Racal RA-17: Help needed!

[Skywave]

Briefly, can anyone direct me to where I can get some detailed help on fault-finding on a Racal RA-17, please? Mine - which I've owned for ages - is proper poorly!

For now, I'm not going to be too specific as to what I've done / looked at / replaced / measured, etc. - just to say that it has a "front end" type fault. (Yeah, I know - the "front end" is half the set - what I'm trying to say is that it's not a PSU / AF / IF fault!).

I have a copy of the manual - which, yes, is helpful in places - but the nature of the problem is rather obscure. The manual doesn't doesn't dig down deep enough in its "fault-finding section"

There are quite a few Web Sites on the Net that talk about this receiver, but none of these (that I've found) are specific enough on known faults versus symptoms. (BTW: I am aware of the "Hunts capacitors" problem!)

Perhaps a member reading this might just have the experience I lack to fix it!
In this case, I'm quite happy to go into "PM" mode if things get too heavy / specialized / OT for this Forum - provided, or course, that Paul S is happy with this arrangement

Thank you.

Al / G8DLH

[XTC]

There are a few people who specialise in RA17s. I can't recall the names off-hand, but they may have a web presence.

You could check out Keith's Racal site. He used to have a email setup up the site, but that seems to have disappeared. The page here

http://www.recelectronics.demon.co.uk/ra17.htm

gives some information on problems towards the bottom.

RA17s are complicated, but not unapproachable and you can work through them systematically with a sig-gen, scope and meter. You need a decent scope and sig-gen.


When I bought mine, I also bought a scrap one - It's complete apart from the mains transformer and choke, and some bits of metal work. When the RA17 played up, checking the voltages against the given values in the fault finding section of the manual, I found a dead resistor in the 2nd VFO. RA17s are notorious for burned out resistors. I was going to swap the VFO complete, but checked the smooth running of the film scale first. One of the rollers was seized and was bent slightly when it was removed. I had a new one machined. Getting the film scale back was interesting and I experimented with a piece of 35mm camera film before risking the film scale. Then I substituted the VFOs and set the original aside tor repair. It worked well, and I left it.

As there's a lot of work in taking the VFO apart to get at the resistor, it makes sense to replace the resistors and caps in that area of the set with new, good quality components.

I'm not aware of fault finding tree. for the RA17, you just have to work through the set systematically, maybe identifying the unit causing the problem, and then the component.

The real problem area is the 37.5 and 40MHz filters. They don't often cause problems, but if they do, say If a mica cap has failed in one of them, they need to be realigned, and that requires a special wobbulator unit or a sweep generator and scope, because they are not simply peaked, they have to have a particular response profile.

Colomor used to sell spare parts and some complete salvaged units.

HTH.

Pete.

[Skywave]

Originally Posted by XTC

You could check out Keith's Racal site. He used to have a email setup up the site, but that seems to have disappeared. The page here

http://www.recelectronics.demon.co.uk/ra17.htm

gives some information on problems towards the bottom.

RA17s are complicated, but not unapproachable and you can work through them systematically with a sig-gen, scope and meter. You need a decent scope and sig-gen.

Pete.

Thank you for your valued response.
I have edited the quote above simply for brevity and as an aide-de-memoir for this reply.

Yes, I'm sure that I've looked at Keith's Racal site - but I didn't find the depth of analysis that I think I need. I will look again to be sure.
Thanks for the suggestion.

A little detail: some of it is approximate for the sake of brevity.

At present, the test equip. I am using is a Marconi 2022C sig. gen., a Tek 467 'scope and the usual other "tools". I say "at present" since ultimately I intend / will need to re-align certain sections with a spectrum analyser (with tracking generator) and other exotic kit.
From the 2 - 3 Mc/s input, the set seems OK. (The set - at this point - will tune from 2 - 3 Mc/s using the 2nd. VFO and I/P from SG). The problem seems to be lack of drive from the 37.5 Mc/s BP filter to the mixer. Pro tem, I have re-aligned this, (and the two tuned ccts. before it that are after the harm. gen.), on exactly 37.5 This confirmed my suspicion: I fail to get anything like the stated drive level to the post BP filter mixer with the stated level I/P at the test point at the HG. The difference is susbstantial. (I refer to the spec. and procedure in the Racal maint. man.).
The insertion loss in the 37.5 Mc/s filter seems excessive - even when all 37.5 Mc/s circuits are tuned to 37.5 - (N.B none of the trimmers of the BPF are at "one end").

