Bush Ireland 3 band 1955 Model 177 - UK Vintage Radio Repair and Restoration Discussion Forum

Mike. Watterson · 18th Jul 2019, 2:12 pm

This is Ewan's set. LW, MW, SW. No magic eye. Four knobs and dual scale (larger scale is MW only). Photos later.

Possibly ECH42, EF41, EBC41, EL41, EZ40. The 1952 Bush EBS31 has that line up.

The metal work of the chassis is the same as AC41, except that has an EBF80 replacing the EF41 and EBC41. You can see the hole in the chassis.
Made in late 1954 or early 1955.
The valve line up like an E version of the U series AC34, though its chassis doesn't match (there are versions of that chassis with an addtional UF41 RF preamp and 3 gang capacitor).
Obviously late 1954 early 1955 was when Bush UK would have been changing to VHF for "better sets" and indeed most makers for the Irish market diverge after 1954 (Pilot, Pye, Bush are the obvious ones).

About 9 paper caps need replaced. One checked at random had about 12uA @ 5V and 1mA at 30V!

I've looked in Trader, R&TVS, The Shrubbery and the Radio Museum. The AC41 with short superhet lineup seems to be the only matching metalwork. The AC34, while series U type valves and slightly different chassis seems a similar idea.

Any thoughts? Or is it just a typical UK VHF era AM only Irish market model (as real export models had SW rather than LW). The EBS35 seems to be roughly the AC34 with an extra UF41 preamp, though an E series version has been mentioned.

paulsherwin · 18th Jul 2019, 3:06 pm

Pye made similar short superhets with mixed B8A/B9A lineups.

Mike. Watterson · 18th Jul 2019, 3:20 pm

Yes, though this is not using the EBF80. The empty hole on the AC41 has the EBC41 and the EBF80 position has the EF41.

Loads of models are ECH42, EF41, EBC41, EL41, EZ40.

I'm curious, because I can't find a photo of a UK or Export mode using this metal work (same as AC41 metal work) with U or E series valves in the holes.
Obviously the AC41 uses a chassis punched for the EBC41 or UBC41, though perhaps they dropped the EBC41 during the design stage.

The VHF41 isn't a hugely different chassis (obviously has the 2 x EF80 VHF head piggy-backed) and the two extra IFTs. It probably has the EABC80 in that location. However even allowing for the FM 10.7 IFTs behind the AM ones, and Novals, it's not really similar. The Irish model does look just like the AC41 metal work.
Back sore, so lying down to read a book. So maybe no photos today.

I gave away a different Irish Bush, AM only, more the case style of the UK EBS35 / VHF55. The BS35 https://www.radiomuseum.org/r/bushirl_bs35_142.html It's U series and is not the same metalwork as Ewan's model, it's like the EBS35, just the LW replacing a SW.

There is an Irish version of the AC41, the BS21 https://www.radiomuseum.org/r/bushirl_bs21.html it's also the short superhet like the AC41. No doubt this is the same metalwork but full superhet, so no empty hole.

Mike. Watterson · 18th Jul 2019, 5:51 pm

10nF paper dielectric from EBC41 anode to 470K EL41 grid bias was 4.5mA @ 20V!

Maybe it's globaly warming or the damp Irish air. Anyway, my theory is that the "so called" "That Capacitor" is NOT the only one to replace before power on. There is no need to replace Silver Mica, Polystyrene, Polyester or even Electrolytics unless they are known to be faulty. The HT Electrolytics are relatively easy to check and reform. The others at audio cathodes and on FM sets the discriminator (I find it the most commonly faulty one).

The chassis is 177, but rear panel has "BI 21", all the Irish Bush sets I've seen before are "BS nn", so though this is a cheaper looking black painted case, it's using EF41 and EBC41 instead of the EBF80 of the "BS 21" short superhet. I don't think "S" means short.

