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Old 7th Feb 2018, 6:02 pm   #1
Philips210
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Default Advance Type 62 RF Signal Generator

Hi

I'm on the look out for a half reasonable RF signal generator such as a Marconi TF2015 or Philips PM5324 but in the meantime I came across this somewhat bashed around Advance type 62 signal generator. My question is, is this a fairly reliable RF generator for radio servicing? I'm thinking about reasonable amplitude stability across the frequency range. I have a Leader LSG-17 and have never been happy with it. It's amplitude stability is nothing short of awful.

I'm hoping that the Advance Type 62 will be a decent generator and will be worthwhile spending time to service it. Any thoughts on it's suitability?

Regards
Symon.
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Old 8th Feb 2018, 4:16 pm   #2
Vintage Engr
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Default Re: Advance Type 62 RF Signal Generator

I used one of these in the '60's, for day-to-day general servicing.
They are not a Lab instrument, but certainly good enough for servicing, rather than to use where exact frequency & stability are required.
They are reliable though.

I used to visit the Advance Factory in Hainault, to get ours calibrated. Sadly all gone now.

The Marconi would probably be a lot better in respect to amplitude across the bands, I have one of these, & it seems a good all-round generator.
I also have a Philips PM5324 that I've used since new & they are also fairly good, but again not a lab instrument. It's on my bench permanently, being used for most domestic radio jobs. The Philips is nice, because it also has a wob function.

I use both of them in conjunction with a frequency counter, so at least I know their accuracy at the time of use.

Hope that helps,

David.
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Old 8th Feb 2018, 4:53 pm   #3
Philips210
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Default Re: Advance Type 62 RF Signal Generator

Thanks for that David, that gives me more confidence in proceeding further with the Advance RF generator.
I am going to give it a good service and hope to put it to use. As you say when used in conjunction with a frequency counter then this is by far a more accurate way of knowing the o/p frequency than relying too much on what the dial indicates on the RF generator.

As an aside, I have acquired a Philips PM5334 TV RF sweep generator (wobbulator) but as yet haven't been able to look at it. Not having checked it's spec, I wonder if it has lower frequency ranges that would be suitable for radio work and operated just as a straight RF signal generator without the sweep facility in operation.

Regards
Symon.
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Old 15th Feb 2018, 4:06 pm   #4
Philips210
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Default Re: Advance Type 62 RF Signal Generator

Hi.

I've just been having an initial look at my Advance type 62 RF signal generator.
It appears to have been serviced by a previous owner and it at first seemed to have been carried out to a good standard.

The first thing I noticed was that a LED including two 220Ω resistors was used in place of the MES pilot lamp bulb. Then I found that a potentiometer was fitted to the front panel to alter the audio output level.
Most of the 0.04uF black Hunts capacitors have been replaced but by the wrong value caps. It seems the repairer must have had a stock of 0.022uF 630V polyester types which he's used for replacements.
He also replaced the live to earth and the neutral to earth caps with these as well. The correct value as depicted in the circuit diagram is 0.005uF or 5nF. I think 22nF that he used seems on the high side for a safety critical component. I intend to replace these with 4n7 250Vac class Y capacitors.
Another thing is the metal rectifier MR1 has been replaced with a silicon 1N5406, no problem with that except there's no series resistor so the HT voltage may well be on the high side. Any suggestions for a suitable value for this low demand application?
The mains wiring also needs attention and it will be worth fitting a new mains lead and making some safety improvements to insulating any exposed mains connections on the supply line chokes and the mains transformer.

The main circuitry is housed in an aluminium can, a bit like a huge but squat Denco coil cannister. The variable capacitor, range switch, valve and coil pack are built in the chassis mounted lid. The can then screws into the lid for complete RF screening. It looks like I need to remove this complete assembly from the chassis so that I can access the various components for testing and replacing any incorrect types.
The original 12AT7 valve has been replaced with a Mazda ECC81 so that should be alright but will check this on my Avo VCM.

The attenuator assembly is well made but contains a number of carbon composition resistors that have drifted high. This is also the case with several other resistors as well. The difficulty is deciding what to replace them with as this generator covers up to 220MHz. Using carbon film seems to be a reasonable choice though I wonder about self inductance exhibited by these due to the spiral trim cut. What would you suggest as the best option as I don't want to spoil the generator's performance? Originality of appearance is not important to me in this application so good performance must take precedence.
I have attached a few pics of my unit. A good copy of the manual can be found here https://www.kevinchant.com/advance.html which can be opened with Microsoft Word Viewer. Besides taking many photos of my unit, I have made a general sketch showing the locations of each component to assist when I start work on the repairs.

Regards
Symon.
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Last edited by Philips210; 15th Feb 2018 at 4:13 pm.
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Old 15th Feb 2018, 4:09 pm   #5
Philips210
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Default Re: Advance Type 62 RF Signal Generator

A couple more pics attached, this time showing the switched output attenuator assembly.

Regards
Symon.
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Old 15th Feb 2018, 8:33 pm   #6
karesz*
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Default Re: Advance Type 62 RF Signal Generator

Hi Symon,
you have to search for "Low inductance resistors" -i.e. from Beyschlag(yet is Vishay branded) _ I know, their have had an RF-serie in color "rose", I think up to 470 Ohm- they dont have a slotted spiral, just a line. Maybe Farnell/ RS etc has some other types too.
Otherwise I would take 1206 thik-film chip resistors it isn`t a problem to have in 1% and their are not expensive...
Rgds, Karl

Last edited by karesz*; 15th Feb 2018 at 8:39 pm.
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Old 16th Feb 2018, 9:28 am   #7
Philips210
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Default Re: Advance Type 62 RF Signal Generator

Thanks for your reply Karl, I'll check out the specs on low inductance resistors.

Regards
Symon.
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