Thursday, April 25, 2013

4o meter transmitter

My VHF has gone QRT and 20 meter set-up is not good for local contacts. This is a right time that i should opt for 40 meter with its inherent regional contacts. There are few newly licenced( Jan 2013)  gr-ii hams  in my neighbrouring cities so they will be happy to work in AM as first transceiver. There is a very simple and effective time proven VU2VWN transmitter.  But, i want to give it a twist by going for xtal cotrol. 7 Mhz xtals are not readily available but a 11.0592 and 4.000 Mhz xtal are ten a piece. so, will make a Premixed oscilator using TA7358 AP and rest is vwn transmitter. When it will be completed you can work me on Ancient Modulation, Charlie Willy, MCW on 7.059 Mhz ( +/- 5khz). I also will make a suitable AM receiver. Using my 4 Mhz designs. If my circuit works it will be a new begining of local AM in saurashta region like it was in south india a decade ago.

( 27jan2015 out of this ham most have vhf and enjoying the local city regchew. okey with me. But no one has the setup to talk to me 100km on VHF)

As of Jan2014 , Planning to revive the first build transmitter and gift it to another friend in the Rajkot for a demo and to come up on the air with AM. There was problem of the tuned ckt in the final bd139 amplifier. Now, i have the LC meter so can re-check it. It is xtal controlled on a signle frequency but will make 28.322mc and 14.318 mc and digitally devide it to get more frequency.(as suggested to me by VU3SXT-Sandeep Lohia)

I will be not able to work with it as my LRR40 never worked and sait 40 meter band is also not working.(finally SAIT gone qrth around the end of the nov2014, I regret I bought the marine receiver, instead of the Chinese imported radio)

vu3inj, first vwn40 tx

 This was my first experiments with the vwn tx. it produced lots of qrm around house as the antenna was not tuned and loading tank not proper so discarded it but will sure to make it work after tweaking the coil.  It should work.

on 27jan2015:-
This transmitter works but lacks power. Clean power is aobut 3watt after that it produce more QRM then RF. This fact was found out with the power meter and receiver. So calls for a linear. This will be made soon.

Will remove this old box and make a more air tight, fan cooled box to house  a new VFO using ceramic resonator, one xtal mixer using the gate , one 7159kc VXO. This gizmo will put the transmitter in multifrequency mode. Will aslso add RF indicators, TX-RX control relays etc.... and then gift it.......

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