Lafayette HA-600 Receiver - UK Vintage Radio Repair and Restoration Discussion Forum

Biggles · 25th Nov 2009, 7:52 pm

Hi all, has anyone got any experience on faulting this general coverage receiver. It's a first generation solid state radio and is very deaf on all bands. I've traced the likely fault to be in the very first 455KHz IF stage, which consists of an IF transformer with an integral ceramic? filter. I'm reluctant to remove the IF can in case I cause more damage. I just thought that someone may have ideas on common faults with this model of receiver.

Cheers,
Biggles.

Skywave · 25th Nov 2009, 11:34 pm

I hate to state the blindingly obvious, but replacement of the filter is the quickest way! But no, I do realise that this probably isn't really an option for you - so your best bet is to eliminate the rest of the circuitry as being a possible culprit. But to do that, you do need the appropriate test gear. A sig. gen to inject a signal at the IF after the filter and also to inject sigs. at the aerial socket - and a 'scope to examine the resultant sigs. If all looks OK, then replacement of the suspect filter has to be the next step.

Mind you, where you'd get one from I know not.

Al. / Skywave.

MichaelR · 26th Nov 2009, 10:35 am

Biggles,

Just a comment but this receiver usually has a plug in the remote socket and it must be there for the receiver to work properly. Also it should have 2 links wired inside the plug.

Mike

Biggles · 3rd Dec 2009, 10:19 pm

Well I took the plunge and removed the offending filter/IF can combination, and sure enough there is an o/c on the IF transformer secondary which feeds into the two stage crystal (or maybe ceramic) filter. Its impossible to find this fault without removing the IF can, as the first filter has a top coupling capacitor linking it to the second stage, and also straight into a parallel winding on a second IF transformer, effectively masking any continuity tests anyway. It looks like a previous owner has been twiddling and tightened the IF slug down too far and mashed the windings. The filter has survived intact so I may be able to graft it onto another 455KHz IF coil from the spares box and hope the IF filter shape hasn't been modified too much after the surgery. I suppose a radio with a slightly wider IF response is better than no receiver at all! I'll hopefully get around to the delicate operation this weekend...

Biggles.

25th Nov 2009, 7:52 pm	#1
Biggles Rest in Peace Join Date: Feb 2004 Location: Hexham, Northumberland, UK. Posts: 2,234	Lafayette HA-600 Receiver Hi all, has anyone got any experience on faulting this general coverage receiver. It's a first generation solid state radio and is very deaf on all bands. I've traced the likely fault to be in the very first 455KHz IF stage, which consists of an IF transformer with an integral ceramic? filter. I'm reluctant to remove the IF can in case I cause more damage. I just thought that someone may have ideas on common faults with this model of receiver. Cheers, Biggles.

25th Nov 2009, 11:34 pm	#2
Skywave Rest in Peace Join Date: Jun 2006 Location: Chard, South Somerset, UK. Posts: 7,457	Re: Lafayette HA-600 Receiver I hate to state the blindingly obvious, but replacement of the filter is the quickest way! But no, I do realise that this probably isn't really an option for you - so your best bet is to eliminate the rest of the circuitry as being a possible culprit. But to do that, you do need the appropriate test gear. A sig. gen to inject a signal at the IF after the filter and also to inject sigs. at the aerial socket - and a 'scope to examine the resultant sigs. If all looks OK, then replacement of the suspect filter has to be the next step. Mind you, where you'd get one from I know not. Al. / Skywave.

26th Nov 2009, 10:35 am	#3
MichaelR Retired Dormant Member Join Date: Mar 2006 Location: Sheffield, South Yorkshire, UK. Posts: 1,587	Re: Lafayette HA-600 Receiver Biggles, Just a comment but this receiver usually has a plug in the remote socket and it must be there for the receiver to work properly. Also it should have 2 links wired inside the plug. Mike

3rd Dec 2009, 10:19 pm	#4
Biggles Rest in Peace Join Date: Feb 2004 Location: Hexham, Northumberland, UK. Posts: 2,234	Re: Lafayette HA-600 Receiver Well I took the plunge and removed the offending filter/IF can combination, and sure enough there is an o/c on the IF transformer secondary which feeds into the two stage crystal (or maybe ceramic) filter. Its impossible to find this fault without removing the IF can, as the first filter has a top coupling capacitor linking it to the second stage, and also straight into a parallel winding on a second IF transformer, effectively masking any continuity tests anyway. It looks like a previous owner has been twiddling and tightened the IF slug down too far and mashed the windings. The filter has survived intact so I may be able to graft it onto another 455KHz IF coil from the spares box and hope the IF filter shape hasn't been modified too much after the surgery. I suppose a radio with a slightly wider IF response is better than no receiver at all! I'll hopefully get around to the delicate operation this weekend... Biggles.