UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Radio (domestic)

Notices

Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only.

Reply
 
Thread Tools
Old 17th Nov 2020, 8:56 pm   #61
Sinewave
Octode
 
Sinewave's Avatar
 
Join Date: May 2016
Location: Oxfordshire/Bucks borders, UK.
Posts: 1,236
Default Re: Bush AC41

So I relflowed what looks like to be a dry joint with C10 and the mod tone can be heard, but very quietly, it's still much stronger further along the scale. If I leave it at 500m and adjust the generator its stronger at about 470k which is the intermediate frequency. So something's still a little out somewhere.
__________________
Avometer, vintage Fluke and Marconi collector.

At 144-146.00Mhz, keeping one wavelength apart.
Sinewave is offline   Reply With Quote
Old 17th Nov 2020, 10:42 pm   #62
Sinewave
Octode
 
Sinewave's Avatar
 
Join Date: May 2016
Location: Oxfordshire/Bucks borders, UK.
Posts: 1,236
Default Re: Bush AC41

Despite that, there are a handful of stations I am picking up reasonably well, despite using some speaker wire as an antenna which isn't quite properly placed. I'm also adjusting the MW cores whilst tuning to a station, without the generator and comparing it to another working radio, since on MW the mod tone isn't quite strong where it should be.

I don't have a proper dummy antenna, so for now I'm just using a 0.1uf cap.
__________________
Avometer, vintage Fluke and Marconi collector.

At 144-146.00Mhz, keeping one wavelength apart.
Sinewave is offline   Reply With Quote
Old 18th Nov 2020, 3:10 pm   #63
cathoderay57
Octode
 
Join Date: Oct 2017
Location: Bristol, UK.
Posts: 1,129
Default Re: Bush AC41

I've attached a sketch of the dummy aerial used for medium frequencies on the Avo All-Wave Oscillator. Jerry
Attached Files
File Type: pdf Dummy Aerial.pdf (33.6 KB, 16 views)
cathoderay57 is offline   Reply With Quote
Old 18th Nov 2020, 3:44 pm   #64
ms660
Dekatron
 
ms660's Avatar
 
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 9,681
Default Re: Bush AC41

A standard dummy antenna should be fed from a 10 Ohm impedance, that means a matching network should be fitted if the output impedance of the signal generator is more than that.

Details for connecting to a signal generator that has an output impedance of 75 Ohms are given in the link.

Lawrence.
Attached Files
File Type: pdf Advance Components Termination Pad TP1B.pdf (224.3 KB, 15 views)
ms660 is offline   Reply With Quote
Old 19th Nov 2020, 5:10 pm   #65
Sinewave
Octode
 
Sinewave's Avatar
 
Join Date: May 2016
Location: Oxfordshire/Bucks borders, UK.
Posts: 1,236
Default Re: Bush AC41

Thanks. I'll have to see when I'll be able to get any inductors.

In the meanwhile, I do have an Avo All wave, I can't remember how 'ready' it is, but maybe I could use the dummy antenna with my Marconi TF144H/4S set.
__________________
Avometer, vintage Fluke and Marconi collector.

At 144-146.00Mhz, keeping one wavelength apart.
Sinewave is offline   Reply With Quote
Old 20th Nov 2020, 9:21 pm   #66
Sinewave
Octode
 
Sinewave's Avatar
 
Join Date: May 2016
Location: Oxfordshire/Bucks borders, UK.
Posts: 1,236
Default Re: Bush AC41

Ok, my Avo all wave dummy antenna is working fine.

I checked C10, will need to make some other checks and work out why I can't get the tone where I should on the L9 and L4 adjustments.
__________________
Avometer, vintage Fluke and Marconi collector.

At 144-146.00Mhz, keeping one wavelength apart.
Sinewave is offline   Reply With Quote
Old 21st Nov 2020, 12:31 pm   #67
John10b
Octode
 
Join Date: Nov 2016
Location: Aberaeron, Ceredigion, Wales, UK.
Posts: 1,742
Default Re: Bush AC41

Glad you are making good progress, if you canít ďpeak upĒ the IF, it is probably one of the capacitors across the coil, as mentioned earlier.
You can gently remove the IF Can, and take a look at the capacitors, it could be a bad joint on the rivet of the capacitor or, as I have found in the past, a fractured lead from the capacitor itself.
John
John10b is offline   Reply With Quote
Old 21st Nov 2020, 1:29 pm   #68
Sinewave
Octode
 
Sinewave's Avatar
 
Join Date: May 2016
Location: Oxfordshire/Bucks borders, UK.
Posts: 1,236
Default Re: Bush AC41

Thanks John.

The IF peaks, but it's the MW RF which doesn't. Do you think that there could still a hidden issue in IF linked to the RF side not peaking on MW? I can peak on LW fine.
__________________
Avometer, vintage Fluke and Marconi collector.

At 144-146.00Mhz, keeping one wavelength apart.
Sinewave is offline   Reply With Quote
Old 21st Nov 2020, 3:58 pm   #69
John10b
Octode
 
Join Date: Nov 2016
Location: Aberaeron, Ceredigion, Wales, UK.
Posts: 1,742
Default Re: Bush AC41

Didnít read the thread properly, I would suggest the IF,s are ok, from what you say, thatís good. So the problem could be switch contact or one of the capacitors across the coil, I think this has been already suggested, so more fault finding is required, so keep going you have made excellent progress so far, now time for Rugby.
John
John10b is offline   Reply With Quote
Old 21st Nov 2020, 5:21 pm   #70
John10b
Octode
 
Join Date: Nov 2016
Location: Aberaeron, Ceredigion, Wales, UK.
Posts: 1,742
Default Re: Bush AC41

I should have said you should try adjusting C10 , as suggested by Jerry first, you may not have a fault. I have the Bush Service Manual not the Trader sheet so the components are numbered differently.
John
John10b is offline   Reply With Quote
Old 21st Nov 2020, 9:29 pm   #71
Sinewave
Octode
 
Sinewave's Avatar
 
Join Date: May 2016
Location: Oxfordshire/Bucks borders, UK.
Posts: 1,236
Default Re: Bush AC41

I think there's a few different drawings about. From what I see on mine, C10 is a fixed value, 515pF?
__________________
Avometer, vintage Fluke and Marconi collector.

At 144-146.00Mhz, keeping one wavelength apart.
Sinewave is offline   Reply With Quote
Old 21st Nov 2020, 10:42 pm   #72
cathoderay57
Octode
 
Join Date: Oct 2017
Location: Bristol, UK.
Posts: 1,129
Default Re: Bush AC41

Do you have the means to test the value of C10, or substitute a replacement capacitor (a 470pF in parallel with 47pF is close enough, preferably silver mica). Jerry
cathoderay57 is offline   Reply With Quote
Old 22nd Nov 2020, 1:23 am   #73
Sinewave
Octode
 
Sinewave's Avatar
 
Join Date: May 2016
Location: Oxfordshire/Bucks borders, UK.
Posts: 1,236
Default Re: Bush AC41

I've got a capacitance range on my meter, but not a proper capacitor tester.

I do have the values you've suggested, but in film/foil.
__________________
Avometer, vintage Fluke and Marconi collector.

At 144-146.00Mhz, keeping one wavelength apart.
Sinewave is offline   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 1:31 am.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Copyright ©2002 - 2020, Paul Stenning.