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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment. |
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20th Jun 2020, 1:33 pm | #1 |
Tetrode
Join Date: Feb 2012
Location: Bishop Auckland, County Durham, UK.
Posts: 92
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Labgear Topbander
I've acquired a Labgear topbander transmitter which needs restoration. I know there were 2 variants of this, I suspect I have the latter.
The original MK1, whose circuit is readily available on the net shows a modulator valve line up of EF80, 12AU7 and 12BH7. The version I have, has a modulator valve line up of EF80 (mic amp) followed by an ECL82 (triode pentode) and another valve (definitely not a double triode or an ECL82) which has lost its markings. Some of the wiring around the mod section has been disrupted. Does anyone have the schematic for what I presume is the MK2 version of this transmitter? Cheers Andy G4OJY |
20th Jun 2020, 5:27 pm | #2 |
Tetrode
Join Date: Feb 2012
Location: Bishop Auckland, County Durham, UK.
Posts: 92
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Re: Labgear Topbander
I've made a little progress. The topbander manual djvu file on boat anchor manual archive mentions the modulator valve line up as EF80, ECL82 and EL84, so I guess this is what I have. There is no schematic with this manual, but the manual for the labgear LG160 does have a crude schematic with an EL84 modulator.
At least I can now try and retrace the schematic knowing what the valve line up in the mod is. |
20th Jun 2020, 11:44 pm | #3 |
Octode
Join Date: Feb 2009
Location: Bletchley, Buckinghamshire, UK.
Posts: 1,219
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Re: Labgear Topbander
I have the circuit diagram for that version (stated as for use with transmitter serial numbers prefixed "S" only).
I need to scan it in sections and stitch them together. Also the relevant manual, a bit yellow with age but will probably clean up OK. Watch this space... |
21st Jun 2020, 8:30 am | #4 |
Tetrode
Join Date: Feb 2012
Location: Bishop Auckland, County Durham, UK.
Posts: 92
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Re: Labgear Topbander
Thanks Dave that will be really useful.
Andy |
21st Jun 2020, 2:02 pm | #5 |
Octode
Join Date: Feb 2009
Location: Bletchley, Buckinghamshire, UK.
Posts: 1,219
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Re: Labgear Topbander
Here is the circuit. It will be compressed by the forum software, so if it's not readable I will try again.
edit: Not readable on the forum, but I can send the file to you if you PM me an email address (don't post it here). Last edited by m0cemdave; 21st Jun 2020 at 2:28 pm. |
21st Jun 2020, 2:28 pm | #6 |
Moderator
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,288
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Re: Labgear Topbander
If you can convert it to a .pdf file the forum accepts these up to 4M.
__________________
Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
22nd Jun 2020, 11:58 am | #7 |
Pentode
Join Date: Jun 2013
Location: Worthing, West Sussex, UK.
Posts: 223
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Re: Labgear Topbander
Dave
Can I ask a favour as well, can you send me a copy as well, mine is working well but it would be nice to have for reference. 73 Andy G3UEQ QTHR QRZ.com |
22nd Jun 2020, 10:14 pm | #8 |
Octode
Join Date: Feb 2009
Location: Bletchley, Buckinghamshire, UK.
Posts: 1,219
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Re: Labgear Topbander
The Topbander Mk2 manual:
These pages are all readable on here, but if anyone wants a higher resolution copy for printing etc please send me a PM with an email address. (see next message for the last two pages) Last edited by m0cemdave; 22nd Jun 2020 at 10:23 pm. |
22nd Jun 2020, 10:15 pm | #9 |
Octode
Join Date: Feb 2009
Location: Bletchley, Buckinghamshire, UK.
Posts: 1,219
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Re: Labgear Topbander
last pages:
Last edited by m0cemdave; 22nd Jun 2020 at 10:20 pm. |
22nd Jun 2020, 10:16 pm | #10 |
Octode
Join Date: Feb 2009
Location: Bletchley, Buckinghamshire, UK.
Posts: 1,219
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Re: Labgear Topbander
Andy (ribbon mics), you have a PM.
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23rd Jun 2020, 5:39 am | #11 |
Heptode
Join Date: Jun 2012
Location: Southeast Norfolk, UK.
Posts: 773
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Re: Labgear Topbander
Hi All,
I put the MK1 manual on BAMA many moons ago, see here:- http://bama.edebris.com/manuals/labgear/topbander Unfortunately, I didn't own a MK2 and so have never chased up the manual for that mark. If a copy is located could the finder please add it to the BAMA directory and let the group know? 73 Roger/G3VKM |
28th Jun 2020, 4:41 pm | #12 |
Tetrode
Join Date: Feb 2012
Location: Bishop Auckland, County Durham, UK.
Posts: 92
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Re: Labgear Topbander
I've finally got the tx up and running. Can anyone with the MK2 version comment on how much output power they are getting. Into a 50 ohm load I get just under 5 watts. PA anode current is about 35mA dipped in the CW position.
I cannot get more than 1mA of grid current even with the drive pot on max, though the manual says I should be able to get at least 2.5mA I have peaked L3 for max grid current. Cheers Andy |