Another 7 or 8 caps to go. The six wires from chassis to front (HT, Anode, 2 x feedback and panel lamps) are all perished rubber. Odd when PVC was already widespread, I guess it was cheap. PVC is actually a Victorian discovery but it wasn't till 1926 that plasticisers were developed. PVC wire insulation existed in 1927 and some WWII, late '40s and early '50s radios do have PVC. Common in radio wiring by 1955.
Polyester was available from 1942, but the low cost of paper meant that though by the mid 1930s they knew paper had a rubbish life as a dielectric (10 to 12 years), it was only some makers that used it for capacitors in late 1950s. I'm not sure when first used for recording tape and photographic film.

Mike. Watterson · 18th Jul 2019, 7:03 pm

Here are some photos

The 10nF to volume control from IFT replaced by 10nF 1kV ceramic.
The 10nF with 4.5mA leakage at 20V, between EBC41 anode and the EL41 grid bias and grid stopper has a purple arrow.

The changer is a fresh looking Haltron 6C9, it's not the same thing as an ECH42, but they do work interchangeably (tested that in several sets a year or so ago).

The drive cord was falling off the drum due to the tuning cap chassis being twisted on the main chassis. I've wedged a piece of plastic that I'll replace with rubber.

Mike. Watterson · 20th Jul 2019, 7:36 pm

As far as I can make out there is feedback from the EBC41 Anode (and thus EL41 input) to the audio output transformer. Except the wire was snipped and taped. The AC35, AC41 etc don't have this. It does seem to be a feature of the VHF41 and other later AM/FM UK Bush models using a step up winding on the secondary. The transformer looks like a replacement. It has an open circuit connection that did have the feedback wire once (about 1cm of yellow wire). The EL41 anode and HT is across a primary measuring about 85 Ohms. The next tag is 215 Ohms approximately and marked CT on paper sleeve. It doesn't look ever soldered.

I think the DC resistance of that size O/P transformer should between 300 and 500 Ohms. The Bush VHFnn series are all 410 Ohm on the trader sheets. The AC41 is 410 and the AC34 is 500 Ohms. Which backs up my experience.

The transformer looks like a replacement "universal" type and is obviously wired wrong.
So with 85 Ohm DC load and totally leaky input capacitor (less than 1.5K Ohms!), no wonder the EL41 glass had collapsed. I wonder did Ewan keep that?

The two windings together, if phase is correct would be about 300 Ohms. Maybe I have something more suitable in my box of O/P spares.

crackle · 20th Jul 2019, 9:09 pm

I am a bit confused, have I missed something, why is the title "Model 177" and the back of the radio says type BI 21.
Mike

Mike. Watterson · 20th Jul 2019, 9:51 pm

The Chassis is 177.
There is no 100% assurance that the back is correct, though it probably is.
I agree the radio probably is BI21, though there is a BS21. Bush Ireland models seem to have been BS. This is the first "BI" I've seen.

I've found an audio o/p transformer from a scrapped Currys taperecorder. It has a feedback tap on the primary, however that should work without additional DC isolation.

AD360 Rob · 21st Jul 2019, 10:20 am

Quote:

Originally Posted by Mike. Watterson

Here are some photos

The drive cord was falling off the drum due to the tuning cap chassis being twisted on the main chassis. I've wedged a piece of plastic that I'll replace with rubber.

You'll probably find there are rubber grommets under the tuning cap that will have hardened or perished, this is very common in bush (and other) sets. Replace these and your tuning cap will be stable and correctly positioned once more. I use standard wiring grommets to fit an 8mm chassis hole with a 5.5mm inner hole diameter. easily obtainable on ebay and other websites

Mike. Watterson · 21st Jul 2019, 10:22 am

I've now unscrewed the scale, chassis plates, speaker sockets/switch and speaker baffle.
Popped off the two brass effect edgings to get the plastic cloth off the knob area and the speaker baffle. There are flight holes on the baffle panel so it needs treated. There are now only wood screws and wood on the baffle board and the main case, so I will heat treat from the bare areas of case and both sides of baffle. Eggs aren't laid on painted areas anyway. Then soak in the wood preservative / bug killer, though a few days in paraffin or diesel is nearly as good. The main thing is to kill eggs on surface and deprive the grubs already munching (2 to 3 years) of moisture and oxygen. A good dose of varnish after the preservative has dried is good.

