Re: For what is a crystal spotter used?


wb6ogd
 

Hey guys,
I joined you group just to educate myself on another rig that's out there.
So, I don't really have a dog in this show but...

It seems to me that you could just make a simple mod to the Jumper, why do you need a whole
new gadget.
You just need to power the oscillator and cut power(or drive) to the final like all old novice type
transmitters did it.

If you take the crystal out of the FET Jumper oscillator and put it in an external bipoler oscillator,
are you sure its even going to be on the same frequency?  Ok, with a regen receiver a few KHz
isn't really going to matter.  Can't you just put a mark on the Rx dial where your crystal frequencies
are?  Even if its off a little, when you call CQ (the only practical way to get a contact I would think),
with the regen selectivity, you are going to hear them over the large passband, no?

As another little kit project, ok, I can see that it will be fun and a little educational, but...
Back to my hole,
73,
Gary
WB6OGD

On 1/7/2021 6:32 PM, griffithsesq.robert via groups.io wrote:
Thanks Jim. After reviewing the schematic diagram of your Crystal Spotter, I was trying to figure out how/where it was connected to the Bayou Jumper. A Bayou “Blue Tooth” connection. Neat! 73. Griff NE3I

Robert Alan Griffiths
On Jan 7, 2021, at 3:51 PM, Jim, N5IB <n5ib@juno.com> wrote:

A crystal spotter is just a simple oscillator which will emit a very low level signal when a crystal is attached. It's used to locate the crystal's operating frequency in a receiver, when the receiver is not slaved to the same oscillator as its companion transmitter.

It's very useful with the Bayou Jumper, which has a wide pass band regenerative receiver, completely independent of the transmitter. If you're calling CQ with a Bayou Jumper you need to know where on the receiver dial to look for replies, since most operators using modern VFO controlled transceivers will zero beat your signal. It also helps to find out if there is other activity on your crystal frequency so you won't QRM them.

The spotter does not have to be connected to the receiver, just placed nearby. Enough signal leaks out to be easily heard.

BTW - whenever you are the "other op" trying to call and work a Bayou Jumper, remember that poor fellow has a regen. It's wide as a barn door, very sensitive, but he has to manually throw a switch and then perhaps tweak the tuning a bit to get back to where he was. His or her tuning may be as much as a couple kHz or more from a dead-on zero beat. So the typical "drop your call once" won't cut it.
Sending "callsign callsign de mycall mycall AR" is makes it much easier for that poor schmuck :^))
Back in the "spy days" the home station would call the outstation for several minutes to allow time for the hard pressed agent to get everything tweaked up.

second BTW - because of all this, a Jumper-to-Jumper QSO is a real challenge and an accomplishment to be savored.

Jim, N5IB
007
Bayou Jumper almost WAS.... -AK







Join main@4SQRP.groups.io to automatically receive all group messages.