10M AM Junkbox TX Part 2

Рет қаралды 2,565

Күн бұрын

As I completed the Power Supply and started the RF Wiring, I had a little issue with the 10 Meter AM Junkbox Transmitter.

Пікірлер: 36

@SpinStar1956 10 ай бұрын

Definitely enjoying the old-school build. I really wished when I was a kid that I would have hung out more with the HF-OM's instead of the repeater crowd! I think i'd have picked up much more 'real' useful knowledge... 73 Mike...

@MIKROWAVE1 9 ай бұрын

My elmer was a 75m SSB Net and Repeater guy who had to study to give me the code test for Novice! Naturally I rebelled!

@MrBtcruiser 10 ай бұрын

I remember purchasing a Uniden President HR-2600 10-meter mobile rig and a small base loaded mag-mount antenna during the 1990's solar maximum. One morning on my commute to work I checked into a UK net and talked for 20 minutes - solid copy both ways - completely blew my mind. I eventually sold that rig, but every solar cycle peak I wish I would have kept it LOL.

@MIKROWAVE1 10 ай бұрын

This one is shaping up to be a fantastic solar cycle, perhaps blasting the downward trend of the last 3.

@paulswift700 10 ай бұрын

Hi. Good to see you making a 10m AM rig. Over here in 6we can only use 28.1 to 28 15 for AM use. But sadly I have never heard anyone using it. Very sad. 10m over here is very quite. I have only made one contact from here on 10m and that was the first time I put up a wire dipole. Not made any contacts since. Keep up the good work. 73's. Paul. De HS0ZLQ, G0MIH.

@ornithopterindia 10 ай бұрын

👍Thank you for the video.

@Steve-GM0HUU 10 ай бұрын

👍Thanks for video Mike. A shame that the first transformer was no use. One thing I usually do with these old unknown transformers before applying power is give them a good sniff 😂. Very often, if they have been "cooked" as a result of shorted windings, there is a distinctive smell. I would describe it as slightly unpleasant sort of fishy smell. Looking forward to next installment and thanks again.

@MIKROWAVE1 10 ай бұрын

Good tip! Tip of your nose😊

@JCWise-sf9ww 10 ай бұрын

Mike for those looking for a new Hammond power Transformer, I found Hawk Electronics out of Chicago, IL; has the best pricing. That's where I bought one to restore an old Oscilloscope I bought from a Hamfest decades ago for $1. Scope was missing the power tranny. To make the very HV for the CRT, I made a tripler circuit fed off one of the 350v windings.

@MIKROWAVE1 10 ай бұрын

Paying 50 to 100 dollars for a tube power transformer is actually reasonable, considering the value of money today.

@CARL557511 10 ай бұрын

There is a tube I've been experimenting with in audio and rf application it is the 6jh5 high mu beam triode. Zenith brands work the best with around 450 to 500v for the b+. Hopefully when I get it done it will work on 40m am. Thanks for sharing your videos, love the vintage stuff! Carl, kc8ylt.

@MIKROWAVE1 10 ай бұрын

Playing with and applying specialized and odd valves and semiconductors in traditional amp architecture is a lot of fun.

@m0dad 10 ай бұрын

A pity about the transformer Mike. I`m told this is all part of the fun of building transmitters working through the problems or trying to find out why something is not working. Can also be very frustrating and costly at times. Cant wait to see this up and running. 73 M0DAD North East England.

@MIKROWAVE1 10 ай бұрын

Yes, when we utilize junk with an unknown past life, you always take a chance! But when I see these big guys on an old chassis or under a flea market table, I grab them. The perfect transformer exists for your project thanks to the audiophile demand. But plan on spending 50 to 150 bucks.

@ellise.2574 10 ай бұрын

I Mike. I always enjoy your Videos. What do you think about putting the choke in the negative DC return?

@MIKROWAVE1 10 ай бұрын

Yes. That is a good approach.

@W1RMD 10 ай бұрын

Looks like a great project! 10 meters has been awesome. I worked my first Hawaii ever (ssb) and I've been a ham for 30 years. Strange to here the W1AW code practice come in last night on 10 meters, and I live about 115 miles from you in Maine. I think the ARRL is about 225 miles from me. What kind of propagation is that? And at night also? Too far to be ground wave but too close to be ionosphere skip. I've heard a ham say yesterday that "10" is the real "magic band".

@MIKROWAVE1 10 ай бұрын

There are weird things happening on 10M. Echos, DELAYS, backscatter events and weird propagation!

@johnwest7993 10 ай бұрын

I like to test the transformer windings with a milli-Ohm meter before I do a voltage test. It gives me a little better idea of what to expect before I give it any juice.

@alainmichaud8992 10 ай бұрын

I had ambiguous readings like 0.2 and 0.3 Ohm while trying to find the taps, then I used a cheap $30 inductance meter. Then I got steady and disernable readings.

@Paul_VK3HN 10 ай бұрын

Thats a beautiful receiver Mike no obvious branding, what is it?

@MIKROWAVE1 10 ай бұрын

That is a Watkins Johnson 8711. My heart says that my R390A is better. But my head says the WJ is better. That said, I just blew out the preamp in it I think! Can't say that about the Collins!

@Paul_VK3HN 10 ай бұрын

@@MIKROWAVE1 wow, a $4k receiver, nice. Good luck with the preamp. Don't fancy doing that repair job myself. Make a video about it if you do.

@Skyler_Hagen 10 ай бұрын

I’ve always wondered about using a power transformer as a filter choke. Is there any concern with it saturating and reducing filtering (I.e. increasing hum) at higher DC load? I had always thought that true purpose built “chokes” used gapped cores to avoid saturation (within their DC current rating at least.)

@MIKROWAVE1 10 ай бұрын

Yes and Yes, but some useful inductance is better than none, and this is low brow design using what is on hand. Generally, the current capability and insulation of a primary winding is good, but fully isolated (plastic sepatated) windings helps at higher voltages.

@Skyler_Hagen 10 ай бұрын

@@MIKROWAVE1 that’s good to know! I suppose if you were really on a budget you could pull the interleaved EI laminations out of a power transformer and reinstall them non-interleaved to form a better choke! I’m all for doing things on a budget.

@gunterkonig959 10 ай бұрын

Many thanks for the nice Video. 73 DJ8CY

@MIKROWAVE1 9 ай бұрын

Thanks for watching! Done for 2023. Nice to wrap up a project.

@delmerleynaud7424 10 ай бұрын

Hello Mike. At 10:40 minutes of your video, you mention tubes tested. If 6HA6 is a tube that could have been tested, it is a 9-pin tube and all the others are 7-pin. You probably have tested a 6AH6, that fits more to this application. Kind regards, Delmer LU1FDQ

@MIKROWAVE1 10 ай бұрын

Yes 6AH6. The 6CL6 multiplier is working now. I tried a 39K resistor and a 100uH choke in the Plate of the oscillator. They both work, but the choke almost doubles the Vpp swing out of the multiplier.

@delmerleynaud7424 10 ай бұрын

Thanks for ur answer. @@MIKROWAVE1 Probably the 39K resistor drops the anode DC voltage too much. 6BA6 must be working @ 5 mA anode current; if so, drop voltage would be around 200 V. A 100uH choke would self resonate around 5 to 7 MHz, isn't it? I everytimes found very difficult to calculate (not measure) the self resonance of a coil. Kind regards.