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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment.

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Old 18th Mar 2020, 4:58 pm   #41
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Default Re: Lafayette HE-40

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Yes. It would appear that the heater is short-circuit. Not something I've come across before, but that's what the test result says.

As an additional check you could measure the volts across the other heaters and lamps.
Yes, that is very strange. It was working before the R5 burnt out.
After that, it was not lighting up.

The only pin has voltage out is the pin 5, about 4V AC.

Do you mean to check the other valves heaters and the tuning dial lamps voltages?
Did you measure with one probe on pin 3 and the other on pin 4? You could also check the voltage between each heater pin and chassis.
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Old 18th Mar 2020, 5:11 pm   #42
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Default Re: Lafayette HE-40

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Did you measure with one probe on pin 3 and the other on pin 4? You could also check the voltage between each heater pin and chassis.
Yes, I did. No voltages coming out from this valve.
But without the valve, the set doesn't power on.

The only pin with the voltage is pin5, and reads 4V.
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Old 18th Mar 2020, 5:18 pm   #43
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Default Re: Lafayette HE-40

The valve heaters are wired in series, so one out all out.
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Old 18th Mar 2020, 7:09 pm   #44
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Default Re: Lafayette HE-40

Yes, this set started working the now. The valve pins were having poor connection to the valve socket. Stretched them out to force firm connection seemed to work.

MW reception is very good, but SW reception has hum. BFO is poor not resolving ssb or cw very well. But AM reception seem ok. Just the hum is still problem.

Thank you so much everyone who gave info and advice.

https://youtu.be/aIu9dKhUjAw
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Old 18th Mar 2020, 7:37 pm   #45
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Default Re: Lafayette HE-40

BFO seems settling ok too. This was 30m band.
https://youtu.be/nFSC9cQpSz0
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Old 18th Mar 2020, 8:02 pm   #46
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Default Re: Lafayette HE-40

I have a Star DX Mates SR-120 that is a very similar receiver. I enjoy listening to the radio amateurs on 80m's when the conditions are good. Mine I don't think has been overhauled, it belonged to a radio amateur before me that sadly passed away, and his son was selling off his radio gear. So in a way it's quite fitting to listen to radio amateurs on. I find mine to be a bit quite on band 4 11-30Mhz.
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Old 18th Mar 2020, 8:58 pm   #47
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Default Re: Lafayette HE-40

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Yes, this set started working the now. The valve pins were having poor connection to the valve socket. Stretched them out to force firm connection seemed to work.
That no sense to me. If there was a high resistance between the valve's pins and the contacts in the valve holder then the other three valves wouldn't light up, but apparently they did.

Also with a high resistance contact you'd expect to see something like 120 VAC across pins 3 and 4 of the valve holder, but you measured zero volts.

Is it possible that with the valve plugged in contacts 3 and 4 of the valve holder were shorting together? Perhaps via their tags?
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Old 18th Mar 2020, 9:04 pm   #48
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Default Re: Lafayette HE-40

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That no sense to me. If there was a high resistance between the valve's pins and the contacts in the valve holder then the other three valves wouldn't light up, but apparently they did.

Also with a high resistance contact you'd expect to see something like 120 VAC across pins 3 and 4 of the valve holder, but you measured zero volts.
You're not alone.

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Old 18th Mar 2020, 11:57 pm   #49
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Default Re: Lafayette HE-40

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Yes, this set started working the now. The valve pins were having poor connection to the valve socket. Stretched them out to force firm connection seemed to work.
That no sense to me. If there was a high resistance between the valve's pins and the contacts in the valve holder then the other three valves wouldn't light up, but apparently they did.

Also with a high resistance contact you'd expect to see something like 120 VAC across pins 3 and 4 of the valve holder, but you measured zero volts.

Is it possible that with the valve plugged in contacts 3 and 4 of the valve holder were shorting together? Perhaps via their tags?
I am also not understanding it. All I have done was, after soldering on 47k and 220r and 100r in series for the burnt 5k ohm resistor, then taking out the 12AV6 a few times, and keep powering on and off. It still wasn't doing anything.

I was desperate to find a substitue valve for the 12AV6 then. I was looking into some of the old valve radios if any one of them had 12AV6, but none seemed to.
I really wanted to try out a new 12AV6. I was convinced the 12AV6 was bad. I almost bought a 12AV7 from eBay as well. I am glad I didn't.

When I pushed the pins further out the way, and out the valve in, and it made noise, and started receiving.

It was only receiving on MW. SW was full of hums and there were no transmitted signals.

It slowly started getting better, and later it was actually receiving real good.
It is really sensitive, and has superb audio on MW and SW AM.
SW SSB and CW is not bad either when it is warmed up and BFO is set right, it is very nice to listen to.

All I can say is, thank you. I learnt a lot, and the radio is now working OK.
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Old 19th Mar 2020, 4:54 am   #50
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Default Re: Lafayette HE-40

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I find mine to be a bit quite on band 4 11-30Mhz.
We're at the low point of the sunspot cycle, and there isn't much going on on those bands compared to what happens on sunspot peak times. You might find some activity on 14MHz for a couple of hours on a good day when the band may open.

