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 AM Radio Transmitter
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 Return to top of page · Post #: 1 · Written at 4:11:17 PM on 11 September 2020.
Fred Lever's Gravatar
 Location: Toongabbie, NSW
 Member since 19 November 2015
 Member #: 1828
 Postcount: 917

Guys what is the latest go re buying or making a kit like the SC low power device March 2018.

Is any member offering a kit?

I have my valve based Transmitter but really I want to set up a 24/7 PCB inside a existing DAB radio to convert DAB 2CH to AM.
Then I can leave all the AM radios in the house and workshop right where they are to listen to 2CH via a wire antenna.

Fred.


 
 Return to top of page · Post #: 2 · Written at 4:43:23 PM on 11 September 2020.
Johnny's avatar
 Location: Hobart, TAS
 Member since 31 July 2016
 Member #: 1959
 Postcount: 429

The HRSA transistor kit is still available.
And gives excellent results.
JJ


 
 Return to top of page · Post #: 3 · Written at 5:20:01 PM on 11 September 2020.
Ian Robertson's Gravatar
 Location: Belrose, NSW
 Member since 31 December 2015
 Member #: 1844
 Postcount: 1981

Fred, I have some bare PCBs that I had made for a synthesised AM transmitter, intending to fit one of those Chinese media player / FM tuner modules in the same box. I also have all the parts.

It uses an LM13600 for level compressor and modulator, followed by a chip that drives the antenna. (The design is capable of more power than is legal so this may need to be cut back). It has a simple PLL based on a 4046 and some CMOS logic. Frequency is set by a dipswitch. It's all, or mostly, thru-hole from memory.

What I don't have is the time to put it together, but SC have expressed an interest in it once it's a working prototype.

Would you like to take it on?


 
 Return to top of page · Post #: 4 · Written at 8:57:12 PM on 11 September 2020.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6142

If you want a valve-based AM TX, this is the one that I and some others on here use:

https://www.6v6.co.uk/vcomp/pages/itxkit.htm

At the time I purchased mine, I also bought their power supply:

https://www.6v6.co.uk/vcomp/pages/bateliminator.htm


 
 Return to top of page · Post #: 5 · Written at 9:15:25 PM on 11 September 2020.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 4460

Interesting that they fused the HT on their battery eliminator and put a thermal trip on LV. I put the same on the bench PSU heater / filament windings & a HT fuse.


 
 Return to top of page · Post #: 6 · Written at 12:26:03 AM on 12 September 2020.
Ian Robertson's Gravatar
 Location: Belrose, NSW
 Member since 31 December 2015
 Member #: 1844
 Postcount: 1981

Hmmm. Sounds about as stable as New Zealand!


 
 Return to top of page · Post #: 7 · Written at 7:40:23 AM on 12 September 2020.
Fred Lever's Gravatar
 Location: Toongabbie, NSW
 Member since 19 November 2015
 Member #: 1828
 Postcount: 917

Ian that sounds interesting.
Can you mail the bits to me and I'll have a go at sticking it together?
Fred.


 
 Return to top of page · Post #: 8 · Written at 9:39:47 AM on 12 September 2020.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 4460

Forgot, The idea of the PSU fusing is that it gets used on some interesting things, radios that are faulty & you are using it to try & find it. The reformer regulator will "lock up" on overload.

The principal objective is to save the PSU transformer. HT itself can be regulated via a 6L6. Reformer relies on its LR8 & bypasses the other entirely valve regulator.

Marc


 
 Return to top of page · Post #: 9 · Written at 11:14:12 PM on 12 September 2020.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 4460

If the platter turns consider yourself fortunate. There was one BSR turntable, and I have actually had the displeasure of getting one, where the lubricant used welded the platter bearing to the shaft. I thought it unbelievable when I read about it. Swift change of mind. Hell and damnation was never going to move it.

Examine carefully. Many of those platters run on a removeable roller race. It does pay to get it out. The grease soap may not have gone hard but it will likely be full of fretted material and you need to get it all out before using new. Philips used Shell Alvania 2 in some stuff. I think perhaps too heavy in a turntable?

Shell name change: https://shell-livedocs.com/data/published/en/61c79668-557a-4237-a6bd-8517542f49c5.pdf
Similar: https://www.inoxmx.com/products/mx8-extreme-pressure-grease/

Soft grease food grade (I use mx6) https://www.inoxmx.com/applications-and-uses/electrical/

Oil: Do not use engine oil on anything: It is designed to scavenge water and will take it out of the atmosphere.

Marc


 
 Return to top of page · Post #: 10 · Written at 11:55:55 PM on 12 September 2020.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6142

^ wrong thread.


 
 Return to top of page · Post #: 11 · Written at 8:22:21 AM on 13 September 2020.
Fred Lever's Gravatar
 Location: Toongabbie, NSW
 Member since 19 November 2015
 Member #: 1828
 Postcount: 917

Re post#5 #8 and #9.

Hey Marc! I thought I was the only one here that has "senior moments" !!!

Cheers, Fred.


 
 Return to top of page · Post #: 12 · Written at 9:42:03 AM on 10 October 2020.
Jimb's Gravatar
 Location: Kanahooka, NSW
 Member since 18 November 2016
 Member #: 2012
 Postcount: 710

Just to add to Johnny's comment for anyone else planning one . The kit supplied by HRSA works very well. It is one of the 3 I have and now is the most used I run it on AA batteries and they last for months. Regards Jim


 
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