The case has a triangle of surface plywood / veneer missing at the side. I'll either use a piece of veneer or plastic wood. The case is finished in black with no visible wood grain and two brass or brass effect strips.

Mike. Watterson · 21st Jul 2019, 10:29 am

Quote:

Originally Posted by AD360 Rob

You'll probably find there are rubber grommets under the tuning cap that will have hardened or perished, this is very common in bush (and other) sets.

Yes, I have loads of grommets. The tuning capacitors can sometimes be hard to unscrew and de-solder so sometimes I wedge and glue stiff plastic foam (not the sponge stuff) under the base. The screws and grommets are accessible on this as the wave-change switch and coil sets are mounted there as well as a secondary plate under the chassis.

dazzlevision · 21st Jul 2019, 10:31 am

Quote:

Originally Posted by Mike. Watterson

The Chassis is 177.
There is no 100% assurance that the back is correct, though it probably is.
I agree the radio probably is BI21, though there is a BS21. Bush Ireland models seem to have been BS. This is the first "BI" I've seen.

The serial number plate on all Bush sets is of the form xxx/xxxxx. According to a mention in an issue of RBM's "Service Skill" (a publication intended for their dealer's service departments), the first three digits indicate the model number of the set into which the chassis is fitted.

Mike. Watterson · 21st Jul 2019, 10:36 am

Yes, the 177 are the three digits in front of the slash. The Radiomuseum database has fields for outer or advertised model name, chassis model label and variant.

Mike. Watterson · 21st Jul 2019, 5:06 pm

The cabinet needs some work and rear of scale needs cleaned.

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Several different generations of flight holes.

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The cloth is plastic, though the smaller part has some flight holes.

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I think the upper part isn't glued, but lower part glue has failed.

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The edges at the scale are clipped on.

There is also a small thin plywood baffle / spacer between the main panel (shown) and the speaker.

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Some flight holes here too.
It's also clear from the cloth and baffle that the badge has lost a pin and should be at an angle. I'll drill a shallow hole and epoxy a new pin in place to stop the badge moving.

One side also has a mix of old and "fresh" flight holes.

Mike. Watterson · 22nd Jul 2019, 7:11 pm

Caps changed today. The tuning label on the rear of the drum has AC31. It's like a mix of AC31, AC34, AC41 and VHF41.
Similar feedback to the VHF41.
LW was lively with a wire aerial. It wouldn't work with a MW/LW switched loop.
MW & SW was dead, not even static.
Injecting from sig generator proved that the LO was working on MW & SW. Also there was pickup if the aerial was connected direct to the tuning cap. So the RF aerial switching to the MW and SW RF matching coils was suspect.
Eventually MW & SW came to life about an hour after Ewan left!
The function of the various paper caps was figured out and noted in the repair log book mostly with reference to the AC34, valve base, HT, AGC line, IFTs etc. Fortunately the value markings didn't scrape off with the dirtied wax.

The cathode resistor on the EL41 was pretty cooked. It measured 97 Ohms. It looked a little like 100, but I thought on balance the middle band might have once been grey so 180 Ohms. Examination of various UL41 and EL41 circuits confirmed by suspicion that 180 was feasible, but not 100. A value of 220 Ohms is common too. I couldn't find any suitable 180, or resistors to use in parallel with sufficient power rating till I found a large 30 and 150 soldered in series in a drawer, so those were fitted.

Mike. Watterson · 22nd Jul 2019, 10:16 pm

This time of year the UK MW only coming in this time of night (dusk = 10pm).
At least I've a signal generator or three.
Now LW & MW working with loop (either my dual band switched one, or the MW only USA ex set with about 2.5mH switched in for LW). The SW is fine on the wire aerial, which reduces MW & LW interference if it's connected to chassis when MW/LW loops are used on MW/LW.
SW more lively now at longer wavelength.

Next job is the case.

