Tuning Slugs

[Tallman]

I used to work for a radio manufacturer a long time ago and when we had a radio that would not tune up because the inductors were too sensitive we had slugs that we could change out. These slugs were made of different magnetic materials or doped that would make the inductors less twitchy during alignment. Does anybody know it these are available for purchase? I have a radio that is so twitchy turning the slug a very, very small amount will jump 100's of Hz. Frustrating when you are going for maximum resolution on the frequency counter. On a 12 digit counter an updated reading can take ten seconds or more.
Any help is appreciated.
Tallman

 

[Robb]

I have a similar problem like this; so much as breathe on it and it moves 100hz.

Waiting for some solutions too.

 

[sp5it]

In Poland I heard about those ferromagnetic material types used for 7x7 filters.
F-605/u=600 - white
F-82/u=80 - violet
U-31/u=30 - orange
U-11/u=10 - gray
u - magnetic permeability
Mike

 

[Beetle]

I thought this was going to be about making something like a xylophone out of slimy garden pests, and how to adjust the pitch of each individual gastropod.

But it seems I was mistooken

 

[Robb]

I thought this was going to be about making something like a xylophone out of slimy garden pests, and how to adjust the pitch of each individual gastropod.

But it seems I was mistooken

For example, the 6900 series Galaxy boards have a drift problem, and have been trying to turn that situation around for some time. The loop osc coils are waaaay too sensitive to adjust. If knew what to change them out with to see less freq change per single turn, I'll bet that part of this drift problem will change for the better. Just a guess, but it seems logical and worth the effort. A single turn changes freq by ~500hz or more. How can I gauge permeability of the ferrite slug - other than putting them in the radio? Must be some kind of test?

I would sprinkle salt on them if I thought it would help - lol . . .

 

[Tallman]

I have a similar problem like this; so much as breathe on it and it moves 100hz.

Waiting for some solutions too.

You must have a Galaxy radio on your bench. I use to be a Galaxy fanatic but tuning one of those is just like :bdh:. The one I have I have been through it so many times doing the adjustments I have almost decided to scrap it. I had it tuned to within 5 Hz of the desired frequencies and put the lids on it jumps way off frequency. Inspected all solder joints and touched up the one that looked a little dodgy. I am going to replace U3 to see if that fixes it.

 

[Tallman]

In Poland I heard about those ferromagnetic material types used for 7x7 filters.
F-605/u=600 - white
F-82/u=80 - violet
U-31/u=30 - orange
U-11/u=10 - gray
u - magnetic permeability
Mike

That is the information I was looking for. Can they be had here in the states?

 

[Captain Kilowatt]

Usually in a case like this it is because of a poor L/C ratio in the tuning circuit. A very small value of C means that the tuning range is VERY broad and touchy when tuning the L. It works the other way around as well when too much L is used making the tuning caps very touchy. Somewhere in the middle is an optimum ratio of L to C.

 

[Robb]

Usually in a case like this it is because of a poor L/C ratio in the tuning circuit. A very small value of C means that the tuning range is VERY broad and touchy when tuning the L. It works the other way around as well when too much L is used making the tuning caps very touchy. Somewhere in the middle is an optimum ratio of L to C.

Those are 10 good reasons.
How can you tell if it is too much L or C?
IOW- total C of the loop osc circuit to what ratio of L in the same circuit?

EDIT:
Series C vs series L?

 

[CbRadiosPRONTO]

Tallman. What kind if freq counter are you using? I have a VC as my backup and yes, 10 seconds is the gate time if you're reading in the 10hz range .00001. Its a pain. The counter is dead on but the wait was excruciating. I replaced it with an HP.
Also, 12 digit counter??? How many digits are to the right of the point? There's no sense in going more than 5.

 

[AudioShockwav]

There's no sense in going more than 5.

Really?




73
Jeff

 

[Captain Kilowatt]

Also, 12 digit counter??? How many digits are to the right of the point? There's no sense in going more than 5.

Don't ever tell that to a REAL bonafide bench technician. I mean guys that service comm gear for a living especially commercial gear.Five digits is just ballpark to them.....I mean us....I mean me.....I mean...........

 

[sp5it]

100Hz resolution is good enough for chickenband.
Mike

 

[jazzsinger]

Tallman. What kind if freq counter are you using? I have a VC as my backup and yes, 10 seconds is the gate time if you're reading in the 10hz range .00001. Its a pain. The counter is dead on but the wait was excruciating. I replaced it with an HP.
Also, 12 digit counter??? How many digits are to the right of the point? There's no sense in going more than 5.

there's an infinite number to right of point as there is to left, but i'd say you need at least 8 digits on frequencies below 99 Mhz,so you have at least 6 on right hand side of point to read to 1Hz, but there's nothing stopping you being even more critical, just ain't worth it for a CB, but I'd imagine in some instances its very critical to go to much smaller fractions of a Hertz.

As for drift Robb, you ever considered it might not be the external components, but the oscillators, crystal load capacitance that is making it so touchy, it's been noted the radios (export anyway) that slide the most drift the most too, and crystal load capacitance plays a big part on how much effect components round it affect it. Just a thought for you. Temperature plays a big part too.

 

[CbRadiosPRONTO]

When I said 5, I was talking 5 to the right if the decimal so 10hz. If my optima is on LSB 27.51501 instead of 27.51500, nobody will be able to tell.


CbRadiosPRONTO