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Old 19th Apr 2019, 8:32 pm   #1
davidgem1406
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Join Date: Feb 2011
Location: Sheerness, Kent, UK.
Posts: 936
Default Bush VHF-41 Refurb.

I have recently completed refurbishing of a Bush VHF-41 chassis.
All the Hunts moulded capacitors have been replaced (The moulding was all cracked up or missing), including the FM tuner.

All electrolytic's replaced except the main smoother, that's fine and happy.
A number of out of speck resistors also replaced.
The EABC80 valve base was replaced.

The chassis is now completed and generally working. However I have 3 problems to solve.

First the drive cord has been replaced but things are not very clear as to attaching the 2 pointer carriers.
It just says "with the tuning gang at fully closed attach a temporary pointer" to align with the datum mark.

What I actually did was to fit the 2 pointer carriers to the drive cord.
First the AM carrier with the gang fully closed set to the datum line.
Then the FM carrier set to the datum line with the gang fully open.
That seems the only way it can be done.

So, to do the alignment for the AM we use the AM carrier set against the relevant frequencies as shown on the front of the chassis.
For the FM we also use the AM carrier but set it against the FM frequencies.

My question here being is this the correct way to do this. It seems to be the same result as using a temporary pointer.

Next the AM is working well and with plenty of volume but it seems to be rather poor in noise rejection as we have a sound like sizzling bacon in a pan over the whole band that is quite prominent even with the stronger stations.

Finally we have a problem with the FM, although this is working to be able to listen to, even the stronger signals, we have to have the volume at maximum. So the FM audio is well below any sensibly usable level.
I have read that these sets are known to have a low FM volume as opposed to the AM volume. However it surely cannot be as low as mine is.

I have checked all the valve voltages and they are what I would reasonably expect them to be against that given in the service sheet.

Some valves were low, they have been replaced. EABC80, ECH81, 2x EF80 All others tested good.

Any help and suggestions would be appreciated.

Best regards,
Dave
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