18th Jul 2019, 2:12 pm	#1
Mike. Watterson Heptode Join Date: Dec 2014 Location: Limerick, Ireland. Posts: 901	Bush Ireland 3 band 1955 Model 177 This is Ewan's set. LW, MW, SW. No magic eye. Four knobs and dual scale (larger scale is MW only). Photos later. Possibly ECH42, EF41, EBC41, EL41, EZ40. The 1952 Bush EBS31 has that line up. The metal work of the chassis is the same as AC41, except that has an EBF80 replacing the EF41 and EBC41. You can see the hole in the chassis. Made in late 1954 or early 1955. The valve line up like an E version of the U series AC34, though its chassis doesn't match (there are versions of that chassis with an addtional UF41 RF preamp and 3 gang capacitor). Obviously late 1954 early 1955 was when Bush UK would have been changing to VHF for "better sets" and indeed most makers for the Irish market diverge after 1954 (Pilot, Pye, Bush are the obvious ones). About 9 paper caps need replaced. One checked at random had about 12uA @ 5V and 1mA at 30V! I've looked in Trader, R&TVS, The Shrubbery and the Radio Museum. The AC41 with short superhet lineup seems to be the only matching metalwork. The AC34, while series U type valves and slightly different chassis seems a similar idea. Any thoughts? Or is it just a typical UK VHF era AM only Irish market model (as real export models had SW rather than LW). The EBS35 seems to be roughly the AC34 with an extra UF41 preamp, though an E series version has been mentioned.

18th Jul 2019, 3:06 pm	#2
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,960	Re: Bush Irl 3 band 1955 Model 177 Pye made similar short superhets with mixed B8A/B9A lineups.

18th Jul 2019, 3:20 pm	#3
Mike. Watterson Heptode Join Date: Dec 2014 Location: Limerick, Ireland. Posts: 901	Re: Bush Irl 3 band 1955 Model 177 Yes, though this is not using the EBF80. The empty hole on the AC41 has the EBC41 and the EBF80 position has the EF41. Loads of models are ECH42, EF41, EBC41, EL41, EZ40. I'm curious, because I can't find a photo of a UK or Export mode using this metal work (same as AC41 metal work) with U or E series valves in the holes. Obviously the AC41 uses a chassis punched for the EBC41 or UBC41, though perhaps they dropped the EBC41 during the design stage. The VHF41 isn't a hugely different chassis (obviously has the 2 x EF80 VHF head piggy-backed) and the two extra IFTs. It probably has the EABC80 in that location. However even allowing for the FM 10.7 IFTs behind the AM ones, and Novals, it's not really similar. The Irish model does look just like the AC41 metal work. Back sore, so lying down to read a book. So maybe no photos today. I gave away a different Irish Bush, AM only, more the case style of the UK EBS35 / VHF55. The BS35 https://www.radiomuseum.org/r/bushirl_bs35_142.html It's U series and is not the same metalwork as Ewan's model, it's like the EBS35, just the LW replacing a SW. There is an Irish version of the AC41, the BS21 https://www.radiomuseum.org/r/bushirl_bs21.html it's also the short superhet like the AC41. No doubt this is the same metalwork but full superhet, so no empty hole. Last edited by Mike. Watterson; 18th Jul 2019 at 3:30 pm. Reason: Short Super

