TIP - Using a Philips PM5324 to sweep a low IF receiver - UK Vintage Radio Repair and Restoration Discussion Forum

ukcol · 15th Dec 2018, 5:52 pm

The Philips PM5324 has three sweep ranges all of which are outside the low IF range of early superheterodynes and outside the SW, MW and LW ranges of the receiver. I successfully used the generator to sweep a Murphy with a 119 kHz intermediate frequency using the following "trick".

It turns out the the 400 kHz to 500 kHz range falls within the image frequency range of the MW receiver. I disconnected the aerial input bandpass filter (which includes the image rejector) and resistance/capacitance coupled the generator directly to the control grid of the mixer valve.

The set was aligned using the spot frequency and damping component method in the manual and then a final tweak gave the correct bandpass curves using the above "trick".

The sweep ranges of the PM5324 are:

1] 75 ... 110 MHz,

2] 400 kHz ... 500 kHz

3] 10.3 ... 11.1 MHz

ukcol · 16th Dec 2018, 1:53 pm

I was thinking about the first post in this thread and realised it is sloppy and so I will do the test on my set again and give more accurate information in a furthur post, possibly tomorrow.

So ignore post No. 1 for now, sorry.

Kevin Hoyland · 16th Dec 2018, 3:17 pm

Hello Colin. I have the same Philips signal Generator but have never used it so I look forward to the next post. Please don't think the first post was poor. I enjoyed reading it .

Regards.
Kevin.

Herald1360 · 17th Dec 2018, 11:22 am

Made sense to me, but maybe I just automatically filled in the gaps once the principle was suggested. I did think "ah, but the frequency axis will be reversed" but for a symmetrical IF setup, that doesn't matter.

ukcol · 18th Dec 2018, 8:59 pm

OK lets see if I can make a better job of this this thread.

Proceed as follows.

Tune the receiver to about 112 kHz on the Long Wave, not MW as post No. 1.

This will put the image in the middle of the second sweep range of the PM5234 (400 - 500Khz).

It is essential to disconnect the first RF tuned circuit from the control grid of the mixer and R/C connect the generator to the mixer G1. This ensures that only the IF response influences the shape of the curve(s). If you leave the RF input circuit connected it is likely to distort the shape of the curves, particularly if an image rejector is included. A 0.01uf capacitor and a 1meg resistor will be suitable.

The exact numbers will be different for other low intermediate frequencies.

As Chris has already pointed out the frequency sweep will be in the opposite sense on the x axis but as the desired result is symmetry it is of no consequence. You will notice that curves 2 and 4 are not quite symmetrical but as the wider bandwidths are obtained with fixed value components there is not much that can be done to change them.

The method can be applied to any low IF receiver, the set I was working with has a 119kHz i.F. and switched selectivity. The results show were obtained after aligning the set using the spot frequency method described in the receiver's manual only.

15th Dec 2018, 5:52 pm	#1
ukcol Rest in Peace Join Date: May 2003 Location: Harlaxton, Lincolnshire, UK. Posts: 3,944	TIP - Using a Philips PM5324 to sweep a low IF receiver The Philips PM5324 has three sweep ranges all of which are outside the low IF range of early superheterodynes and outside the SW, MW and LW ranges of the receiver. I successfully used the generator to sweep a Murphy with a 119 kHz intermediate frequency using the following "trick". It turns out the the 400 kHz to 500 kHz range falls within the image frequency range of the MW receiver. I disconnected the aerial input bandpass filter (which includes the image rejector) and resistance/capacitance coupled the generator directly to the control grid of the mixer valve. The set was aligned using the spot frequency and damping component method in the manual and then a final tweak gave the correct bandpass curves using the above "trick". The sweep ranges of the PM5324 are: 1] 75 ... 110 MHz, 2] 400 kHz ... 500 kHz 3] 10.3 ... 11.1 MHz

16th Dec 2018, 1:53 pm	#2
ukcol Rest in Peace Join Date: May 2003 Location: Harlaxton, Lincolnshire, UK. Posts: 3,944	Re: TIP - Using a Philips PM5324 to sweep a low IF receiver I was thinking about the first post in this thread and realised it is sloppy and so I will do the test on my set again and give more accurate information in a furthur post, possibly tomorrow. So ignore post No. 1 for now, sorry.

16th Dec 2018, 3:17 pm	#3
Kevin Hoyland Heptode Join Date: Feb 2009 Location: Rotherham, South Yorkshire, UK. Posts: 559	Re: TIP - Using a Philips PM5324 to sweep a low IF receiver Hello Colin. I have the same Philips signal Generator but have never used it so I look forward to the next post. Please don't think the first post was poor. I enjoyed reading it . Regards. Kevin.

17th Dec 2018, 11:22 am	#4
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: TIP - Using a Philips PM5324 to sweep a low IF receiver Made sense to me, but maybe I just automatically filled in the gaps once the principle was suggested. I did think "ah, but the frequency axis will be reversed" but for a symmetrical IF setup, that doesn't matter. __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

18th Dec 2018, 8:59 pm	#5
ukcol Rest in Peace Join Date: May 2003 Location: Harlaxton, Lincolnshire, UK. Posts: 3,944	Re: TIP - Using a Philips PM5324 to sweep a low IF receiver OK lets see if I can make a better job of this this thread. Proceed as follows. Tune the receiver to about 112 kHz on the Long Wave, not MW as post No. 1. This will put the image in the middle of the second sweep range of the PM5234 (400 - 500Khz). It is essential to disconnect the first RF tuned circuit from the control grid of the mixer and R/C connect the generator to the mixer G1. This ensures that only the IF response influences the shape of the curve(s). If you leave the RF input circuit connected it is likely to distort the shape of the curves, particularly if an image rejector is included. A 0.01uf capacitor and a 1meg resistor will be suitable. The exact numbers will be different for other low intermediate frequencies. As Chris has already pointed out the frequency sweep will be in the opposite sense on the x axis but as the desired result is symmetry it is of no consequence. You will notice that curves 2 and 4 are not quite symmetrical but as the wider bandwidths are obtained with fixed value components there is not much that can be done to change them. The method can be applied to any low IF receiver, the set I was working with has a 119kHz i.F. and switched selectivity. The results show were obtained after aligning the set using the spot frequency method described in the receiver's manual only. Attached Thumbnails Last edited by ukcol; 18th Dec 2018 at 9:05 pm.