[Heath] Fw: Heathkit SB-610

Thu Mar 8 10:52:06 EST 2012

I may be coming into this notes stream a bit late.....But I've had great success with connecting SB-610's to various Heath transceivers. I use RG-174 coax within the transceiver to the output jack and ordinary RG-58 from the transceiver to the SB-610. I use a 6pf cap to connect the IF board to the RG-174. 

it may sound obvious, but check the wiring of your SB-610 to insure the component values and wiring are for 3395 khz. Also, you have to peak the coils within the SB-610 for max amplitude once connected. You should get a nice full screen image on the CRT if all is working OK. If not, I'd be checking the amplifier stages within the SB-610. 

Interesting to note...if the gain pot on the SB-610 is full up and your on the low end of 80 meters...you'll get a feedback howl in the receiver. I've noticed this on all of my Heath transceivers with an SB-610 connected. When it occurs, you simply reduce the vertical gain pot until it goes away. 

Mark V Johnson VE3LU

From: kf4nsradio at verizon.net
To: rgroh at swbell.net; mdilli at nnwifi.com; ma.locksmith at juno.com
Date: Thu, 8 Mar 2012 10:12:25 -0500
CC: heath at puck.nether.net; heathkit at mailman.qth.net
Subject: Re: [Heath] Fw:  Heathkit SB-610

OK, now the brain is beginning to  
compute correctly.  I do see what you all are saying. I was way off track. 
It does  make sense. Actually Heath recommends a 1uuf cap for the 3395khz 
IF. Sound like if I lower it to 1uuf and replace the RG-174 with some RG-62 
and also use RG-62 from my xcvr to the vert input of the 610, I will gain some 
gain. I will also  remove the mod that lowered the IF gain at the 2nd IF 
with a drop in screen voltage and realign the HW-100. The combination of that 
should give me the higher gain that the 610 calls for at the vert input (min. 
.5v). 

Thanks for all the great responses and 
I appreciate the theory lesson. I just don't have the processing power I used to 
have.

73, Dick KF4NS
St Petersburg, FL 
33714 USA
Keep The Glow!

  ----- Original Message ----- 
  From: 
  Robert Groh 

  To: mdilli at nnwifi.com ; Dick 
  KF4NS ; ma.locksmith at juno.com 
  Cc: Heath puck list ; heathkit at mailman.qth.net 
  Sent: Thursday, March 08, 2012 9:36 
  AM
  Subject: Re: [Heath] Fw: Heathkit 
  SB-610

  Morris has it dead on.   If you think about it this 
  way:

You have a cap (5 pf in your example) connected from the source 
  (the IF Amp plate) to a load (the coax which drives the SB-610 and then the 
  input circuit of the 610 which has some (assumed) input impedance - lets say 
  the 610 input looks like 20K ohms in parallel with 10 pf. 

For all 
  practical purposes, we can say the coax just looks like a shunt capacitor (x 
  ft at y pf/ft).  This coax capacity is in parallel with the 610's 
  input.

So we wind up with our source driving through a 5 pf cap to a 
  parallel RC network - and the easiest way to think of this is that the 
  combination is a voltage divider (yeah, I am simplifying it!).   As 
  an example, assume we have 5 pf in the series capacitor, 15 pf of coax 
  capacity, 10 pf of input C at the 610 and we ignore the R component. We would 
  have a voltage divider of 5 pf working against 25 pf or a 5/30 voltage 
  divider.  

You can readily see that the longer the cable or the 
  higher the coax capacity per ft, the higher the voltage division ratio. You 
  can of course increase the series cap to offset this (e.g. 10 pf --> 10/35 
  ratio) but the trade off is that you are now affecting the tuning of the IF 
  stage more. 

A picture is worth a thousand words but hopefully this 
  will help.

73
Bob Groh, WA2CKY

  From: Morris 
  <mdilli at nnwifi.com>
To: 
  Dick KF4NS <kf4nsradio at verizon.net>; ma.locksmith at juno.com
Cc: Heath puck list 
  <heath at puck.nether.net>; heathkit at mailman.qth.net
Sent: Wed, March 7, 2012 6:25:29 
  PM
Subject: Re: [Heath] Fw: 
  Heathkit SB-610

I may be wrong but I've always expected the 
  capacitance of coax to be
expressed from shield to center conductor, not 
  serially.  In this case you
would not have a simple series connection 
  of two capacitors and the
equipment in question.