18th Jul 2019, 5:51 pm	#4
Mike. Watterson Heptode Join Date: Dec 2014 Location: Limerick, Ireland. Posts: 901	Re: Bush Irl 3 band 1955 Model 177 10nF paper dielectric from EBC41 anode to 470K EL41 grid bias was 4.5mA @ 20V! Maybe it's globaly warming or the damp Irish air. Anyway, my theory is that the "so called" "That Capacitor" is NOT the only one to replace before power on. There is no need to replace Silver Mica, Polystyrene, Polyester or even Electrolytics unless they are known to be faulty. The HT Electrolytics are relatively easy to check and reform. The others at audio cathodes and on FM sets the discriminator (I find it the most commonly faulty one). The chassis is 177, but rear panel has "BI 21", all the Irish Bush sets I've seen before are "BS nn", so though this is a cheaper looking black painted case, it's using EF41 and EBC41 instead of the EBF80 of the "BS 21" short superhet. I don't think "S" means short. Another 7 or 8 caps to go. The six wires from chassis to front (HT, Anode, 2 x feedback and panel lamps) are all perished rubber. Odd when PVC was already widespread, I guess it was cheap. PVC is actually a Victorian discovery but it wasn't till 1926 that plasticisers were developed. PVC wire insulation existed in 1927 and some WWII, late '40s and early '50s radios do have PVC. Common in radio wiring by 1955. Polyester was available from 1942, but the low cost of paper meant that though by the mid 1930s they knew paper had a rubbish life as a dielectric (10 to 12 years), it was only some makers that used it for capacitors in late 1950s. I'm not sure when first used for recording tape and photographic film.

18th Jul 2019, 7:03 pm	#5
Mike. Watterson Heptode Join Date: Dec 2014 Location: Limerick, Ireland. Posts: 901	Re: Bush Irl 3 band 1955 Model 177 Here are some photos The 10nF to volume control from IFT replaced by 10nF 1kV ceramic. The 10nF with 4.5mA leakage at 20V, between EBC41 anode and the EL41 grid bias and grid stopper has a purple arrow. The changer is a fresh looking Haltron 6C9, it's not the same thing as an ECH42, but they do work interchangeably (tested that in several sets a year or so ago). The drive cord was falling off the drum due to the tuning cap chassis being twisted on the main chassis. I've wedged a piece of plastic that I'll replace with rubber. Attached Thumbnails

20th Jul 2019, 7:36 pm	#6
Mike. Watterson Heptode Join Date: Dec 2014 Location: Limerick, Ireland. Posts: 901	Re: Bush Ireland 3 band 1955 Model 177 As far as I can make out there is feedback from the EBC41 Anode (and thus EL41 input) to the audio output transformer. Except the wire was snipped and taped. The AC35, AC41 etc don't have this. It does seem to be a feature of the VHF41 and other later AM/FM UK Bush models using a step up winding on the secondary. The transformer looks like a replacement. It has an open circuit connection that did have the feedback wire once (about 1cm of yellow wire). The EL41 anode and HT is across a primary measuring about 85 Ohms. The next tag is 215 Ohms approximately and marked CT on paper sleeve. It doesn't look ever soldered. I think the DC resistance of that size O/P transformer should between 300 and 500 Ohms. The Bush VHFnn series are all 410 Ohm on the trader sheets. The AC41 is 410 and the AC34 is 500 Ohms. Which backs up my experience. The transformer looks like a replacement "universal" type and is obviously wired wrong. So with 85 Ohm DC load and totally leaky input capacitor (less than 1.5K Ohms!), no wonder the EL41 glass had collapsed. I wonder did Ewan keep that? The two windings together, if phase is correct would be about 300 Ohms. Maybe I have something more suitable in my box of O/P spares.

20th Jul 2019, 9:09 pm	#7
crackle Rest in Peace Join Date: Mar 2011 Location: Basildon, Essex, UK. Posts: 4,100	Re: Bush Ireland 3 band 1955 Model 177 I am a bit confused, have I missed something, why is the title "Model 177" and the back of the radio says type BI 21. Mike

20th Jul 2019, 9:51 pm	#8
Mike. Watterson Heptode Join Date: Dec 2014 Location: Limerick, Ireland. Posts: 901	Re: Bush Ireland 3 band 1955 Model 177 The Chassis is 177. There is no 100% assurance that the back is correct, though it probably is. I agree the radio probably is BI21, though there is a BS21. Bush Ireland models seem to have been BS. This is the first "BI" I've seen. I've found an audio o/p transformer from a scrapped Currys taperecorder. It has a feedback tap on the primary, however that should work without additional DC isolation.

