Wavetek 2407 Signal generator - UK Vintage Radio Repair and Restoration Discussion Forum

allan · 5th Jul 2020, 12:02 pm

A few weeks back I tackled the repair of a rather battered HP8640B signal generator, a replacement for my sick Wavetek 2407.
The Wavetek has been giving trouble over the last couple of years with faults traced back to semiconductors rather than mechanical troubles with the non-microprocessor HP example.
The Wavetek may be close to end of life, but I like a challenge and it may be of some interest to others to hear of the parts that are giving trouble.
In roughly the order I've found these... MRF271, MRF839F, a 10uF tantalum (connected back-to-front), MSA0204, a second MRF271 and an MJE253.
No digital i/c problems thankfully. There was a bad 74LS96 in the HP8640B.

It was nice to be able to rely on my repaired HP8640B for testing the Wavetek and I guess it was useful to have my DSA815 to track down the latest Wavetek problems of low RF output coupled with harmonics.
http://www.radiomuseum.co.uk/wavetek.html
Allan G3PIY

Julesomega · 5th Jul 2020, 3:17 pm

Very maintainable, I'd have thought, as long as you have a manual. Wavetek handbooks are thin on the ground

allan · 6th Jul 2020, 9:50 am

I actually have the (vital) 2407 Manual Jules. Having sorted out the RF amplifiers I did a quick check to see how the output looked across the range which is 10KHz to 550MHz. Not bad except where I tried to adjust the thing to compensate for a bad amplifier. The +13dBm setting now reads +16dBm across the range for example.
The manual has a chapter on instrument calibration and starts with the heading "AUTOCAL CALIBRATION" so I thought.. great, I just press a button and everything gets sorted out. No such luck, reading the blurb I realise that the "AUTO" bit isn't exactly automatic as I reckon it will need between 200 and 300 presses of front panel buttons. Each of 31 preset frequencies requires the output to be adjusted to 0dBm to achieve flatness across the frequency range. Having done that the linearity also needs to be adjusted.
Autocal requires 6 pages of technospeak.. clearly not just "Press the Autocal button"
Allan G3PIY

5th Jul 2020, 12:02 pm	#1
allan Pentode Join Date: Oct 2005 Location: South coast near Ringwood/Christchurch, Dorset, UK. Posts: 230	Wavetek 2407 Signal generator A few weeks back I tackled the repair of a rather battered HP8640B signal generator, a replacement for my sick Wavetek 2407. The Wavetek has been giving trouble over the last couple of years with faults traced back to semiconductors rather than mechanical troubles with the non-microprocessor HP example. The Wavetek may be close to end of life, but I like a challenge and it may be of some interest to others to hear of the parts that are giving trouble. In roughly the order I've found these... MRF271, MRF839F, a 10uF tantalum (connected back-to-front), MSA0204, a second MRF271 and an MJE253. No digital i/c problems thankfully. There was a bad 74LS96 in the HP8640B. It was nice to be able to rely on my repaired HP8640B for testing the Wavetek and I guess it was useful to have my DSA815 to track down the latest Wavetek problems of low RF output coupled with harmonics. http://www.radiomuseum.co.uk/wavetek.html Allan G3PIY Attached Thumbnails

5th Jul 2020, 3:17 pm	#2
Julesomega Nonode Join Date: Dec 2012 Location: Stockport, Greater Manchester, UK. Posts: 2,102	Re: Wavetek 2407 Signal generator Very maintainable, I'd have thought, as long as you have a manual. Wavetek handbooks are thin on the ground __________________ - Julian It's good here

6th Jul 2020, 9:50 am	#3
allan Pentode Join Date: Oct 2005 Location: South coast near Ringwood/Christchurch, Dorset, UK. Posts: 230	Re: Wavetek 2407 Signal generator I actually have the (vital) 2407 Manual Jules. Having sorted out the RF amplifiers I did a quick check to see how the output looked across the range which is 10KHz to 550MHz. Not bad except where I tried to adjust the thing to compensate for a bad amplifier. The +13dBm setting now reads +16dBm across the range for example. The manual has a chapter on instrument calibration and starts with the heading "AUTOCAL CALIBRATION" so I thought.. great, I just press a button and everything gets sorted out. No such luck, reading the blurb I realise that the "AUTO" bit isn't exactly automatic as I reckon it will need between 200 and 300 presses of front panel buttons. Each of 31 preset frequencies requires the output to be adjusted to 0dBm to achieve flatness across the frequency range. Having done that the linearity also needs to be adjusted. Autocal requires 6 pages of technospeak.. clearly not just "Press the Autocal button" Allan G3PIY