Vic K2VCO]

David Ferrington, M0XDF wrote:
> You may remember I have a problem with my K3 whereby dropping the filter
> width below 550Hz means I loose almost all AF gain.
> So suggestions anyone?


Does turning off RX EQ help?
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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[M0XDF]

both Rx & Tx EQ have been left flat - but if you mean taping the AFX  
key, it makes no difference.

Just to be sure, there isn't another config option or switch I've  
missed, is there?
--
If all is not lost, where is it?

On 4 Jun 2008, at 01:23, Vic K2VCO wrote:

> David Ferrington, M0XDF wrote:
>> You may remember I have a problem with my K3 whereby dropping the  
>> filter width below 550Hz means I loose almost all AF gain.
>> So suggestions anyone?
>
>
> Does turning off RX EQ help?
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[M0XDF]

Looks like this was something I caused many months ago and the data  
table appears to have been wrong (I'm waiting for Lyle to confirm to  
me that’s the right description of the cause).

I removed all the current firmware from the K3 Firmware folder and  
forced the Utility to get it all from the server and then forced it to  
load everything, including the data table. That has fixed it :-)

Once again, Elecraft shows its quality in its responses to its  
customers - even if we do cause them problems now and then :-)
73 de M0XDF, K3 #174
--
We can't solve problems by using the same kind of thinking we used  
when we
created them. -Albert Einstein, physicist, Nobel laureate (1879-1955)

On 4 Jun 2008, at 02:23, Lyle Johnson wrote:

> Hello David!
>
>> I don't have a 500Hz filter and I did say it worked at a very early  
>> version of f/w. And yes I'm loading all the files.
>> I'll try disabling various filters tomorrow.
>
> Yes, I just now am getting caught up on the email thread.
>
> Since the roofing filter is not being switched between 500 Hz and  
> 550 Hz, it is not likely the problem.
>
> At 500 Hz, however, a different IF filter scheme occurs in the DSP.  
> Please reload the DSP data table, using the latest from the server.  
> If you are computer savvy and know where the current DTBL file is  
> located n your computer, please delete it first, so we can be sure  
> the correct DTBL file is safely loaded into your K3.  The DTBL  
> changed with release 1.49 of the DSP which is approximately the  
> version of DSP code you started having trouble with (1.48).
>
> If this doesn't correct the problem, you may need to perform an  
> EEINIT.  Wayne may have some suggestions before you do that, however.
>
> 73,
>
> Lyle KK7P

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