Alignment Advice.

[Yorkie]

Anyway this is way off base for the forum, we will soon get complaints and I can understand why , email if you want to discuss further.

You won't get complaints on this forum about going off topic PB, but there sometimes does come a point, such as with this thread, where it's best to perhaps start a new thread in 'The Lounge' or 'General Chat' with a more relevant heading. It's not in the nature of this forum for moderators to kill off-topic posts or to flit around like a virtual Mary Poppins or Mrs Doubtfire with a feather duster, tidying up and shifting stuff around, as though hankies have been put in the sock drawer.

[Skywave]

All points noted - and agreed with; for myself, my curiosity has been satisfied √.
Thank you PyrusBoy for your replies. And thank you to the moderating team for letting this thread drift way off topic as it has done.

Al. / Nov. 26, 2012 //

[AlanBeckett]

.. as though hankies have been put in the sock drawer.

That's where mine live

Alan

[boiss]

Back on Topic, how did the alignment go?
I am interested in a simple way to do the IF alignment, ie. some sort of
simple sweep or wobulator without having a pucker sig gen.
For fixed frequencies I use radios relying on the LO as the source (and also the radios own LO after having checked the IF frequency) and check the frequencies using a Sony ICF 7600. However maxing the IFs is usually the only thing possible (AM).
Cheers
Mike

[Joe]

After making the dummy aerial and a coupling loop I've never actually got on with it so thanks for the reminder. As I only listen to strong stations on it Id forgotten all about it.

- Joe

[Joe]

Following the timely reminder I got on with this this afternoon.

The IF seemed to be OK but using my loop I found that the RF was a bit out.

It still seemed pretty poor. Absolute Radio and Radio Sheffield were fine but apart from that all I could get was a barely audible Five Live with the volume full up. I therefore started to look elsewhere.

I'd previously changed most of the caps and only two original elecyrolytics remained: Trader Sheet numbers C13 and C23. Despite C13 being listed as 0.1µF both these are in fact 8µF.

C23 had an ESR of 10Ω so I changed that. This made no difference which I hadn't expected as I thought the problem would be further back in the circuit than that.

C13 had an ESR of 2Ω but neither a new one nor having none at all fitted made any odds.

When I got this set the ferrite rod was snapped and, as I hadn't got a replacement I'd spliced it.

Since then I have acquired bits so changed that which finally brought about a worthwhile improvement.

It still isn't great but having never had a comparable set in A1 condition it's hard to tell. Some radios, like Melody Makers and Bush VHF61s on AM, are just plain poor by design. It isn't fair to compare it with more modern or sophisticated sets and I'd say it's now about on a par with a DAC90a.

[Joe]

Following the timely reminder I got on with this this afternoon.

The IF seemed to be OK but using my loop I found that the RF was a bit out.

   

It still seemed pretty poor. Absolute Radio and Radio Sheffield were fine but apart from that all I could get was a barely audible Five Live with the volume full up. I therefore started to look elsewhere.

I'd previously changed most of the caps and only two original elecyrolytics remained: Trader Sheet numbers C13 and C23. Despite C13 being listed as 0.1µF both are in fact 8µF.

C23 had an ESR of 10Ω so I changed that. This made no difference which I hadn't expected as I thought the problem would be further back in the circuit than that.

C13 had an ESR of 2Ω but neither a new one nor having none at all fitted made any odds.

When I got this set the ferrite rod was snapped and, as I hadn't got a replacement I'd spliced it.

   

Since then I have acquired bits so changed that which finally brought about a worthwhile improvement.

It still isn't great but having never had a comparable set in A1 condition it's hard to tell. Some radios, like Melody Makers and Bush VHF61s on AM, are just plain poor by design. It isn't fair to compare it with more modern or sophisticated sets and I'd say it's now about on a par with a DAC90a.

It's certainly plenty good enough as Absolute is the only MW station I listen to.

- Joe

[Skywave]

Hi Joe,
It's good to see that you are making some progress with that set. Having read what you have written, a couple of thoughts have crossed my mind.

(i). Although I have never attempted a repair to a cracked ferrite rod - as per your post - I have heard stories of people who have and I do understand the basics of magnetic circuits. The golden rule is that whatever is used to join the two pieces, the non-magnetic gap must be very small. My first recourse would be to use 'Superglue'. What adhesive did you use?
(ii). Re- your aerial loop. Do you know its inductance? Or, do you know its tuning range when it is coupled with, say, a nominal 365 pF variable capacitor?

Just curious.

Al. / March 11, 2013 //

[Mark Hennessy]

Good work

The RT1 is an old set, using relatively basic transistors, and like all sets with that transistor line-up, the "fringe" performance was never fantastic. Sets using (working!) AF117s were always much more lively. When the R200 moved over to them, the change was quite dramatic. These later R200s were still a fair way behind a Mini-Herald though.

I've only had partial success supergluing ferrite rods back together. I think you might get away with it with a more recent set, but absolutely everything needs to be 100% spot on with these older beasts.

[Joe]

The trouble with the original rod was that attempts had been made at repair before I got it an the broken ends wouldn't touch-up closely enough for cyanacrylate to work. I'd hoped that with the splint being aluminium it would effect the magnetic properties but it obviously did.

I've no way of measuring the inductance of the loop but somebody with more mathematical ability than I may be able to work it out.

I connected my sig gen to my 'scope and set it for an output of 4mV at 800Kc/s. Without adjusting anything I then inserted the loop in series and the voltage dropped to 1.7mV.

   

- Joe