Macgregor kit....

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Re: Macgregor kit....

Postby ronstv » Sat Jan 28, 2017 9:40 pm

PM received.

Thanks.

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Re: Macgregor kit....

Postby dodgy » Tue Jan 31, 2017 3:06 pm

Supermac received OK! Thanks a bunch!

Since wires are cut off, it will need a new aerial - I assume one cut to a similar length as the SuperMac relay I have will be reasonable for testing?

I would like to get the relay receiver I have working by taking spares from the donor relayless receiver - but I will start by checking the relayless works first. The output has a similar green/purple/blue to the relay receiver - can I check these by putting a resistance meter against them in the same way as I would check relay contacts?
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Re: Macgregor kit....

Postby dodgy » Thu Feb 02, 2017 1:12 am

Well, my Supermac relay receiver still functions by throwing the relay the minute power is applied, and then the relay drops out when the transmitter is turned on. Keying the tone has no effect.

I suppose I need to start troubleshooting by understanding the circuit (Ha - fat chance!). So does anyone have a circuit diagram for the Macgregor Supermac receiver? If not, I will try the laborious method of recreating the schematic by looking at the PCB...
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Re: Macgregor kit....

Postby Phil_G » Thu Feb 02, 2017 2:16 am

Did you try the suggested checks with your domestic radio Chris? You're certain the transmitter is actually emitting carrier and modulating it with tone?
And you're certain the receiver L/O is running? and that its the right freq for the IF? These are all tests that can be done without desoldering anything...
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Re: Macgregor kit....

Postby dodgy » Thu Feb 02, 2017 1:21 pm

Phil,

Using your S/W trick I was able to select a spot where the static was suppressed when I turned the Tx on. At that point, when I keyed the Tx, I heard a faint 1khz tone. So I think the Tx is working. There was quite a lot of 'body capacitance' effect, of course, but I could get a tone at least 30ft away.

I tried your trick for the Rx on MW, with a wire aerial laid on top of the Rx cans. Yes, I could find a spot where, with the Tx on, I could get a definite whistle on the radio which went on and off as I applied power to the RX, or the Tx. Both the Supermac Relay and the Relayless circuit that Ronstv so kindly sent me make this noise.

Whether the frequency is correct is a difficult thing to say. There was so much drifting and body interaction that I can't give a ready estimate of the tone I heard. But the relay Supermac does seem close to functioning. It now reliably powers the relay continuously on when I connect power to it, and drops power to the relay when I turn on the Tx. Keying the Tx tone produces no effect.

Interestingly, the Rx only throws the relay if I power it on and don't touch the battery case. If I touch it, the relay drops out. Body issues again...
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Re: Macgregor kit....

Postby dodgy » Thu Feb 02, 2017 5:26 pm

Well...

I thought it would be a good idea to test the relayless Supermac, so I set up a little 3v circuit with an LED and connected it to the Rx output as per the Macgregor instructions on the site archives.

As soon as the Rx was powered up, the light came on. And when the Tx was turned on, the light went out. Keying the tone had no effect.

This is behaving exactly the same as the relay Supermac - the Rx provides an output as soon as it is turned on, and stops providing an output when the TX is switched on. Near enough the opposite of what should happen...

I think I have two sets intended for the Australian market...
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Re: Macgregor kit....

Postby Phil_G » Thu Feb 02, 2017 5:32 pm

dodgy wrote:...I was able to select a spot where the static was suppressed when I turned the Tx on. At that point, when I keyed the Tx, I heard a faint 1khz tone.
If the static is fully quieting then you should hear a strong tone, its almost 100% modulated. Could it be the tx?
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Re: Macgregor kit....

Postby ronstv » Thu Feb 02, 2017 6:18 pm

Try tuning an fm radio to approx 108mhz (4times the tx freq) with tx switched on. The loud fm static should fully quieten. Key the button and the tone should be really strong. If not I would hazard a guess that there is a problem with the tx

Ps if you can use brown crystals (26.995)MHz it keeps it within an fm radios band width 107.98mhz

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Re: Macgregor kit....

Postby dodgy » Thu Feb 02, 2017 6:44 pm

108Mhz is a lot easier than the earlier 9khz....

I tried, with the aerial 1/4 up, and found that the static was only half-depressed, and the tone, though heard, was fairly lost in it. Then I tried with a full aerial, the static completely went away, and the tone came through quite clearly. I think the Tx is fairly Ok - though a new aerial would probably be a good idea. The sliding parts may not have good contact....

The relayless Rx is behaving in exactly the same was a the relay Rx. Initially it had a solid 'output ON' when I powered it up, and a solid 'output OFF' when I turned on the Tx carrier. This worked reliably over 100ft or so (the furthest I could easily test)

As I left the relayless Rx powered up for an hour or so, it started to jitter and then turned off. It's sensitive to my presence now, turning on when I get a few feet away. I suspect the capacitors are all varying quite a lot as power flows through them...
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Re: Macgregor kit....

Postby ronstv » Thu Feb 02, 2017 6:48 pm

Tx aerial?
I think I may have one in good condition

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