The 1st VFO produces O/P approx. in the correct freqs. (yet to be freq. cntr. checked) and what looks like correct level (except at its top end) . The 1 Mc/s xtal osc. O/P looks OK. So does the O/P from the HG. So, my attention is now focussed on that part from the HG O/P through to the 37.5 Mc. amps up to the O/P of the post BP filter-to-mixer. All valve d.c. voltages look OK in these areas.

Phew! I hoped that wasn't too complicated / obscure: it's been written from memory! I can't recall the valve no. references off-hand.

I wrote that lot for you - and just in case anyone else picks up this thread - and can feed in any relevant / helpful comments.

For the benefit of all readers, should I discover anything of "interest" in clearing this fault, I'll post it for archive record purposes on this Site. I'd hate anyone to have to go through the grief this fault is causing!

And again, thanks for your input.

Al / G8DLH

[jim_beacon]

Al,

if you have aligned the 37.5MHz filter to its center frequency, did all the stages have an effect on the tuning - a stage that seems to have a broad peak could indicate a fault.

ISTR that the filters are overcoupled, so that may also lead to alognment problems (hence the real need for a wobbulator).

As a final pointer, if you use a wobulator / spec analyser / sweep gen, be sure to keep the scan speed as low as possible (50Hz or preferably less), as fast sweeps will give erroneous results - this is why the Polyskop (recommened test gear for the RA17!) has a fixed scan rate of 50Hz.

Jim.

[Skywave]

Originally Posted by jim_beacon

Al,

if you have aligned the 37.5MHz filter to its center frequency, did all the stages have an effect on the tuning - a stage that seems to have a broad peak could indicate a fault.

ISTR that the filters are overcoupled, so that may also lead to alognment problems (hence the real need for a wobbulator).

As a final pointer, if you use a wobulator / spec analyser / sweep gen, be sure to keep the scan speed as low as possible (50Hz or preferably less), as fast sweeps will give erroneous results - this is why the Polyskop (recommened test gear for the RA17!) has a fixed scan rate of 50Hz.

Jim.

All the freq. sensitive elements did peak.

According to the manual, the 37.5 Mc. filt. is under-coupled (as I would expect - only single wave being passed), but the 40 Mc. filt is over-coupled to get the BP response.

Polyskop! Ah, that takes me back a very long way! Wonderful device!
Yes - I am aware of keeping the scan rate down to avoid distortion - a common error to make! - but thanks for the advice.

Eventually, I hope to use an Anritsu SA with its built-in TG (100Kc to 6.5 Gc)

And thank you for your contribution.

Al / G8DLH

[XTC]

Originally Posted by G8DLH

At present, the test equip. I am using is a Marconi 2022C sig. gen., a Tek 467 'scope and the usual other "tools". I say "at present" since ultimately I intend / will need to re-align certain sections with a spectrum analyser (with tracking generator) and other exotic kit.

Decent gear. You're not wading in with an Advance H1 and a Cossor scope.

Originally Posted by G8DLH

From the 2 - 3 Mc/s input, the set seems OK. (The set - at this point - will tune from 2 - 3 Mc/s using the 2nd. VFO and I/P from SG). The problem seems to be lack of drive from the 37.5 Mc/s BP filter to the mixer. Pro tem, I have re-aligned this, (and the two tuned ccts. before it that are after the harm. gen.), on exactly 37.5 This confirmed my suspicion: I fail to get anything like the stated drive level to the post BP filter mixer with the stated level I/P at the test point at the HG. The difference is susbstantial. (I refer to the spec. and procedure in the Racal maint. man.).
The insertion loss in the 37.5 Mc/s filter seems excessive - even when all 37.5 Mc/s circuits are tuned to 37.5 - (N.B none of the trimmers of the BPF are at "one end").

The 1st VFO produces O/P approx. in the correct freqs. (yet to be freq. cntr. checked) and what looks like correct level (except at its top end) . The 1 Mc/s xtal osc. O/P looks OK. So does the O/P from the HG. So, my attention is now focussed on that part from the HG O/P through to the 37.5 Mc. amps up to the O/P of the post BP filter-to-mixer. All valve d.c. voltages look OK in these areas.

Phew! I hoped that wasn't too complicated / obscure: it's been written from memory! I can't recall the valve no. references off-hand.

