[Elecraft] K2 w/KSB CW reverse BFO

[Don Brown]

Hi

OK I will try to explain this. Your K2 will always transmit on the freque=
ncy indicated on the dial (notice the frequency shift on the dial if you =
turn on XIT when you transmit) When in receive the K2 MPU will offset the=
 VFO by the amount of your sidetone. That way if both operators are trans=
mitting on the same frequency and one has a sidetone of 600 Hz and the ot=
her has a side tone of 500 Hz then the operator with the 500 HZ tone will=
 hear the received CW signal as a 500 Hz tone while the operator with the=
 600 Hz sidetone will hear 600 Hz. Even though they are both transmitting=
 on the same frequency.

So if you are doing a performance test of your K2 then in CW mode listeni=
ng to your MPU clock at 4.000 MHz you should hear your sidetone frequency=
 in CW and CW rev and at each filter setting. The tone should not change =
frequency at all or very little.

When you select sideband things are different. If there is no audio input=
 from the mic then there will be no RF out on transmit. The receive and t=
ransmit frequency are the same. There is not an offset in the receiver. I=
f you were to apply a 600 Hz tone to the mic input then the K2 would tran=
smit a carrier offset +/-600 Hz depending on which sideband you selected.=
 The offset is determined by the frequency of the audio and the amplitude=
 of the RF carrier is determined by the amplitude of the audio.

Ok now with the theory behind us the reason you need to set the VFO to 40=
00.60 on LSB or 3999.40 on USB is to get the 600 Hz offset so you will he=
ar the tone. If you set the VFO to 4000.00 in USB or LSB then you are zer=
o beat and you will hear nothing. Making this test checks to make sure yo=
ur SSB filters are set up correctly. The test above checks out your CW fi=
lters. You should not try to adjust your filters with these tests. Use Sp=
ectrogram and a noise generator to set everything up then do the above te=
sts to make sure everything is right.

Don Brown
KD5NDB

----- Original Message -----
From: Wallace, Andy
Sent: Friday, November 01, 2002 8:08 AM
To: elecraft@mailman.qth.net
Subject: RE: [Elecraft] K2 w/KSB CW reverse BFO

> -----Original Message-----
> From: k6se@juno.com [mailto:k6se@juno.com]

> An unmodulated carrier on exactly 4000.000 kHz should be heard with a
> pitch of 600 Hz when your K2 is tuned to exactly 4000.000 kHz (not to
> 4000.600 or 3999.400).  If your K2's VFO readout is accurate, =20
> it should
> read "4.000.00" when that received signal's pitch is 600 Hz, no matter
> whether your receiver is on CW or CWR.

But what frequency does the K2 transmit on, when set that way?

I set my K1 frequency calibration on a separate receiver such that
the display reads the transmit frequency, so I know I am always in-band.

Whether the received freq is then off by the sidetone offset is not
as important to me. K1 is CW only so I don't have to worry about SSB
nets -- and even then, I cut my teeth on tube rigs that I had to readjust
every few minutes. It was just a part of ham radio and not a huge hassle.

-Andy
_______________________________________________
Elecraft mailing list: Elecraft@mailman.qth.net
You must be a list member to post to the list. =20
Postings must be plain text (no HTML or attachments). =20
See: http://mailman.qth.net/mailman/listinfo/elecraft
Elecraft Web Page: http://www.elecraft.com


--- StripMime Report -- processed MIME parts ---
multipart/alternative
  text/plain (text body -- kept)
  text/html
The reason this message is shown is because the post was in HTML
or had an attachment. Attachments are not allowed.
Please post in Plain-Text only.---