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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment. |
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22nd Nov 2022, 9:43 pm | #1 |
Tetrode
Join Date: Jul 2018
Location: Southport, Merseyside, UK.
Posts: 63
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Crystal assembly
I have had this block of 6 plug in crystals in my bits box for many years.
I finally got round to plugging them into my ct432 calibrator and cheapo Chinese counter. they read from 148.500 to 152 .250 kHz spaced 750 Hz apart. I vaguely remember that it came out of a piece ex gov gear that I bought from a radio junk shop on London road in Manchester many years ago and dismantled as I did then.I think there were quite a few ef50s in there as well. just out of curiosity I wonder if anyone knows what the item's function was, Some sort of radar unit?
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22nd Nov 2022, 10:09 pm | #2 |
Dekatron
Join Date: Nov 2006
Location: London, UK.
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Re: crystal assembly
So that’s on the long-wave spectrum.
Maybe from an old transmitter? Far too low f for radar IF.
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Al |
22nd Nov 2022, 10:13 pm | #3 |
Banned
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Re: crystal assembly
Could be a filter system. 750 Hz passband plus or minus.
Joe |
22nd Nov 2022, 11:51 pm | #4 |
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Re: crystal assembly
+/-750 Hz would imply a 1.5kHz wide filter.... not bad for RTTY, and in government equipment that would seem to fit
A filter for teleprinter mode from some system with a 150kHz final IF seems possible. David
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23rd Nov 2022, 6:38 pm | #5 |
Nonode
Join Date: Nov 2015
Location: Welwyn Garden City, Hertfordshire, UK.
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Re: crystal assembly
They don't look big enough to be that low?
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23rd Nov 2022, 9:40 pm | #6 |
Octode
Join Date: Nov 2010
Location: Ross-on-Wye, Herefordshire, UK.
Posts: 1,648
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Re: Crystal assembly
I'm thinking of a radio navigation unit like one of the GEE or GEE-H variants. This sort of crystal would be used as a timebase for the timing function - and ultimately determine the accuracy of the radiolocation offered.
As far as I can recall the basic GEE Mk.II system started from a 150kc/s crystal and divided it down in the Indicator unit. Richard |
23rd Nov 2022, 9:53 pm | #7 | |
Dekatron
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Re: Crystal assembly
Quote:
Link from VMARS here and close-up of the relevant page. 100V P-P sine wave from that stage, photo top left. http://www.vmarsmanuals.co.uk/archiv..._GEE_MK.II.pdf
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23rd Nov 2022, 9:57 pm | #8 | ||
Octode
Join Date: Nov 2010
Location: Ross-on-Wye, Herefordshire, UK.
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Re: Crystal assembly
Quote:
Well, I think I am on the right track. But GEE Mk.II had a single 150kc/s crystal. What we have here is a set of crystals carefully spaced around the 150kc/s point. I am thinking - speculating - that this is part of a later coding system (to fool enemy jamming perhaps). And the crystal types make me think 1950s, so perhaps we are looking at GEE Mk.III, which I have never really paid much attention to. Richard |
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23rd Nov 2022, 10:01 pm | #9 | |
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Re: Crystal assembly
Quote:
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Al |
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23rd Nov 2022, 10:22 pm | #10 |
Nonode
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Location: Tintinara, South Australia, Australia
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Re: Crystal assembly
One of the crystals does have APR 56 marked on it so that might be an actual date - either crystal manufacture or installation date.
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23rd Nov 2022, 11:18 pm | #11 |
Dekatron
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Re: Crystal assembly
Well spotted Terry.
Here’s the cct. showing the X-tal oscillator that is used to generate sync pulses
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Al |
23rd Nov 2022, 11:59 pm | #12 |
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Re: crystal assembly
Look inside your watch. There's a variety of crystal modes other than SC cut face-shear.
David
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24th Nov 2022, 12:41 am | #13 |
Dekatron
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Re: Crystal assembly
Just noticed x-tal osc. photo didn’t upload. (#11) Here it is
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Al |
24th Nov 2022, 1:33 am | #14 | |
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Re: Crystal assembly
[QUOTE=trh01uk;1515924]
Quote:
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24th Nov 2022, 11:31 am | #15 |
Octode
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Location: Carmel, Llannerchymedd, Anglesey, UK.
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Re: Crystal assembly
I fondly recall GEE as I used to live a couple of miles from a tx at Worth Matravers. It sang away at 30.7 Mc/s and spread all over the band. A handy calibration reference!
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25th Nov 2022, 1:51 am | #16 |
Dekatron
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Re: Crystal assembly
Mazel Radio.
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25th Nov 2022, 12:12 pm | #17 |
Nonode
Join Date: May 2007
Location: Preston, Lancashire, UK.
Posts: 2,510
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Re: Crystal assembly
I believe Richard has cracked it. I just checked the circuit of the GEE Mk3 Indicating Unit Type 26, and that has a module containing six crystals all arounf 150kHz.
Andy |
25th Nov 2022, 8:42 pm | #18 |
Tetrode
Join Date: Jul 2018
Location: Southport, Merseyside, UK.
Posts: 63
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Re: Crystal assembly
So it looks like it was gee equipment, I thought it was possibly airborne gear as it had a higher frequency power transformer in it. thanks for all the interest in this. Regarding Mazel radio, no, it came from a small shop further up. I don't think he lasted very long. I actually worked for Mazel from the early 60s to early 70s
Heres a pic of the shop,all gone now.JAK was the son of his lady friend he moved to Southport and I followed him and worked for him for some time doing repairs. I kept in touch with him until he passed away earlier this year, His grandson now runs his shop. The pic won't load up, will investigate what's wrong and put it up later.
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25th Nov 2022, 9:02 pm | #19 |
Tetrode
Join Date: Jul 2018
Location: Southport, Merseyside, UK.
Posts: 63
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Re: Crystal assembly
Now got the pic to load up
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