So, you've worked through the procedures in the manual, 5.6 and 5.8. You get nothing like the expected 1V out at TP3 for 2.5mV input at TP1.

You suspect that the 37.5MHz bandpass filter is excessively lossy.

If you inject a signal onto the grid of V6 to get 1V, you can tell what the output from the filter ought to be. If you have a healthy set for comparison, you can tell what the loss in the filter ought to be, and whether the filter is the problem.

Just guesses.

Try new known good valves of the correct CV types, not commercial equivalents for V4, 6, 8, 10. Check that the valve sockets are clean and the pins of the valves are clean.

Something wrong with the 37.5 MHz filter maybe. Leaky cap, corrosion on one of the preset plates, a dead spider across the turns of a coil. If you could swap in a different filter, it might be useful. Taking it out and eyeballing it isn't hard. Mica caps don't often fail, but when they do, they are a pain.

After that, I think you're down to checking the values of resistors in that area and so on. Dry joints, or joints that were never soldered when the set was made and have survived merely on contact. Caps leaking.

Originally Posted by G8DLH

I wrote that lot for you - and just in case anyone else picks up this thread - and can feed in any relevant / helpful comments.



For the benefit of all readers, should I discover anything of "interest" in clearing this fault, I'll post it for archive record purposes on this Site. I'd hate anyone to have to go through the grief this fault is causing!

And again, thanks for your input.

Al / G8DLH

I hope it's some use. RA17s are great sets, but when they go wrong, they are not for the faint hearted. The reason I bought the scrap set was a fear of having to sort out mine with no spares handy. It's already saved a lot of hassle.



Pete.

[Skywave]

Originally Posted by XTC

The reason I bought the scrap set was a fear of having to sort out mine with no spares handy. It's already saved a lot of hassle.

Pete.

Thanks for your reply.

Yes - there is no better way of quickly determining the area of a fault than by "known good" substitution.

However, I seem to be making some headway now. I have been able to get the specified throughput from the HG to the mixer - as referred to above. It was noteworthy that one of the trimmers in the 37.5 Mc filter seems jumpy on adjustment. I've also replaced a couple of valves "on spec." along the way, even though the voltages were about right. (You know & I know that the d.c. op. condx. don't tell you everything that's going on!).

The interesting (read: annoying) thing is that all this started with a working receiver. When I got it (cheap) several years ago, someone had "had a go" at it and converted the IF buffer to an NBFM detector using a PLL i.c., replaced the EB91 diodes with semi-conductor diodes, and other changes, including a redesign of the mode switch. Although the set worked, I thought it was time to tidy up this mess - and put it back to original. (No mean task!) Now all of this work is a "long way" from the front end, so you can imagine my surprise (read: irritation) when upon completion of this extensive restoration work, I found myself with a totally deaf set! +

I can only conclude that all that heaving about on the bench must have upset something mechanically - e.g. the trimmer or ??
My provisional re-alignment has resulted in different settings in various places (L's and C's)

The job's far from finished yet. (The calibrator is non-functional ). When it is, I shall make detailed notes (based on measurement) on signal levels at various points for future reference. In the absence of a spare set for bits (oh, joy!), seems the best I can do.

Will report again later - when there's more to tell.

Al /G8DLH

[XTC]

Originally Posted by G8DLH

Thanks for your reply.

Yes - there is no better way of quickly determining the area of a fault than by "known good" substitution.

However, I seem to be making some headway now. I have been able to get the specified throughput from the HG to the mixer - as referred to above. It was noteworthy that one of the trimmers in the 37.5 Mc filter seems jumpy on adjustment. I've also replaced a couple of valves "on spec." along the way, even though the voltages were about right. (You know & I know that the d.c. op. condx. don't tell you everything that's going on!).

The first RA17 to be delivered for approval didn't work. On a hunch, someone suggested that it was a resonance in one of the die-cast cavities causing the problem, so they cut a slot in the chassis with a band saw and that fixed it.

They were working at the edge of the technology so the sets can be a bit twitchy.

Numerous CV numbers for the same valve were issued for reasons. Often the construction changed although the nominal specs remained the same and there were odd factors which rarely made a difference, such as inter electrode capacitance, which could cause fun if used in the wrong place, such as in an RA17. Hence, if the set isn't well, stick to the specified CV types. That said, I've never seen any problem with commercial valves in my sets.

