[Elecraft] [K3] IF output

[sr...@swbell.net]

I am trying to verify the output at the IF OUT jack on the back of
the K3. I have it connected to my K2 with the VFO set for 8215.00 and I see
or hear no signal at all. Shouldn't I see the output from the K3? Is the
signal that low that I won't even get a blip on the K2 receiver? Am I
missing something? I see no menu entry for enabling the IF output. HELP

Stan Rife
W5EWA

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[Alan Bloom]

You should hear whatever signals the K3 is tuned to. I'm assuming you
are connected to the IF OUT jack of the KXV3 or KXV3A.

If you haven't done the IF output mod:
http://www.elecraft.com/K3/mods/IF_Output_Buffer_Gain_Mod_Rev_A.pdf
then the signal level will be lower than at the K3 antenna connector.
But with the K3 preamp on, the difference is small. If you can clearly
hear something on the K3, then you should be able to hear it on the K2.

Alan N1AL

[Joe Planisky]

I don't think you'll hear much of anything on a K2 at 8.215 MHz.
That's well outside the 40m passband. The K2 does not have general
coverage RX.

73
--
Joe KB8AP

[Don Wilhelm]

Stan,

The K2 cannot receive that frequency - the dial may say so, but the
VFO/PLL has maxed out at about 7400 kHz (if you are tuning from 40
meters) and although the dial continues to increment, the actual
frequency will not go any higher. Even if it did, the bandpass filters
would probably attenuate the signal significantly. For the same reasons
I doubt that you can tune downward from 30 meters and get that low.
You will have to use a general coverage receiver.

73,
Don W3FPR

[sr...@swbell.net]

I thought about that and I guess that must be the case.

Stan Rife
W5EWA

73
--
Joe KB8AP

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01:35:00

[bo...@mchsi.com]

My K2 will tune to 8125 and I can hear the IF signal of the K3. It is weak, but audible. I have the IF mod installed in my K3

AJ9Q, Burl

----- Original Message -----
From: Don Wilhelm <w3...@embarqmail.com>
To: sr...@swbell.net
Cc: elec...@mailman.qth.net
Sent: Tue, 12 Jan 2010 16:06:55 -0600 (CST)
Subject: Re: [Elecraft] [K3] IF output

[Sverre Holm (LA3ZA)]

If you have an oscilloscope you can connect it and see the output. I have a
K3 which has the modified IF with higher output. I have a 5 MHz (-3 dB)
oscilloscope in my shack for monitoring. Even at 8.215 MHz it indicates up
to +/- 50 mV in the 40 m band (no ATT, no PRE). In other bands it is lower,
like about +/- 5mV (no ATT, no PRE) in the 80 m band. Due to the bandwidth
limitation of my oscilloscope, I guess these values should be doubled or so
to find the true values.

srife wrote:
>
> I am trying to verify the output at the IF OUT jack on the back of the
> K3.
>

-----
Sverre, LA3ZA

K2 #2198, K3 #3391
http://www.qslnet.de/member/la3za/K2/mod.html LA3ZA Unofficial Guide to K2
modifications
--
View this message in context: http://n2.nabble.com/IF-output-tp4294395p4294893.html
Sent from the [K3] mailing list archive at Nabble.com.

[sr...@swbell.net]

Don, can I use the SUB receiver in the K3 to do that? I have the KBPF3 in the sub receiver.

Stan Rife
W5EWA

Stan,

73,
Don W3FPR

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______________________________________________________________

[sr...@swbell.net]

I wonder if I could do the same with my HP 3403C True RMS meter?

Stan Rife
W5EWA

-----Original Message-----
From: elecraft...@mailman.qth.net
[mailto:elecraft...@mailman.qth.net] On Behalf Of Sverre Holm (LA3ZA)
Sent: Tuesday, January 12, 2010 4:18 PM
To: elec...@mailman.qth.net
Subject: Re: [Elecraft] [K3] IF output

-----
Sverre, LA3ZA

No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 9.0.725 / Virus Database: 270.14.136/2616 - Release Date: 01/12/10
01:35:00

______________________________________________________________

[Don Wilhelm]

Burl,

Some will do that, but most will not - it all depends on the exact value
of the capacitors in the VFO Range Select circuit - a few pF one way or
another makes a big difference. BTW, that is what setting the L30
adjustment to get the voltage at the left end of R30 is all about.

Yes, the weak reception is likely due to the bandpass filters.

