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 > Other Discussions > Homebrew Equipment

Notices

Homebrew Equipment A place to show, design and discuss the weird and wonderful electronic creations from the hands of individual members.

Reply
 
Thread Tools
Old 1st Mar 2019, 1:42 pm   #1
dave_n_t
Pentode
 
dave_n_t's Avatar
 
Join Date: Sep 2003
Location: Cheltenham, Gloucestershire, UK.
Posts: 142
Default IF 'liner' (alignment aid)

Stimulated by recent discussions of IF alignment aids, I knocked up the pictured aid using bits and pieces I had lying around.

It's based loosely on one I found described online, here

The major changes are:
i) I used transistor IFTs instead of ceramic resonators. I have lots of IFTs and precisely zero ceramic resonators at 470kHz.

ii) I tuned them to 470 kHz (which is more common in the UK than 455kHz)

iii) I used one of the spare 4011 gates with 100k 'linearising' feedback as the 'output' linear amplifier. I haven't checked on the shape of the output waveform, but I don't imagine it's critical.

iv) I powered it from an 'N' cell, using one of the cheap 1.5V to 5V step-up circuits available on eBay. Current drain is 23mA. The step-up circuit has the added benefit of a really dinky pilot LED; and the further benefit of providing a sensible use for all the 'N' cells I acquired from 1 shops as side-effects to buying batteries for my garage and car key fobs.

v) I didn't bother with an output level control (see below).

vi) I pre-set the modulation depth. Possibly 50%, but 'good enough'.

Housed in a plastic box, it radiates 470kHz (and harmonics...) like mad, so 'connecting' it it the receiver-under-repair will be quite easy!

Quite a fun thing, which should be a bit easier for quick alignment touch-ups than my full-sized sig. gen.
Attached Thumbnails
Click image for larger version

Name:	DSC00430.v01.jpg
Views:	184
Size:	73.5 KB
ID:	179233  
__________________
Dave Teague
dave_n_t is offline   Reply With Quote
Old 2nd Mar 2019, 1:09 am   #2
David G4EBT
Dekatron
 
David G4EBT's Avatar
 
Join Date: Feb 2003
Location: Cottingham, East Yorkshire, UK.
Posts: 3,519
Default Re: IF 'liner' (alignment aid)

Very neat Dave!

Back in 2017 I had a dabble with that circuit, simply out of interest, obtained all the bits from here and there and knocked up a PCB, but it was overtaken by other projects. Given that I have several functional signal generators, it made little sense to build it, other than the fact that I enjoy taking circuit designs (invariably other people's!) and turning them into finished projects.

https://www.vintage-radio.net/forum/...d.php?t=140451
__________________
David.
BVWS Member.
G-QRP Club member 1339.
David G4EBT is offline   Reply With Quote
Old 2nd Mar 2019, 9:21 am   #3
dave_n_t
Pentode
 
dave_n_t's Avatar
 
Join Date: Sep 2003
Location: Cheltenham, Gloucestershire, UK.
Posts: 142
Default Re: IF 'liner' (alignment aid)

David,
Thanks for that, and the pointer to the earlier discussion.


I have a number of other 'proper' sig gens, one of which is my normal choice for tweaking sets; but I do like making odd bits of stuff, as well as repairing, and stripping 'junk', when necessary. I find that I get a bit stale with just one of the 3 branches of activity.


dave
__________________
Dave Teague
dave_n_t is offline   Reply With Quote
Old 2nd Mar 2019, 11:32 pm   #4
Tractionist
Heptode
 
Join Date: Apr 2016
Location: Cheltenham, Gloucestershire, UK.
Posts: 522
Default Re: IF 'liner' (alignment aid)

Ha - you've got more SG's than I can shake a stick at Dave !!!
__________________
Red to red, black to black. Throw the switch and stand well back!
Tractionist is offline   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 10:35 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 - 2019, vBulletin Solutions, Inc.
Copyright ©2002 - 2019, Paul Stenning.