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Old 10th Sep 2019, 9:36 pm   #1
Ronners
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Default Invicta VHF Aerial.

Hi there folks just acquired a 1950s Invicta type 60rg the set is trying its best to give a radio signal on LW and MW although volume is low in spite of putting a cable in the Ariel socket at the back. In the middle of the back cover is a hole marked vhf ariel but when i remove the back nothing there can anyone tell me where to connect a vhf ariel? Best regards Ron H.
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Old 10th Sep 2019, 10:54 pm   #2
rambo1152
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Default Re: Invicta VHF Aerial.

Sounds strange.

According to the Radio Museum the Invicta model 60 is a console version of the model 38 table-top set, and they are MW/LW/VHF, but according to this auction listing
https://www.worthpoint.com/worthoped...age-1775440512
the Model No 60 is a LW/MW/SW set.
The RG suffix might imply radiogram.
Perhaps you don't have the original back-cover.

Some pictures of the front, chassis, and back cover would help.
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Old 11th Sep 2019, 8:45 am   #3
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Default Re: Invicta VHF Aerial.

Cheers Graham thanks for that I have looked closely on the tuning glass and the band selector and both say clearly Gram FM MW LW unfortunately I won't be taking it apart yet as I have bought it for a winter project and don't have room in my man cave at the moment. I was just trying to do a quick assessment as to what will be required what works and what doesn't etc. Best regards Ron H.
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Old 11th Sep 2019, 9:12 am   #4
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Default Re: Invicta VHF Aerial.

I see a valve marked 'EABC80' in one of your pictures. That pretty much means the set has VHF/FM coverage.

Where does the screened cable with the 2 white plugs at the left of the picture go? To a pickup?
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Old 11th Sep 2019, 9:34 am   #5
Mr 1936
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Default Re: Invicta VHF Aerial.

I have a Ferguson 385RG Radiogram from the mid 1950's which bears a remarkable resemblance to the picture you posted. Which is rather strange as I think Invicta was part of Pye in Cambridge whereas Ferguson were part of the Thorn Group.

Anyway, typical of the time would be a VHF aerial socket with two closely spaced sockets, one a little larger than the other. Stapled inside the cabinet would be a "get you going" shortened and bent dipole with a flying lead and 2 pin plug plugged into said socket. If this wasn't up to the job, you could unplug it and substitute a better loft or outdoor dipole using 75 ohm coax. Bear in mind though that Invicta may have adopted a different setup.

On my 385 the LW/MW (AM) aerial is a ferrite rod, which were just coming into use in that period. There is no external AM aerial option. The rod can be rotated somewhat by a cunning toothed wheel accessible next to the autochanger. This avoided the problem of being unlucky and having the null of the aerial coinciding with your favourite station, as it wan't very practical to rotate the whole radiogram !

Good luck with the Resto !
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Old 11th Sep 2019, 9:46 am   #6
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Default Re: Invicta VHF Aerial.

The chassis is very similar to the Pam 714, the rotary controls are different but from the photo of the chassis in the Invicta they look very much alike.
There is a round hole in the rear apron of the chassis near the tuning gang, in the Pam that is a coax socket for the VHF aerial.

If you post more photos of the chassis it may be possible to confirm the similarity. Pam and Invicta were owned by Pye in the 1950/60/70ís.

The makers manual and Trader sheet for the Pam 714 are available from the service data at the top of the page.
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Old 11th Sep 2019, 10:10 am   #7
Ronners
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Default Re: Invicta VHF Aerial.

The two screened white plugs go to the A&E sockets on the rear card. Cheers.

Many thanks to you all for your helpful comments I will try and have a look at it at the weekend. Best regards Ron H.
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Old 11th Sep 2019, 4:21 pm   #8
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Default Re: Invicta VHF Aerial.

Ah on closer inspection the two white screened plugs go to an antenna coiled round the back card terminating in a short bare wire I attached a length of wire to this and the other end to an old vhf antenna now I can tune in around three programs but not very loud as with MW & LW the amp is fine as I now have the record player de seized and sort of working the lower white plug of the three goes to the ariel socket on the card and the E socket on the card to the chassis earth to the left. Any ideas how to improve volume. Best regards Ron H.
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Old 11th Sep 2019, 4:22 pm   #9
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Default Re: Invicta VHF Aerial.

Sorry earth chassis tab to the right.
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Old 11th Sep 2019, 4:30 pm   #10
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Default Re: Invicta VHF Aerial.

Be good to find out if the Pam 714 is nearly the same, then we would have a circuit and layout to help advise.
Photo of the Pam.
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Old 11th Sep 2019, 5:09 pm   #11
Ronners
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Default Re: Invicta VHF Aerial.

https://www.vintage-radio.net/forum/...6&d=1568218026
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Old 11th Sep 2019, 5:23 pm   #12
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Default Re: Invicta VHF Aerial.

That link returns invalid attachment.
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Old 11th Sep 2019, 6:08 pm   #13
Ronners
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Default Re: Invicta VHF Aerial.

OK Frank have the schematics but seem to have a problem posting them I will try again later Best regards Ron H.
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Old 11th Sep 2019, 6:19 pm   #14
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Default Re: Invicta VHF Aerial.

Please do not post circuits available on this site, and/or from Radiomuseum.
https://www.service-data.com/section.php/3926/1/60

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Old 11th Sep 2019, 7:14 pm   #15
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Default Re: Invicta VHF Aerial.

With the circuit you can start some simple fault finding. Check voltages and signal injection should point to the low output.
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Old 11th Sep 2019, 8:25 pm   #16
Ronners
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Default Re: Invicta VHF Aerial.

Thanks for that Frank I know how to do the voltages but not how to check signal injection as I am a newbie only started last winter but with the help of you guy's on here have learnt a lot I have a signal generator but don't know how that works as yet bought a eggham scope last year also but need to get my head round that also.its just a winter hobby I fancied now I am retired. Best regards Ron H.
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Old 11th Sep 2019, 8:41 pm   #17
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Default Re: Invicta VHF Aerial.

If you intend to fix more sets I would learn how to use the scope and sig gen if you already know how to test voltages.
Knowing your test equipment can make fixing sets much easier.

I always point newcomers to this web page, it gives years of knowledge in an easy to read format.https://www.vintage-radio.com/repair...ion/index.html
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Old 12th Sep 2019, 2:24 pm   #18
Ronners
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Default Re: Invicta VHF Aerial.

Many thanks for your helpful advice Frank I will check this site out. Best regards Ron H.
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