Aligning frequency without the equipment.

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original45
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Aligning frequency without the equipment.

Post by original45 » 25 Jun 2018, 19:05



Had a few little problems with my recent purchase the Formac 120.

Mostly switches,scratchey ptt and a disconnected bleep all now rectified.

So today I asked for a couple of radio reports and all stated I was off frequency.
Those closer contacts could understand me as I them .but further away signals that I would normally hear very well and perfectly clear sound slightly off to me also and a kind of paced ticking faintly.

Stuck another radio on and theirs Def a differance in the clarity of audio.
Listening to myself on a radio in the room it sounds fine .

It seems to be only the uk fm side too .

Is their any way I can align the fm frequency without the technical equipment.
Maybe by listening to the rx signal ?.
Thank you

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ch25
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Re: Aligning frequency without the equipment.

Post by ch25 » 25 Jun 2018, 19:17

When I'm too lazy to get my freq meter from the shelf I tune radios listening myself on my HF rig. Verification shows, that I can achieve 50Hz accuracy by ear. But I have years of practice :)
Chris
You can't have too many antennas...

original45
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Re: Aligning frequency without the equipment.

Post by original45 » 25 Jun 2018, 19:46

I do have a keen ear but 0 experience.

Is it a complex procedure Chris or it it a matter of may be one screw in a variable pot very slight adjustment.

Would you happen to know which pot it is on the formac 120. Would it be on the small fm board or on main board .

26TM5890
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Re: Aligning frequency without the equipment.

Post by 26TM5890 » 25 Jun 2018, 20:09

50 Hz is still too much for SSB

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ch25
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Re: Aligning frequency without the equipment.

Post by ch25 » 25 Jun 2018, 20:12

Not really considering chickenbanders swimming +- 300Hz cold to warm :)
AM/FM unnoticeable, SSB depends on ambient temperature :)
You can't have too many antennas...

Kaliphan
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Re: Aligning frequency without the equipment.

Post by Kaliphan » 25 Jun 2018, 20:32

ch25 wrote:
25 Jun 2018, 20:12
Not really considering chickenbanders swimming +- 300Hz cold to warm :)
AM/FM unnoticeable, SSB depends on ambient temperature :)
The alignment tolerances on some of the old SSB CBs is about that much :D

He could check the Formac by listening to it on an SSB set but if it's only off on 27/81 it's probly off by a mile because it'll have been set by ear and done half arse

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dt307
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Re: Aligning frequency without the equipment.

Post by dt307 » 03 Jul 2018, 13:46

ch25 wrote:
25 Jun 2018, 19:17
When I'm too lazy to get my freq meter from the shelf I tune radios listening myself on my HF rig. Verification shows, that I can achieve 50Hz accuracy by ear. But I have years of practice :)
Chris
guilty as charged as well i do the same .

ive played a 1k tone from a smart phone into the mic on say 27.565 usb and lsb the resulting output will be exactly 1k higher on usb and 1k lower on lsb ..this also works fine and within a few hz.

it makes little difference unless some one has the radio on for exactly the same time and the radio has reached the axact same temp the milage going to be different.
163dt307-chris




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Black Spirit
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Re: Aligning frequency without the equipment.

Post by Black Spirit » 03 Jul 2018, 14:16

As i stated before, Add a 56pf capacitor across the 33pf thats next to the high band crystal trimmer, This will bring high band down to almost exactly the UK offset

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