Ham Radio - The 630 meter CW transmitter part 4. It's done and it works!

This has been one heck of a project. It's finally done. The link below will take you to the blog post where there's a complete write-up of the project and links to all the files you'll need to build your own.
kb9rlw.blogspot...
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[@DonDegidio]

Hi Kevin, Looks great. The illustration of the straight key on the label is a nice touch. Looking forward to the on air tests. 73 WB3BJU

[@m0dad]

Excellent video Kevin and a very inspiring project. Well built and neat looking transmitter. Great explanation. 73 and best wishes from north east England.

[@dalemyers5096]

I would opt for a 12 foot diameter mag-loop antenna. Cause it's 630 meter and with antennas, the bigger the better. And as always,,, you can run multiple wire loops around in that circle from one stand of wire. I've contemplated using pvc pie and copper tape to make a copper cactus antenna. I might use that technique to make a magloop, to save money. If not tape,, then a foil.

[@bklynhubby]

Hi Kevin. I don’t know cw, but this is something I would buy if I did. Congratulations! 73s. K2PDR.

[@rickeaston3228]

I think if I was to make a transmitter for 630 meters, I would probably use a converter that converts 80 meter signal with a mixer to 630 meter frequency. I think it would be much easier and get more power.

[@loughkb]

Transverters have to have their own power amplifier. You can only drive them with a few hundred milliwatts. You actually need to attenuate the output of the radio transmitting on 80 or you'll blow the transverter.

[@mrkattm]

Nice job, I wished more people built stuff, it seems like most folks just want to buy a signal these days. Thanks for sharing

[@5x9withQSB]

Wow Kevin I've really enjoyed watching you build this .congratulations! vk3ae.

[@urielamari170]

A trick: you can watch series at flixzone. I've been using them for watching all kinds of movies during the lockdown.

[@joshuaarthur3151]

@Uriel Amari Yea, have been using flixzone} for months myself =)

[@kylereric9711]

@Uriel Amari Yup, been using flixzone} for since december myself =)

[@malcolmdenver8328]

@Uriel Amari definitely, have been using Flixzone} for since november myself :)

[@joewilson2258]

Hey Kevin I am working on an inverted diamond five band quarter wave antenna for field communications . The bands are 40 m , 20 m , 17 m , 12 m , and 10 m , with 16 17ft ground radials . Can you give me some thought on my design ? I am using 2 inch to 1.5 inch pvc pipe for the main mast of the antenna with four radials for the 20 ,17 , 12 , 10 meter bands . I am also using a 5 way tee for the top with eye bolts for the draw cords to draw up the wire elements . For the main 30 feet of the central mast I am using 2 inch pvc and the top will either be 1.5 inch or 1 inch pvc pipe of 4 feet 6 inches the lower sections will be 40 inch sections so I can transport it to any location .

[@caulktel]

Great video Kevin. Which MOSFET did you end up using?

[@loughkb]

One of the IRF510's you sent me. Thanks again!

[@n8nkqrp595]

Nice xmtr Kevin. Hard sounding keying which i love! Makes a diff when using QRP. I'd love to see you show us the RF keying envelope. Ignorant question now- on 630 meter CW, is QRP not limited to 5 watts like the commonly accepted power output level on HF? Thanks for the interesting series!

[@loughkb]

The keying only sounded harsh because the receiver was so close. That little Grundig doesn't deal well with strong signals. It's actually very clean sounding over the air. We are limited to 5 watts EIRP. Radiated power at the antenna. Since the antennas we can manage are incredibly inefficient, you could probably drive 60 watts in and still radiate less than 4.

[@n8nkqrp595]

I meant the keying characteristics were desirable - at least for me with my 59 year old hearing. Regarding the output power of QRP I disagree with you. You are correct in that the allowed limit is measured in EIRP. Since you cant know your anttenna one-direction gain - without extensive in-field analysis - EIRP cannot be calculated by you. That doesn't mean that you can arbitrarily choose to drive 60 watts into the transmitter end of the feedline and still (1) assume that you would still qualify as QRP and 2) to do so but with a higher arbitrary pwr level of your choosing - could result in illegal operation. Kevin - with all due respect (because of your very good vieos that we all enjoy) in the real world, one measures their power output at the feed point of their feedline. Every QRPer I know does this. I bet every member of my favorite club (NAQCC with 9000+ international members) does as well. Want more power delivered to the antenna? lower feedline loss. Ideally use open wire ladder line. Do what you can to make a decent antenna. It's surprising how efficient simpe wire antennas can be in their favored direction! Again - nice work on the videos. A lot of work they are, I'm sure. Thanks

[@BEdmonson85]

I always thought you calculated RMS voltage from peak to peak by multiplying 0.707*Vp2p. Am I wrong in this?

[@BEdmonson85]

Doh, nevermind, I just remembered (or maybe googled, hi hi) It's Vpeak*0.707 (not peak to peak). Glad you jogged my memory on that one.

[@flexairz]

To be even more precise.. its Vpeak times (1 / SQRT 2) But that is splitting hairs.. ;-)

[@BEdmonson85]

flexairz, indeed

[@DAVIDGREGORYKERR]

Would a VN66AF not worked as the driver and the final power stage as I have seen them used at 27.60125-27.99125mhz

[@loughkb]

No, that transistor has a 1 watt max power dissipation according to the datasheet.

[@DAVIDGREGORYKERR]

I meant that a VN66AF would work as a driver and a higher power VMOS transistor should work as the output stage.

[@loughkb]

It would be overkill as a driver. And you did say, "driver and the final power stage". ;-)

[@RobertAhrens52]

This my be wrong, but I thought that using the bnc-t would halve your power. No?

[@Jimwill01]

It would if the impeadances were equal. But, the scope should have a very high impeadances compared to the 50 ohm dummy load.

[@loughkb]

No, That would be a crazy amount of loss. Where'd you get that idea? BNC loss is in the range of 0.1 to 0.2 db according to amphenol's spec sheet. And that's at 3Ghz. It would be less at lower frequencies. Even at 0.2db, that's around 4% of your power, or less.

[@RobertAhrens52]

J. Williams thank you. That explains my error. I was not concerned about Insertion loss, but I was thinking of it as a signal splitter. Which of course would use similar impedance devices.

[@loughkb]

Oh, I thought you were talking about the antenna connector on the TX itself. I'd never heard anyone say half insertion loss, so I was surprised.