Advance E2 - UK Vintage Radio Repair and Restoration Discussion Forum

eaglework · 30th Aug 2017, 5:13 pm

I have an Advance E2 that I picked up from a forum member a few months ago. After replacing the HT smoothing caps and a general clean up it works quite well apart from on the highest frequency range where it refuses to oscillate at anything less than approx. 38-39MHz. On a scope the output falls as you reduce the frequency below about 45MHz and it stops oscillating at 39MHz.
All the other ranges are fine and pretty much on spec in terms of accuracy.

I haven't tried a replaced valve (ECC91) yet, as I don't have one, but I was thinking a faulty valve would be more likely to stop oscillating at the HF rather than LF end of the band.
Any thoughts?

Jon

Sideband · 30th Aug 2017, 8:16 pm

Yes if the valve was low than the HF end would suffer first. Certainly worth trying a new one as the rest of the generator is pretty bulletproof.

WME_bill · 30th Aug 2017, 10:22 pm

I have an E2 which behaves in a similar way. Below about 40Mhz on the highest frequency range A, the output drops significantly and finally oscillation ceases below 30Mhz. This part of the range the scale is not calibrated, suggesting that you should change to the top of the next lower range 10 to 32 Mhz.
When I got the generator, it hardly oscillated on the highest range at all, but after cleaning the switch and the variable capacitor contacts and then changing the valve, it was fine.
The output is virtually constant on all the other ranges except to drop off a little (10%) at the extreme low frequency end of each range.
Your proposed change of the 6J6 / ECC91 valve sounds right. Make sure the valve pins and holder socket are cleaned. The gm on both sections of my original valve were a bit low. That of the replacement valve is up near the usual data tables values.
wme_bill m0wpn

eaglework · 31st Aug 2017, 7:37 am

Thanks and yes it sounds like a replacement ECC91 is the next step.
The switch, although looking a bit grubby, seems to be fine and no evidence of funnies on the other ranges so I wasn't suspicious of the variable cap but I will check just in case.
The case on mine has some surface rust especially on the back - any ideas on the paint colour - its BS or RAL number?

30th Aug 2017, 5:13 pm	#1
eaglework Pentode Join Date: Jun 2017 Location: Alton, Hampshire, UK. Posts: 159	Advance E2 I have an Advance E2 that I picked up from a forum member a few months ago. After replacing the HT smoothing caps and a general clean up it works quite well apart from on the highest frequency range where it refuses to oscillate at anything less than approx. 38-39MHz. On a scope the output falls as you reduce the frequency below about 45MHz and it stops oscillating at 39MHz. All the other ranges are fine and pretty much on spec in terms of accuracy. I haven't tried a replaced valve (ECC91) yet, as I don't have one, but I was thinking a faulty valve would be more likely to stop oscillating at the HF rather than LF end of the band. Any thoughts? Jon

30th Aug 2017, 8:16 pm	#2
Sideband Dekatron Join Date: Oct 2003 Location: Croydon, Surrey, UK. Posts: 7,572	Re: Advance E2 Yes if the valve was low than the HF end would suffer first. Certainly worth trying a new one as the rest of the generator is pretty bulletproof. __________________ There are lots of brilliant keyboard players and then there is Rick Wakeman.....

30th Aug 2017, 10:22 pm	#3
WME_bill Octode Join Date: Oct 2007 Location: Exeter, Devon, UK. Posts: 1,554	Re: Advance E2 I have an E2 which behaves in a similar way. Below about 40Mhz on the highest frequency range A, the output drops significantly and finally oscillation ceases below 30Mhz. This part of the range the scale is not calibrated, suggesting that you should change to the top of the next lower range 10 to 32 Mhz. When I got the generator, it hardly oscillated on the highest range at all, but after cleaning the switch and the variable capacitor contacts and then changing the valve, it was fine. The output is virtually constant on all the other ranges except to drop off a little (10%) at the extreme low frequency end of each range. Your proposed change of the 6J6 / ECC91 valve sounds right. Make sure the valve pins and holder socket are cleaned. The gm on both sections of my original valve were a bit low. That of the replacement valve is up near the usual data tables values. wme_bill m0wpn

31st Aug 2017, 7:37 am	#4
eaglework Pentode Join Date: Jun 2017 Location: Alton, Hampshire, UK. Posts: 159	Re: Advance E2 Thanks and yes it sounds like a replacement ECC91 is the next step. The switch, although looking a bit grubby, seems to be fine and no evidence of funnies on the other ranges so I wasn't suspicious of the variable cap but I will check just in case. The case on mine has some surface rust especially on the back - any ideas on the paint colour - its BS or RAL number?