Receiver Alignment Hookup

[2FB327]

After reading the repair manual and the owners manual for my signal generator, I need some help. As stated above in the Cobra repair manual, my questions are:
1. Where do you hook up the VTVM? Is there a way to do this with a DVM?
2. If someone could explain how you do it, it would be so helpful.
Thanks

 

[GnG8d]

At the AF output. Your DVM should accomplish the same thing, but may load the AF down.

BTW, I've read and tried using a scope to separate the signal from the noise and prefer that method.

 

[sonoma]

a dvm does not work. you need a meter with a needle on it to peak with. you hook it to the speaker section .

 

[Tallman]

The Oscilloscope works well for this too.

 

[2FB327]

Thanks your the man, could you recommend something that's available, and your saying it plugs in the external speaker jack.

 

[GnG8d]

a dvm does not work. you need a meter with a needle on it to peak with. you hook it to the speaker section .

You're exactly right, I keep an analog meter here for peaking (or dipping) circuits, but I tend to grab a scope probe for that stuff.

 

[2FB327]

You're exactly right, I keep an analog meter here for peaking (or dipping) circuits, but I tend to grab a scope probe for that stuff.

Would you be so kind as to explain how you use the scope to accomplish this.

 

[Radio Tech]

As others said a scope or VTVM for this operation.
If you do not have either you can run down to your local RS or walmart or Lowes and pick up a cheap analog meter. 10 to 15 bucks. Then google RF-probe and build you one.
Now some will tell you a DVM will work but the responce is a bit slow and cause you to over shoot you measurment.

 

[GnG8d]

Now some will tell you a DVM will work but the responce is a bit slow and cause you to over shoot you measurment.

Unless you are a very, very patient person.

 

[Radio Tech]

Unless you are a very, very patient person.

Most are not lol

The RF-probe incase some need

Heathkit Model 309-C RF Probe -- Schematic diagram
http://www.nostalgickitscentral.com/...chema_309c.pdf

Heathkit Model 309-C RF Probe -- Assembly Instructions
http://tubularelectronics.com/Heath_...RF%20probe.pdf

Here is the Heathkit V-7a VTVM brochure / write-up.
http://www.w6ze.org/Heathkit/Heathkit_019_V7a.pdf

DIY BUILD your own RF Probe !!

RF Probe from a Sharpie by KC0WOX
http://golddredgervideo.com/kc0wox/rfprobe.htm

Classic RF Probe by N5ESE
http://n5ese.com/rfprobe1.htm

Ballpoint RF Probe by N5ESE
http://www.n5ese.com/rfprobe2.htm

How KI6DS Built the N5ESE RF Probe - NorCal QRP Club
http://www.norcalqrp.org/KI6DSrfprobe.htm

Diode Selection for RF Probes - Clifton Labs
http://www.cliftonlaboratories.com/d..._rf_probes.htm

Hendricks Kits - RF Probe
http://www.qrpkits.com/rfprobe.html

 

[GnG8d]

He won't need an RF probe for AF, but those are some cool DIY links if an RF probe is needed

 

[2FB327]

Radio Tech, I have seen the probes, are you saying that you hook the rf probe to the scope and then probe the radio?
If so at the speaker jack?
I probably have the things to build a probe, or go to the store and get an analog meter, but I'm more interested in how to hook up the scope to do it.

 

[GnG8d]

I didn't realize you had a scope, just plug your probe in and clip it to a speaker wire. Watch the signal as you peak the circuit.

 

[Radio Tech]

Oh, so you have a scope. Some folks would probe the speaker output. Connect you SG to the ant in and set the output to a minimum level. Adjust your scope so you have a few division displayed. The problem here is signal to noise. I always scope the output of the circuit I am tuning then move to the next. Like in your diagram above I go to the output of L2, adjust then move to L3, ect.

I am basicly deaf in my right ear and only have 60% hearing in my left. So I trust my scope to adjust the signal rather than noise.

 

[2FB327]

Thank you very much, now I have two ways.
I'll pick up an analog meter next time I'm out.