21st Jul 2019, 10:22 am	#10
Mike. Watterson Heptode Join Date: Dec 2014 Location: Limerick, Ireland. Posts: 901	Re: Bush Ireland 3 band 1955 Model 177 I've now unscrewed the scale, chassis plates, speaker sockets/switch and speaker baffle. Popped off the two brass effect edgings to get the plastic cloth off the knob area and the speaker baffle. There are flight holes on the baffle panel so it needs treated. There are now only wood screws and wood on the baffle board and the main case, so I will heat treat from the bare areas of case and both sides of baffle. Eggs aren't laid on painted areas anyway. Then soak in the wood preservative / bug killer, though a few days in paraffin or diesel is nearly as good. The main thing is to kill eggs on surface and deprive the grubs already munching (2 to 3 years) of moisture and oxygen. A good dose of varnish after the preservative has dried is good. The case has a triangle of surface plywood / veneer missing at the side. I'll either use a piece of veneer or plastic wood. The case is finished in black with no visible wood grain and two brass or brass effect strips.

21st Jul 2019, 10:36 am	#13
Mike. Watterson Heptode Join Date: Dec 2014 Location: Limerick, Ireland. Posts: 901	Re: Bush Ireland 3 band 1955 Model 177 Yes, the 177 are the three digits in front of the slash. The Radiomuseum database has fields for outer or advertised model name, chassis model label and variant.

21st Jul 2019, 5:06 pm	#14
Mike. Watterson Heptode Join Date: Dec 2014 Location: Limerick, Ireland. Posts: 901	Re: Bush Ireland 3 band 1955 Model 177 The cabinet needs some work and rear of scale needs cleaned. Several different generations of flight holes. The cloth is plastic, though the smaller part has some flight holes. I think the upper part isn't glued, but lower part glue has failed. The edges at the scale are clipped on. There is also a small thin plywood baffle / spacer between the main panel (shown) and the speaker. Some flight holes here too. It's also clear from the cloth and baffle that the badge has lost a pin and should be at an angle. I'll drill a shallow hole and epoxy a new pin in place to stop the badge moving. One side also has a mix of old and "fresh" flight holes.

22nd Jul 2019, 7:11 pm	#15
Mike. Watterson Heptode Join Date: Dec 2014 Location: Limerick, Ireland. Posts: 901	Re: Bush Ireland 3 band 1955 Model 177 Caps changed today. The tuning label on the rear of the drum has AC31. It's like a mix of AC31, AC34, AC41 and VHF41. Similar feedback to the VHF41. LW was lively with a wire aerial. It wouldn't work with a MW/LW switched loop. MW & SW was dead, not even static. Injecting from sig generator proved that the LO was working on MW & SW. Also there was pickup if the aerial was connected direct to the tuning cap. So the RF aerial switching to the MW and SW RF matching coils was suspect. Eventually MW & SW came to life about an hour after Ewan left! The function of the various paper caps was figured out and noted in the repair log book mostly with reference to the AC34, valve base, HT, AGC line, IFTs etc. Fortunately the value markings didn't scrape off with the dirtied wax. The cathode resistor on the EL41 was pretty cooked. It measured 97 Ohms. It looked a little like 100, but I thought on balance the middle band might have once been grey so 180 Ohms. Examination of various UL41 and EL41 circuits confirmed by suspicion that 180 was feasible, but not 100. A value of 220 Ohms is common too. I couldn't find any suitable 180, or resistors to use in parallel with sufficient power rating till I found a large 30 and 150 soldered in series in a drawer, so those were fitted.

22nd Jul 2019, 10:16 pm	#16
Mike. Watterson Heptode Join Date: Dec 2014 Location: Limerick, Ireland. Posts: 901	Re: Bush Ireland 3 band 1955 Model 177 This time of year the UK MW only coming in this time of night (dusk = 10pm). At least I've a signal generator or three. Now LW & MW working with loop (either my dual band switched one, or the MW only USA ex set with about 2.5mH switched in for LW). The SW is fine on the wire aerial, which reduces MW & LW interference if it's connected to chassis when MW/LW loops are used on MW/LW. SW more lively now at longer wavelength. Next job is the case.