Re: TCXO Modifications


I found some Vectron C4550A1-0213 OCXO's on eBay. Looking at the published specs of a LOT of OCXO's, I find these have the best phase noise specs of any I have looked at. They are 5 volt units, SC-cut crystals (what you want) and an HCMOS square wave output. They reach stable temperature in about 5 minutes. Probably because they are so small.

I'm still experimenting with output circuits. I put a 10 MHz lowpass filter on the output of one. It makes a nice sine wave output. That may affect the low-frequency phase noise, though (jitter). They seem to do fine on 10 GHz but I haven't tried them with higher band transverters yet. I may try running the direct HCMOS output to my PLL circuits for all of my transverters.

73, Zack W9SZ

On Wed, Nov 10, 2021 at 6:07 AM Mike Kana <> wrote:
I disabled the onboard reference and did the mods. I’m experimenting with two OCXO:  one is a 5v vectron and the other is a 12v UCT double oven. No stability issues and able to net after 15 min initial warmup - I’m getting into the habit of powering the OCXO well in advance of operating so it’s ready to go. 
The UCT oscillators have been found NOS from a us seller on the auction site and I’ve  been retrofitting into my other transverters
73 Mike AA9IL 

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On Nov 9, 2021, at 8:37 PM, Mark - WB8TGY Korroch via <> wrote:


We have placed some of the thin plastic foam packing material around the TCXO on the board.  Beyond that, K2YAZ's and my stations are built inside a plastic Hammond box, with a hole saw used to drill the hole for the horn, and just small holes in the case for the headphones jack for the side tone, the jack for the key, and the jack for a microphone.  The inside of the box we stuffed a lot of fiberglass insulation around the PC board to help keep the wind from getting to the PC board.  I personally think it's stable enough for CW work with the GPS 1PPS turned off after a short "warm up" with it on.   I think K9PW  and KB8U would have liked it a bit more stable.  Maybe some day I'll try and modify this station or the other board I have to use a OCXO, but for now I'm fine with the way it works, and I'm not so sure I want to try modifying one of them.


On Tuesday, November 9, 2021, 06:28:28 PM EST, Doug Millar via <> wrote:

Hi, Thinking about CW contacts.  Does putting insulation around the internal TCXO stabilize the radio enough to do reliable CW? What insulation do people use?  Should you just go OCXO?  What are people's experiences?   Thanks, Doug K6JEY

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