73,
Don W3FPR

bo...@mchsi.com wrote:
> My K2 will tune to 8125 and I can hear the IF signal of the K3. It is weak, but audible. I have the IF mod installed in my K3
>
> AJ9Q, Burl
>
>

[Don Wilhelm]

Stan,

I should think you can - although you will have to be careful to listen
to the correct audio channel - it would be wierd to hear the real K3
received signal in one ear and the sub receiving the IF output signal in
the other.

73,
Don W3FPR

sr...@swbell.net wrote:
> Don, can I use the SUB receiver in the K3 to do that? I have the KBPF3 in the sub receiver.
>
>
> Stan Rife
> W5EWA
>
>

[sr...@swbell.net]

I was expecting to hear a carrier, but after I thought about it that
can't be the case.

With the IF connected to the Subreceiver I can tune around either
side of 8215 and hear QSO's. I have to have the Preamp on by I can hear
them. Would that be considered adequate? I have done the IF mod and used a
15K resistor in place of the original. I actually had a 10K & a 15K and Gary
Surrency said either one of them would work. So error on the side of caution
I used the 15K.

Stan Rife
W5EWA

-----Original Message-----
From: Don Wilhelm [mailto:w3...@embarqmail.com]
Sent: Tuesday, January 12, 2010 4:27 PM
To: sr...@swbell.net
Cc: elec...@mailman.qth.net

Subject: Re: [Elecraft] [K3] IF output

Stan,

I should think you can - although you will have to be careful to listen
to the correct audio channel - it would be wierd to hear the real K3
received signal in one ear and the sub receiving the IF output signal in
the other.

73,
Don W3FPR

sr...@swbell.net wrote:
> Don, can I use the SUB receiver in the K3 to do that? I have the KBPF3 in
the sub receiver.
>
>
> Stan Rife
> W5EWA
>
>

No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 9.0.725 / Virus Database: 270.14.136/2616 - Release Date: 01/12/10
01:35:00

______________________________________________________________

[Andrew Faber]

You can also try borrowing an Icom Pro series (or presumably their larger
radios as well), and hook the if out to the antenna input on the Pro, which
will then act as a bandscope for the K3 when tuned to 8215 kHz.. I do this
at P49Y (an idea from W0YK) and it works very well.
73, andy, ae6y

----- Original Message -----
From: "Alan Bloom" <al...@elecraft.com>
To: <sr...@swbell.net>
Cc: <elec...@mailman.qth.net>
Sent: Tuesday, January 12, 2010 1:55 PM
Subject: Re: [Elecraft] [K3] IF output

[sr...@swbell.net]

It's working. I tuned around and got some really loud signals even
without the preamp on. So I can move forward now trying to get the LP-Pan
working.

Thanks everyone,

Stan Rife
W5EWA

[Brett Howard]

Ok so I decided to do the IF mod as the P3 will be ordered when it comes
out and I'd like the increased sensitivity. I'm copying elecraft and K3
support cause I wanted to ask a simple question (as well as share the
results). First my question, I didn't have any 13K ohm resistors in
0805 size. So I put an 0603 resistor on the same pads. Will this be
ample or should I replace it with an 0805 for power rating reasons?

I made measurements before and after the modification and collected
results which I figured I'd share.

Signal Generator was a Rhode and Schwartz (sp?) model number unknown.
This signal generator was uncalibrated. However the spectrum analyzer I
was using was a very recently calibrated N9020A which our cal report
gave a clean bill of health and an absolute accuracy of 0.009dBm at
-50dBm. Agilent didn't specify the accuracy at -70 but it was getting
tighter as the amplitude went lower. I did not engage the preamp in the
analyzer.

I was making my measurements at -70dBm as its a "common ham amplitude".
I injected the signal at 7.040Mhz (cause I use that w/ my XG2 a lot) @
-70dBm. This input was verified on the spectrum analyzer at the end of
my cable to calibrate cable losses out of the system. I then measured
the output at the IF OUT port at 8.215Mhz.

Before
PreAmp off: -88.2dBm
PreAmp on: -77.0dBm

After
PreAmp off: -77.9dBm
PreAmp on: -66.9dBm

Looks like there is a tad bit of loss with the PA off (7.9dB) but then
again there is 3.1dB of gain with the PA on... Hopefully this jives
with intended results. If not hopefully its a useful data point.

Respectfully

~Brett (KC7OTG)

[Alan Bloom]

Brett,

Those numbers are similar to what I measured on my K3. It varies by
band, but before modification I was getting in the neighborhood of -6 dB
with preamp on and -17 dB with preamp off. After modification I
measured +4.5 dB with preamp on and -6.5 dB with preamp off (at 10 MHz).

A 0603 resistor should be fine. It's not dissipating significant power.

Alan N1AL