Given the equivalent of a 500K resistor across one of the tuned circuits in the filter, you'd have an interesting problem to solve.

Originally Posted by G8DLH

The interesting (read: annoying) thing is that all this started with a working receiver. When I got it (cheap) several years ago, someone had "had a go" at it and converted the IF buffer to an NBFM detector using a PLL i.c., replaced the EB91 diodes with semi-conductor diodes, and other changes, including a redesign of the mode switch. Although the set worked, I thought it was time to tidy up this mess - and put it back to original. (No mean task!) Now all of this work is a "long way" from the front end, so you can imagine my surprise (read: irritation) when upon completion of this extensive restoration work, I found myself with a totally deaf set! +

I've seen tatty RA17s but never a codged RA17, and I've looked over a few. What would be the point? There are outputs for LF adapters and SSB adapters and just about any 'improvement' would be anything but.

Originally Posted by G8DLH

I can only conclude that all that heaving about on the bench must have upset something mechanically - e.g. the trimmer or ??
My provisional re-alignment has resulted in different settings in various places (L's and C's)

The job's far from finished yet. (The calibrator is non-functional ). When it is, I shall make detailed notes (based on measurement) on signal levels at various points for future reference. In the absence of a spare set for bits (oh, joy!), seems the best I can do.

Will report again later - when there's more to tell.

Al /G8DLH

My second RA17 was bought for less than the scrapper because the bloke who owned it had found that the first VFO played up and rather than touch it, had sold it. It was easy to partly sort it out, but I've either got to swap in a 1st VFO from an RA17L or sort the original properly. Your post has inspired me to dust it off and get it working on all the Megacycles ranges, rather than about 6 of them. I'm also starting to regret the 20 or so RA 17s I didn't buy.

Dead RA17s are worth looking out for, but addictive. If another scrapper came up, I'd take it and think about returning the 1st scrapper to use. They also draw you into sweep generators and scopes beyond which most folks need.


Anyway, keep us posted.

Pete.

[Skywave]

Originally Posted by XTC

. . . someone suggested that it was a resonance in one of the die-cast cavities causing the problem, so they cut a slot in the chassis with a band saw and that fixed it" . . . .

They did WHAT? Now, if we are talking microwaves here, I could find this believable, but . . . However, if that's what happened, then that's what happened. Makes you think a bit 'though . . .

Yes - I am aware that there are all sorts of "variants on a common theme" when it comes to CV valves. Take the ubiquitous EF91 for example. Care is required when replacing: it would appear that just slapping in "any old equiv". to a CV4014 (I think that's right) won't do!

"Your post has inspired me to dust it off and get it working . . ." Glad that this thread of mine has produced a (hopefully) beneficial side-result!

"I'm also starting to regret the 20 or so RA 17s I didn't buy." HOW many? Now I can readily believe that the "RA-17 operator / owner thing" is addictive - and, yes, as a piece of innovating engineering in radio technology, it's quite unique and can be a joy to operate - but twenty? And where, exactly, does one house twenty, pray tell? (More to the point, how could I smuggle 20 in past the wife & keep them hidden? Dammit, you've got me thinking about this now! )

Sweep generators, etc. Yes - I know what you mean, but an RA-17 is a serious piece of kit and as such warrants serious kit to keep it going. It's also worth getting acquainted with sweepers etc. for all sorts of other things: TV alignment and any radio with variable IF BW springs to mind - e.g. certain Eddystones. It also takes out most of the guess work - you get "dynamic feedback" whilst you make adjustments. Can save lots of grief.

So there we are. Thanks for the replies - will report again when there is more to tell.

Al / G8DLH

[Skywave]

Originally Posted by G8DLH

Eventually, I hope to use an Anritsu SA with its built-in TG (100Kc to 6.5 Gc)

Update: For those who may wish to know . . . .

Today, at work, I asked "sir" very nicely about this.
"No chance!" came the reply. "They cost a fortune!" (As if I don't know this). "You might break it - then what?"

The fact that I'm using it almost every day on a whole raft of things (uV FM receivers to KW VHF TXs, et al) didn't appear to seem relevant somehow - but I do respect the right of the owner to say "NO!"

Oh, well, have to think of something else . . . . . . . . might help . .

Al / G8DLH

[XTC]

Originally Posted by G8DLH

"Your post has inspired me to dust it off and get it working . . ." Glad that this thread of mine has produced a (hopefully) beneficial side-result!

