# 10 MHz only WWW time signal receiver

#### atferrari

Joined Jan 6, 2004
3,957
I want to implement a receiver to get only the time signal from WWW (10 MHz). Proof of a concept is the goal.

Since it is not the main point in my project I am looking for a "sure fire" circuit not needing more than the usual debugging.

I run across one here: http://www.qrp.pops.net/wwv_receiver.asp

My questions:
A) Dual MOSFET 40673 transistors are discontinued ones, not obtainable locally and hard to get (time and ). Is it any modern one which I could use to replace them in the front end section?.

B) Regarding the ferrite toroids I have in my junkbox: how could I know if any one match the reccomended ones?

C) Is there any reason to use such an elaborate audio amplifier circuit or could it be replaced by something based on a audio amp IC?

D) Can anyone suggest another circuit, similar or SIMPLER, which I could build but "sure fire" granted?

Please do not propose alternatives other than RF receivers. Proof of the concept in play requires it!

(Yes I know that GPS exists. I really know that!) My RF practice is lost in time and have not time nor interest in experimenting. At least not this time.

Thanks for any help. I will certainly appreciate that.

#### mrmeval

Joined Jun 30, 2006
833
You will have to do some research but these are very close and seem to be current production. Look at the BF961
http://www.vishay.com/transistors-rf-af/dual-gate-si-mosfet/

This says you can use several as a replacement for the circuit listed but I'm not familiar enough with that style mosfet to know how well any apply to yours.
Q1 40673 Dual Gate MOSFET (obsolete) use
NTE222, BF981, BF961, or 3SK88

This fellow sells all that and at a good price it seems. But he has a minimum order which makes him less useful. He has the exact part for 5.98
http://www.angelfire.com/electronic2/index1/40673_dual_gate_mosfet.html
And a possible cheaper alternative
http://www.angelfire.com/electronic2/index1/bf981.html

#### SM5JAB

Joined Oct 1, 2007
5
Get a 10.000 MHz XTAL, use a toroid and two diodes as a balanced mixer between the antenna input and this XTAL-signal. Then amplify as h**l with a 741 (also neat for filtering) and finish off with a LM386 for audio power output. You should use a small cap i series with the xtal for fine tuning. This is a direct mixed receiver, often used in QRP-equipment.

#### SgtWookie

Joined Jul 17, 2007
22,210
Are your "junkbox" toroids color-coded?

Check out this site:
http://www.amidoncorp.com/aai_specifications.htm

There are dimensions and color codes listed in various subsections. You should be able to at least get an idea of the values of your on-hand items.

Note that you should discard any that have any nicks or scratches on/in them.