Racal-dana 9301a (9300) - UK Vintage Radio Repair and Restoration Discussion Forum

klaustrom · 27th Sep 2022, 4:20 pm

Dear all,
some investigation via the vintage-radio.net forum and friendly RSGB helped to find your contact.
I own a RMS voltmeter 9301A in very fine condition. However it is faulty. I could narrow the reason down to the sample&hold circuitry but have to stop here due to a lack of test equipment.
I have the manual and service manual at hand.
Could you advise me how to proceed? I even would ship the instrument to the UK/ British isles if appropriate, to someone willing to do the repair.
Looking forward to have this extremely solid built meter working again I await your answer.
Klaus DL7TW

PETERg0rsq · 27th Sep 2022, 11:08 pm

Klaus

I have repaired several of these meters (the 9300 is very different to the 9301), and some tests do need good test equipment, especially when checking probe nulling, as signals down to 5mV or less need observing.

Be very careful when working with the probe as the SRD is unobtainable, but it is usually the four rf diodes that fail when overloaded (max input is about 10v p-p before they will blow)

To calibrate the instrument it is essential to have some accurate attenuaters.

What test equipment do you have access to?

When I start fault finding I usually start at the beginning of the maintenance section, and work through the setting/adjustments until I cant get the desired result, and fault find from there.

What part of the maintenance section can you work to until you cant get he required results?

The 9301 is a great instrument when working, and a valuable addition to any RF test equipment.

27th Sep 2022, 4:20 pm	#1
klaustrom Diode Join Date: Sep 2022 Location: Berlin, Germany. Posts: 1	Racal-dana 9301a (9300) Dear all, some investigation via the vintage-radio.net forum and friendly RSGB helped to find your contact. I own a RMS voltmeter 9301A in very fine condition. However it is faulty. I could narrow the reason down to the sample&hold circuitry but have to stop here due to a lack of test equipment. I have the manual and service manual at hand. Could you advise me how to proceed? I even would ship the instrument to the UK/ British isles if appropriate, to someone willing to do the repair. Looking forward to have this extremely solid built meter working again I await your answer. Klaus DL7TW

27th Sep 2022, 11:08 pm	#2
PETERg0rsq Heptode Join Date: Jun 2009 Location: St Helens, Lancashire, UK. Posts: 641	Re: Racal-dana 9301a (9300) Klaus I have repaired several of these meters (the 9300 is very different to the 9301), and some tests do need good test equipment, especially when checking probe nulling, as signals down to 5mV or less need observing. Be very careful when working with the probe as the SRD is unobtainable, but it is usually the four rf diodes that fail when overloaded (max input is about 10v p-p before they will blow) To calibrate the instrument it is essential to have some accurate attenuaters. What test equipment do you have access to? When I start fault finding I usually start at the beginning of the maintenance section, and work through the setting/adjustments until I cant get the desired result, and fault find from there. What part of the maintenance section can you work to until you cant get he required results? The 9301 is a great instrument when working, and a valuable addition to any RF test equipment. __________________ SPECIALIST.....Knows everything about nothing EXPERT..........Knows nothing about everything