Fixed it. It was two of the adjustable vanes on the variable cap contacting the static plates ever so slightly. I just tweaked them so there was a hair's breadth gap visible over all the travel and put it back together. Now it works over all the MHz ranges rather than two or three. If the worst had come to the worst, I would have swapped in the other VFO, but it's from an RA17L and the set is a MKII. I don't like tweaking cap vanes, but there didn't seem much option. The MHz dial seems well calibrated all through.

The steel roller in the film scale path was stuck, but that responded to a bit of sewing machine oil. Had to take off the film scale to get at it properly though. Getting the film scale back and properly tensioned is fiddly.

The sensitivity isn't bad, but not what it should be. Time to look at the 37.5MHz and 100KHz IFs. The 40MHz filter will have to wait til I find something which can sweep it.

Pete.

[Skywave]

Originally Posted by XTC

Fixed it. It was two of the adjustable vanes . . . The 40MHz filter will have to wait til I find something which can sweep it.
Pete.

Excellent! Well done!
When you described the fault, I thought "strange - sounds like something mechanical" - I couldn't quite figure out how it would go deaf above a certain Mc/s dial setting . . . . . But now we know!
Mine is now a lot better - almost there! A trimmer in the 37.5 Mc filter was "jumpy". Had fun getting the calibrator to work 'though. Adjustment of the 100Kc and 900Kc LC ccts. is critical if you only want 100Kc and nothing else. The real head-scratcher was when the set was switched to stand-by. On going back to Man or AVC, sometimes result was no cal. + deaf set! (This was NOT the original fault - which was a deaf set permanently). Cause = 1Mc xtal osc. LC cct. slightly off-tune. When coming out of stand-by, the HT rail is slightly less and the osc. sometimes wouldn't start! Hence, no cal. - and no harmonic gen O/P - so no 37.5 Mc. drive!
At the moment, the S/N is not to spec. - I suspect a tired RF amp - E180F.
I was hoping to check the 40 Mc BPF - like you - but I coudn't get my hands on the necessary kit. However, I don't suspect it - it's just a peace of mind issue.
So there we are. Again, my thanks go to you, Jim B. and all the others on this Forum who provided assistance.

Al / G8DLH

[Skywave]

Originally Posted by XTC

. . . I've I'm also starting to regret the 20 or so RA 17s I didn't buy . . .
Pete.

I assume that you aren't trying to say that you had the option of buying "20 or so RA-17s" all at one go!
More to the point, however: where would you KEEP "20 or so" RA-17s ?

Regards - Al / G8DLH

[XTC]

Originally Posted by G8DLH

I assume that you aren't trying to say that you had the option of buying "20 or so RA-17s" all at one go!
More to the point, however: where would you KEEP "20 or so" RA-17s ?

Regards - Al / G8DLH

No not all together, but they're the ones that tempted me slightly from time to time. You can get a Racal rack that holds a few and the associated LF and SSB adapters etc. You'd need a concrete floor. For the right price I'd have another to add to the two and a half I have now..

With a DFM to check the frequency, an RC oscillator looks stable enough to set up the 100KHz IFs. In any case, there are 100KHz quartz crystals and making up something suitable around one shouldn't be hard. I don't have an RF generator that goes down that low, that's any good. The 37.5MHz filter doesn't need swept alignment and a decent RF generator should do. The 40MHz filter is the problem. Lab grade RF generators do FM, but I don't think any do a wide enough deviation at 40MHz. - it's usually about 300KHz

40MHz +/- 1.5 MHz - it might just be possible to make something up. I'm not normally very keen to make test equipment. You can usually buy something ready made that's a lot better, but I haven't yet seen a sweeper that will do the job for anything like reasonable price. For a specialised thing with restricted use, home-brew sometimes makes sense.

Valves go tired, and the bases can respond to contact cleaner. If you don't have a spare E180F you could swap the ones you've got around and see if that makes a difference.

Pete.

[Sean Williams]

Originally Posted by XTC

Lab grade RF generators do FM, but I don't think any do a wide enough deviation at 40MHz. - it's usually about 300KHz

40MHz +/- 1.5 MHz - it might just be possible to make something up. I'm not normally very keen to make test equipment. You can usually buy something ready made that's a lot better, but I haven't yet seen a sweeper that will do the job for anything like reasonable price. For a specialised thing with restricted use, home-brew sometimes makes sense.


