Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: zero-beating with separate xmitter/rcr  (Read 473 times)
WA8JNM
Member

Posts: 175




Ignore
« on: April 15, 2006, 02:18:39 PM »

A basic question...I have gotten back to playing with old novice, rock-bound transmitters and separate receivers.  What I can't remember is this: when I zero-beat my own signal by tuning my receiver until my own signal goes to "no tone", I assume i am listening exactly on my transmit freq., right? (Of course, I get no sidetone, which is itself a problem.) But, if I call CQ, where do I listen for a response?  Up just a bit, or down a bit, so the OM answering me has a CW tone? If he is answering me exactly on my freq., wouldn't he have "no" tone, just as mine has no tone?  And, if so, do I listen "up" a bit, or "down" a bit?  Or both, by tuning?  I know the answer is straight-forward, but I'm confused.  Thanks.

Dave
Logged
W5HTW
Member

Posts: 729


WWW

Ignore
« Reply #1 on: April 15, 2006, 05:14:12 PM »

You are correct.  When you tune your receiver to the "zero pitch" position, provided your receiver's BFO is off or accurately centered, you are "zero beat."  

Now, tune the receiver away from that zero beat frequency until you have a suitable tone from your own transmitter, perhaps 600-700 hertz. OR, if you have a tunable BFO, just rotate it for the desired pitch but now without touching the receiver's VFO.  

Someone calling you "dead on" your transmitter's frequency, will now be heard in your passband, at the same tone as your own transmitter sounded, or very close.  

However, if you happen to have tuned 1 KHZ low, and that person is calling 1 KZ above your transmitter frequency, you may not hear him.  Hence the practice of "tuning around" the frequency.

When answering another station the process is similar except you move the transmitter VFO instead of the receiver.  But for rockbound transmit, you are doing it correctly.  

With receivers that have an adjustable BFO, such as most of the Hammarlunds, Hallicrafters, and for example, the Collins 75S3B, if you do not have the BFO in its center of the passband, then you need to do that first.   With receivers such as the Drake R4B, which is what I use, there is no adjustable BFO.  Center the Passband control and tune to zero.  Then, tune slightly above and below the frequency after your CQ.

I also advise first listening with a wider passband or selectivity, such as 1.2 KHZ or even 2.1 KHZ, or whatever comes close in your receiver.  Then, when you have a station selected, simply sharpen the filter to suit you.

Ed
Logged
WA8JNM
Member

Posts: 175




Ignore
« Reply #2 on: April 16, 2006, 05:00:27 AM »

Ed,

Very helpful.  I had not thought of the BFO functionality in the zero-beat process. I usually use a Hammerlund HQ-180, so that is relevant to me. Your answer also solves the "sidetone" issue for me; if I am tuned correctly, I can monitor my own signal.  If My receiver is "dead-on" my freq., obviously there is no tone to monitor.  I also appreciate the thought of keeping the receive bandwidth broader until the QSO is established.

Surprising how a guy can forget this stuff in a mere 40 years.  (Or maybe I never knew it.  Smiley )

Thanks for the quick and clear advice.

Dave
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!