Philips PM5320 RF generator

This is a very useful RF generator from Philips. It has AM and FM modulation (frequency sweeping). It covers all broadcast bands and the usual IF ranges for AM and FM.

The frequency ranges are:

• 150-480kHz (LW)
• 400-500kHz (IF for AM)
• 0.48-1.5MHz (MW)
• 1.5-4.8MHz (SW)
• 4.8-15MHz (SW)
• 10-11.5MHz (IF for FM)
• 15-50MHz (SW)
• 88-108MHz (FM band)

The valve line-up is:

• ECC85 as RF oscillator,
• E80F as RF output amplifier,
• ECF82 as AF oscillator and driver for FM modulation,
• EZ80 as rectifier,
• PCL82 as power supply voltage regulator,
• 85A2 as voltage reference for the power supply.

This RF generator was offered in 2018 on the Dutch forum on old radios. The seller didn't know if it was functioning, but it was looking like in good condition. After I collected it, I didn't want to switch it on just like that but to test it properly before I were to use it. But I wasn't in a hurry, I had a good working GM2883 generator and I wasn't repairing many radios at the time. So it sat on a shelf for a number of years.

In October 2024 I decided to test the generator and make it operational. I prepared for the worst, but everything turned out fine. First I took the covers from the metal case. The inside was looking good, just al little bit of dust. The inside of the oscillator box looked pristine. I started with the power electrolytics. These measured good and had practically no leakage current after reforming. I turned the generator on and checked the power supply. The voltage was OK and needed just a little correction.

Then I checked the output signal. This was looking good. AM modulation worked fine. I was happy to have this instrument ready to use on my workbench.

Its first use came in Februari and March 2025 to align my KY585 radio.

The frequency sweep function was incredibly useful to onderstand the problems in that radio and to align the ratio detector. I was slightly puzzled by the loopy, Lissajous-like scope image. The output of the generator was out of phase with the horizontal signal to the scope. The solution was simple: The PM5320 has a phase control at the back. By adjusting the phase control, the loop almost disappeared.

Just after the tests of this PM 5320 I also acquired a PM5321, which is the slightly improved successor to the PM5320. In april 2025 I tested it. I decided to keep the PM5321, and sold this excellently working PM5320 to a fellow hobbyist.