50W ss Arrowslim choke
First cleanup and test of 50W Arrowslim switchstart fitting from the May 2019 meet. It struggles to start with weak preheat, and the tube flickers a bit while running as if the starter is partially glowing. I can understand why they moved to SRS.

50W ss Arrowslim choke

First cleanup and test of 50W Arrowslim switchstart fitting from the May 2019 meet. It struggles to start with weak preheat, and the tube flickers a bit while running as if the starter is partially glowing. I can understand why they moved to SRS.

11_Humming_coolly_like_a_good__un.JPG 50W_ss_Arrowslim.JPG 50W_ss_Arrowslim_choke.JPG 50W_ss_Arrowslim_control_gear.JPG 50W_ss_Arrowslim_series_capacitor.JPG
File information
Filename:50W_ss_Arrowslim_choke.JPG
Album name:BC5-80 / Fittings
Manufacturer:Thorn
Type/Model:Arrowslim
Wattage:50W
Date manufactured:16/71
Filesize:89 KiB
Date added:06 May, 2020
Dimensions:1024 x 576 pixels
Displayed:23 times
URL:http://80.229.24.59:9232/gallery/displayimage.php?pid=13776
Favourites:Add to Favourites

Comment 1 to 9 of 9
Page: 1

Slyspark   [07 May, 2020 at 12:01 AM]
If the fitting struggles to start the tube, might be worth replacing the series capacitor.....
Oliver   [07 May, 2020 at 12:40 AM]
I would have thought it would be the starter.
Slyspark   [07 May, 2020 at 01:25 AM]
On a fitting with a SERIES cap, a weak cap will make striking the tube virtually impossible. A good example being an 8' 125w circuit with series 7.2mfd cap - older fittings often struggle to start the tube, stick a new cap in a d bang, good as new!
BC5-80   [07 May, 2020 at 11:29 AM]
I'm hoping the capacitor will be OK. The fitting doesn't look as though it's had much use. Anyway, it's impossible to come by 3.85uF +/-5% 440V capacitors these days. Any replacement would probably have to be a hand-picked series combination of two higher values. Once running it's perfectly fine, not dim or anything. I did have a 6' fitting with weak capacitor. That started no problem but it was noticeably dim due to the low capacitance. I have heard that 50W switchstart had low preheat current and starting issues, which is why they standardised on SRS.
Slyspark   [07 May, 2020 at 10:35 PM]
Hmm, no, you might get lucky with a 4mfd cap, which I';d guess would be close enough.....
BC5-80   [08 May, 2020 at 01:08 AM]
It's been running really well on a variety of tubes. It's just the starts that are a bit protracted at times.
Slyspark   [08 May, 2020 at 02:12 AM]
Ah well, could be worse then I guess!
BC5-80   [08 May, 2020 at 10:49 AM]
It seems to be starting pretty well now. The last tube I've got on test (Atlas Pink) starts pretty quickly. I wonder if the NOS starter has settled down? The lamps are flickering much less during running, so perhaps any rogue glow discharge in the starter has subsided?
Slyspark   [08 May, 2020 at 01:36 PM]
You have a 50w tube IN PINK!!! Never would have assumed such a thing existed Surprised

Comment 1 to 9 of 9
Page: 1

Add your comment
Anonymous comments are not allowed here. Log in to post your comment