SB-610 coils

[charles w. morehouse]

Hi Gerry,
Just restored an SB-610 to original as it had been butcherized. Wired it
for 3395 IF. Found some new parts to bring it back to stock so have some
extras as follows:
2ea 40-746 coils
1ea 40-747 coil
1ea 84-39 phase network
1ea 84-40  "       "
1ea 63-138 attn sw
1ea 63-77 3 pos sw
Restoring an HO-13 to use with my R-390A so I need the coils for 455kc.
1ea 40-588 osc coil
1ea 40-590 350kc trap.
Would be glad to sell or trade the new parts for the ones needed. Happy
holidays to all, 73.
Wayne;
W4GBW

wa1vwl wrote:
>
> I measured the inductance of the SB-610 vertical amplifier coils today. I
> also dug up the manual to refresh my memory. The parts list in the manual
> shows there are 3 coil selections in the plate and 1 at the grid. I didn't
> have grid coil handy. It's used for 3 - MHz only. I've never used my SB-610
> with Heathkit SB/HW receivers because it is of limited value to monitor
> received signals with those rigs. The IF bandwidth is too narrow to show
> what's really going on with the other fellow's signal. It is nice to see,
> however. Especially when you have visitors in the shack. The equipment used
> to measure inductance was an L/C Meter IIB, a product of Almost All Digital
> Electronics. I checked its accuracy against the lab standard at work and
> like they say, it's amazingly accurate with low inductance and capacitance
> values.
>
> 40-746 Low frequency coil, 455 - 2475 KHz, nom: 534 uH  min: 250 uH  max:
> 580 uH
>
> 40-747 Medium freq coil, range: ? , nom: 47 uH,  min: 42 uH,  max 206 uH
>
> 40-748 High freq coil, 3 - 6 MHz, nom: 23 uH,  min: 12 uH,  max: 29 uH
>
> The nom(inal) value is what the coil initially measured. Min was with the
> slug almost all the way out and max with the slug adjusted to read the
> maximum
> value.
>
> For use with my Drake R-4B, a 50 KHz IF, I used a parallel resonant circuit
> at the plate of V2. It consists of a 44 mH toroid, 150 pF cap, a 5 - 60 pF
> trimmer and a 100 KOhm resistor across the combination to kill the Q. The
> circuit is too sharp without it and gives false indications. With this
> circuit, the vertical gain is around 3 o'clock. I coupled to the last IF
> stage with a simple FET follower near the IF transformer so I didn't have to
> worry about the length/type of coax used or wether there was any coax
> connected at all. When everything was hooked up, I simply adjusted the
> trimmer cap for maximum response on the CRT. The circuit is built on a small
> piece of perf board attached to the chassis with a bracket taken off a
> terminal strip.
>
> As for monitoring 455 KHz signals, I wonder if anyone has ever tried a
> standard 455 KHz IF transformer. I don't see why it wouldn't work. If memory
> serves me right, they're around 1 mH. So what if the impedance is high, all
> we're trying to do is look at voltage. If oscillations occured, I would try
> the same thing I did with the 50 KHz circuit: resistance across the coil to
> dampen the Q. For other frequencies, I'd try winding a toroid and use a
> trimmer cap. It's worth a shot. Waiting to find those missing SB-610 coils
> might take a very long time (if ever) and involve a certain amount of good
> luck.
>
> 73/Gerry/W1ID
>
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