But these were made as affordable sets selling to shortwave listeners who only had pocket money as income. In general, their performance is pretty low. They sold on price and styling. As a kid I drooled over the sketchy drawings in the adverts in PW, but I saved up a bit longer and bought an AR88. The sensitivity of these sets was known to be rather poor on the top frequency band. Quite a number of expensive military sets got more than a little deaf towards the top of the HF range as well. The AR88 was a bit special, the maker had deployed some new technology, polystyrene coil formers for the top range. This was right at the very dawn of plastics. But we're comparing a military, cost-no-object radio with something targeted from new at hobbyists... but on the market back in the day, that was the choice. The second-hand ex-military set went for double the price of the Lafayette, but you got the performance difference appropriate to the new prices of both.

If you want the Lafayette set for a bit of fun, for part of a collection, or just to get one going to see what they were like, then why not.

If you want a useable short wave radio to listen on the bands, then you'll soon find its limitations... not terribly sensitive, not terribly selective, and a bit drifty... but they still work!

Back in the day, I thought they looked great, but when the chips were down, I spent my collected Christmas and birthday money and my hard-earned cash on the alternative. Still got that AR88.

From a collection point of view, CR100, HRO and AR88 receivers are pretty common and routine, a restored sixties SWL set has rarity on its side.

David
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Old 19th Mar 2020, 11:05 am   #51
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Default Re: Lafayette HE-40

Yes, this Lafayettes would be no match for AR-88 or Racals or Eddystones in performance and quality of construction.
But they are light weight, smaller in size and simple design. Easier to service and modify or repair than the bigger and heavier radios.
With good antenna and band condition, they can be tremendous fun to listen about the bands too.

Last night, I was listening to 5-7Mhz with the HE-40, and there were hundreds of stations coming up. Every tiny movement of the tuning dial, there was stations appearing with good signal and audio. It was great fun to listen to these stations.
Later, I went to 3-4Mhz, and 80m ssb was good, and there were also quite a few very strong commercial SW stations. I used to think SW broadcast stations had been all gone, but I was wrong. There are still plenty there. Maybe they are coming back. I don't know, but one thing clear was the band was very busy.

I found out why it was reading 0V on the 12AV6 heaters yesterday. I was using the Volt meter from my Insulation Resistance Meter rather than normal DMM.
This meter can read Voltages from 30V - 600V AC, hence it was not registering 12V off the heaters.
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Old 19th Mar 2020, 11:22 am   #52
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Default Re: Lafayette HE-40

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I found out why it was reading 0V on the 12AV6 heaters yesterday. I was using the Volt meter from my Insulation Resistance Meter rather than normal DMM.

This meter can read Voltages from 30V - 600V AC, hence it was not registering 12V off the heaters.
Unless the voltmeter had a very low internal resistance you should have read around 120VAC with a high resistance connection to the heater pins.
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Old 19th Mar 2020, 12:03 pm   #53
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Default Re: Lafayette HE-40

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Unless the voltmeter had a very low internal resistance you should have read around 120VAC with a high resistance connection to the heater pins.
It was reading 0V on the heaters. Not sure, if the Meter is faulty. I only got it a few days ago from Amazon delivered from China. Will check the meter out.
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Old 19th Mar 2020, 2:59 pm   #54
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Default Re: Lafayette HE-40

There's a lot to be said for having a good, dependable multimeter and saving specialised items for specialised tests. If your test gear doesn't do what you think it should be doing, it can lead you on a right mystery tour and destroy whatever confidence you have in what you're doing.

If a test with a meter says "there is no voltage here" and the reading is misleading (or you selected DC when there was AC or vice-versa) then you could get a bad shock if you trust the meter.

Without going over the top, there is a sensible level of distrust to treat things with. If I'm going to trust my life to something, I like an independent double-check.

David
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Old 19th Mar 2020, 3:46 pm   #55
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Arrow Re: Lafayette HE-40

Following on from David's post above, it's always a good idea to collect appropriate test gear so that you always have another instrument available to measure any electrical quantity. With a piece of test gear that doesn't tell you the 'truth' and leading you to arrive at erroneous conclusions, you're actually better off using guess work.
Finally, it's always worthwhile checking the calibration of all your test equipment annually.

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Old 19th Mar 2020, 4:15 pm   #56
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Default Re: Lafayette HE-40

Be a little cautious about trusting calibration certificates, or just your own checks.

A cal cert is a proof that the thing was working OK when tested, and you can presume that it must therefore have been OK up to that point. So if someone dropped it the day after certification, everything tested could be dodgy from then on until the problem gets spotted at next year's calibration fest.

I'm involved with making aircraft electronics including instrument landing systems, anti collision systems etc. This stuff has to be as right as it can be made. Occasionally a piece of lab equipment is found out of one spec or another. As well as readjusting the instrument, we have to review to consequences. Could it cause any product to be out of spec? How far back do we have to go.

It's quite difficult to get people to understand that calibration is essentially backwards looking, not forwards.

Test gear at home is rarely formally calibrated, but it's useful to have something as a back-up to double check against.

For professional or amateur work, the most valuable thing is a good nose for smelling when something isn't right. If you don't smell a rat and do a double check, you can be off on a right merry game.

David
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Old 20th Mar 2020, 3:19 pm   #57
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Default Re: Lafayette HE-40

The meter I used is a Vici and it was the cheapest one for the kind from Amazon.
The meter seems OK, but supplied leads are poor quality. It gives connection problems at times.

I have now discarded the leads, and ordered a new set of test leads kit for the meter.
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