Pete.

It might be worth looking out for a HP8640b - it has variable bandwidth fm modulation - I am planning to try this as a swept source - there are a couple on the next tender at www.ramco.co.uk

Worth a go really, especially as the R+S Swob 2 are getting harder to find, and are a pain to store......

Cheers
Sean

[XTC]

Originally Posted by m1ecy

It might be worth looking out for a HP8640b - it has variable bandwidth fm modulation - I am planning to try this as a swept source - there are a couple on the next tender at www.ramco.co.uk

Worth a go really, especially as the R+S Swob 2 are getting harder to find, and are a pain to store......

Cheers
Sean

I've got an 8640A. It's a magical piece of kit. The FM range is 320KHz max on the 30 to 64 range and that's not quite enough to sweep the 40MHz filter. I don't know about the 8640B but I'll check it out. I thought the only real difference was that the B has a digital display and is usually a lot dearer, but thanks for the tip.

There are Wavetek and Wiltron sweepers, which look as if they'd do the job, but the ones I've seen have been a bit pricey. With some of them you have to make sure you have the right plugins and a lot of them are offered with GHz range plugins.

Most of the things I want to sweep are 455KHz anyway, which means either finding something which can do both or getting further plugins.

There's also the HP 8601? It's a good piece of kit, but it's notorious for relying on a couple of unobtainable hybrid circuits, so if you get one that's not well, say from a well-known internet auction site, your chances of fixing it aren't great.

There always seem to be a lot of sweepers on the US ebay site for not too much, but you have the carriage to pay for and probable import duties.

Building a sweeper seems like a ridiculously ambitious project, but putting together something to just sweep 1MHz either side of 40MHz may be approachable.

Thanks for reminding me about ramco. I used to see their ads in WW and they seemed to have some good stuff at reasonable prices from time to time.

Pete.


Pete.

[ppppenguin]

Would a television style wobbulator be good enough for sweeping around 40MHz? Definitely cheap and cheerful compared to decent professional sweepers but ample sweep frequency range.

[Skywave]

Originally Posted by m1ecy

It might be worth looking out for a HP8640b - it has variable bandwidth fm modulation . . .
Sean

Now this is where I get a little confused - perhaps I am giving myself an unnecessary problem.
My understanding of a sweeping SG is one that increments its freq. from, say, F1 to F2, and whilst doing this, will generate a ramp voltage whose magnitude is linearly proportional to the instantaneous freq. between F1 and F2. At the end of the sweep at F2, the freq. will very rapidly "fly back" to F1 and the whole cycle repeat. The generated ramp is used as an external TB input to a CRO.
The significant point is that the forward sweep is "one way", i.e. freq. increasing (or decreasing), followed by a quick "restart". With a freq. modulated SG, where the FM is symmetrical, (e.g. a 8640) this is not obtained - let alone the O/P ramp generation.
Therefore, how can a device like the 8640 meet the need as a swept signal source for filter alignment when used with a CRO ?

Your advice will be appreciated!

Al / G8DLH

[Sean Williams]

The simple answer really is that it will not, but in the absence of the right tool a frequency modulated generator will go some way towards alignment.

I use one here to do domestic IFs - I do have a wobbulator, but it is not compatible with the modern scope......

so, there you go , a crude way around doing IF alignment - no substitute to a proper sweeper, but loads cheaper than getting something proper!

Cheers
Sean

[Skywave]

Originally Posted by m1ecy

. . . . a frequency modulated generator will go some way towards alignment . . . I use one here to do domestic IFs -
so, there you go , a crude way around doing IF alignment . . .
Sean

Thank you. OK, so here we go . . . You can teach me something here, please . . .
So, say I've got a SG that I can freq. modulate, say +/- 25 kc/s (or possibly more) on a base carrier of, say, 465kc/s and a decent 'scope. What is the method of equip. connection & configuration to give a display on the 'scope of the passband of the IF amp. under investigation / adjustment?
I ask this Q. in all sincerity because I know - as you do - that the "sweep method" is a superior way of doing IF alignment. I have receivers that use a range of IF freqs. from 85Kc/s to 1620 kc/s that could benefit from this "crude" method (your words) - as you say, in the absence of a genuine sweeping SG - but, presumably, superior to the "spot freq. and tune everything for max. O/P" approach.

Thanks .

Al / G8DLH