Morris 

> -----Original Message-----
> From: heath-bounces at puck.nether.net 

> [mailto:heath-bounces at puck.nether.net] 
  On Behalf Of Dick KF4NS
> Sent: Wednesday, March 07, 2012 2:43 
  PM
> To: ma.locksmith at juno.com
> Cc: 
  Heath puck list; heathkit at mailman.qth.net
> 
  Subject: [Heath] Fw: Heathkit SB-610
> 
> 
> Ok guys, most 
  responses have been related to the coax. Since 
> there is no loss in 
  the 610 and the vert amp 
> is doing its job the loss is obviously in 
  the originating 
> equipment. Also, Heath does not say you should 

> use RG-62, it only mentions the best coax for the xmit 
> 
  input/output. There they say to use 50 or 75 ohm 
> coax.
> 

> I was doing some thinking (bad for someone my age) and 
> 
  remembering electronics school, as I recall 
> capacitors in series are 
  equal to a value lower than the 
> lowest capacitance. (smaller than the 
  smallest 
> as I remember) so my 5uuf cap in series with the 93ohm coax 

> should result in total capacitance less than 
> the 5uuf cap in 
  series.
> 
> Hmmmm! Is my age showing or am I thinking correctly. 
  Some 
> have said they use all different types of coax 
> with no 
  trouble. What if I used just a piece of insulated 
> wire from the 2nd 
  IF to the jack on the xcvr 
> back and use coax from there to the 610 
  ?
> 
> 73, Dick KF4NS
> St Petersburg, FL 33714 USA
> 
  Keep The Glow!
> 
> 
> ----- Original Message ----- 
> 
  From: <ma.locksmith at juno.com>
> 
  To: <kf4nsradio at verizon.net>
> 
  Sent: Tuesday, March 06, 2012 6:52 PM
> Subject: Re: [Heath] Heathkit 
  SB-610
> 
> 
> | Yes, the coax IS faulty....  but, not 
  because it's broken
> |
> | You have selected wiring with very 
  high capacitance.  This makes a 
> | capacitive divider for the 
  signal.  If you only have 5 pF 
> capacitance 
> | in the 
  cable, you have a 2:1 reduction in signal strength.
> |
> | RG174 
  and RG58 have high values.  I think the 58 is 32 pF 
> per 
  foot.  
> | Not sure about the 174 unless I look it up.
> 
  |
> | I expect the "right" cable between the set and the 610 will 

> be RG 62. 
> | And, more than likely, unshielded wire 
  inside.
> |
> | Ed
> | K1ZOK
> |
> | On Tue, 06 
  Mar 2012 15:58:50 -0500 "Dick KF4NS" 
> | <kf4nsradio at verizon.net>
> 
  | writes:
> | > Looking for your input and recollection of what you 
  did. 
> I have now 
> | > completed a full restoration of my 
  SB-610 and have concluded that 
> | > the one remaining fault, low 
  vertical gain, may  be due to how I 
> | > have connected it to 
  my HW100.
> | >
> | > It did work pretty good at one time so 
  now there is a bit of head 
> | > scratching. I  have no losses 
  in the 610 and the vertical 
> amp, when 
> | > driven with a 
  sig gen at 3395khz modulated at 50%, I see 
> .4v (spec.
> | > 
  recommends .5v input) at the grid and get 23v at the plate. That
> | 
  > sounds like the 610 is doing the job.
> | > The vertical gain 
  pot is fine. So now I suspect it has to be the
> | > connection to 
  the rig.
> | >
> | > I used RG-174 in the HW100 from the 
  second IF plate and 
> have a 5uuf 
> | > cap in between. 
  Outside the rig I have a short run of 
> RG-58 to the 
> | > 
  610. I can only see .1v from the rig. The coax is not 
> faulty nor is 

> | > the capacitor.
> | >
> | > What did you use 
  in your Heathkit rig for coax and 
> coupling cap. and 
> | > 
  what did you feed the 610 with? Did you connect to the first or 
> | 
  > second IF and at the control grid or the plate? I did do a mod to 

> | > the 100 which lowers the IF gain to improve gain 
> 
  distribution. This 
> | > came from my friend Mark's (WB8JKR now 
  SK)
> | > presentation for optimizing the HW/SB transceivers. When 
  the scope
> | > was working fairly good this mod was
> | > 
  already there. I did realign the rig though at some point since
> | > 
  then. The 100 is working great.
> | >
> | > Thanks and 73, 
  Dick KF4NS
> | > St Petersburg, FL 33714 USA
> | > Keep The 
  Glow!
> | >
> | > 
  _______________________________________________
> | > Heath mailing 
  list
> | > Heath at puck.nether.net 
> https://puck.nether.net/mailman/listinfo/heath
> | 
  >
> |
> | 
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